Atari 800 Operating System Manual, Part 3 Of 4

INO INTERRUPTPROCESS

6

Section 6 d€sciibeg 6{steo Ections foi the vatious interrupt c e u g i n g o v e n t E , d e f i n e s t h c n a n g R A I i Iv € c t o r E a n d p r o v i d e E r.ecoonendad procedur.es for de€ling uith intet'rupt9. The 69Oa microcomputer proEes6a6 three g€n€raI inter.iupt tgpeE: (Nl'lI, and mEEteble i'1te.rupts Ehir-reeet, nonn€st€bIe interrupts (IRO'. The IRG inteirupt tgp€ can be enebled and disabled using The Nl'lI tgPe .ennot be the 6502 CLI end gEI inrti.u€tiotr5. diEabted at the oroces6or leveL but the NltI interruptE other t h a n I S Y S T E HR . ESETI keg can be disabled at the ANTIC chip. The sqstem €v€nts thet ch ip-reset

-

cen cauEe interrupts

are list€d

po { r e r _ u p

(!nuEed bq OSI Nl'tI - Dirpleg li6t interr'!pt ( 5 0 1 6 0 Hrl ver.tiee I-b lant [SYSTEI'{. RESETI keg IRO - 56fi.I buF output reEdg sar ia I buE output coftptete S e ai a 1 b u s i n 9 ! t " e a d g Serial bus pro€eed lina (unused bg Eg6ten) SeFiil bus inter.upt line (unu6ed bg 5q6teo) POKEY timer's 1, 2 and 4 Kegboard ketJ IBREAKI *eg (unused bg OS) 65Oa 8RK inEttuction Figut'e 6-l

List

of Sqste -Interrupt

Events

OPERATINGSYSTEI'ICO16559 -102

SeEtion

6

belot:

T h e c h i p - r e s e t i n t e r r u p t i . s v e c t o r € d v i s l D c s t i o n F F F C t d E 4 7 7' u h e l . e e J l v l Pv e c t o r t o t h e p o u e r - u p r . o u t i n € i s 1 o . : t e d . All NHI intertuptE a.e vectored via locatioh FFFA to the Nl,lI inteitupt servite routine et E784, a'ld €11 IRQ interrupts are vectoied via location FFFE to the IRC i.nterruot seivice routine at E6F3, at that point the casse of the interrupt nuEt be determined bV € serieE of teEts. For sone ot the events there ere built in dronitor actions and for other eventE the ro.responding inte?rupts 3re di6abled or ignored. The Egstsm provides RAM vectot6 so that gou can intercept interfupts uhen nec€59€rg.

The OS genei'ateE chip-reset in responsE to e pouer-up condition. (see Section 7). The s{Eteo i5 coop!etelg initialized

NONITIASKASLEINTERRUPTS Whenan NMI intenrupt occuts, control. iE tranEferred thr.ouqh t h e R O Mv e c t o r d i r e r t l { to the sggternNHI interrupt Eervice routine. A ceuEe for the interrupt i5 deterlnined bq era$ining h B r d q , e r e r € g i E t e r N f , l I S T t D 4 O F l . T h e N l 4 I n a k e s E J U r n pt h r o u g h t h e 9 l o b a l R A | 1v e c t o . V D S L S T t O e O O l i f a d i E p l a g ! i E t i n t e r r . u p t i s pending. The OS doeE not !Fe displaq list interrupts, Eo VDSLST i5 initi.atized to point to an RTI in6truction, End gou rnost not € h a n g e i t b e f o r e V D S L S Tg e n e r a t e s a d i 6 p l a g i n t e r r u p t . I+ the interrupt is not a displag-li6t interrupt, then e ts6t ig f t e d e t o 6 e e i + i t i E e I S Y S T E MR . ESETI kerJ interrupt. If so, then a i s m a d e t o t h e E V E t e m r . e s e t i n i t i a l i z E t i o n r o u t i n e (see Section JUmp 7 f o i d e t a i l s o f s g s t e m r s s e t i n i t i a I i r e t i on ) . I+ ths interr.upt is neither' e dirpteg list interr.upt nor E [ s Y S T E M .R E S E T ] k e g i n t e r r u p t ; th€n it is asEUmedto be e ( V B L A N K }i . n t e r r u p t , a n d t h e + o l l o u i n g a c t i o n g verti{e1-blank o c c tl : RegiEterE A,X end Y are puEhed to the stecft. The interrupt

request

i.s cleared

( N l ' I I R E St D 4 O F l ) .

global A Jlop iE tnadethrough the "immediate" v€itic€1-blan* R A I ' Iv e c t o r V V B L K I f 0 2 2 2 1 t h a t n o r m a l l U p o i n t E . t o the Stag€ 1 V E L A N Kp . o r e r s o r . The +ollouing

action6

occur:rEgu.|ling that

gou have not chEnged VVBLKI.

OPERATINGSYSTE|1CO16559 -*

Se€tion

6 103

T h e E t a g e 1 V B L A N Kp r o c e s E o r i i

exacuted.

The OS teits to 5ee i+ a rFitiE8l code g€Etion has been inteiruptad, If Eo, then alI regieteis €r6 restored? end en RTI ingtr.uetion ieturn6 from the interruot to the aritical sectiofl. A c!.itical sertion ii determined bV examining ihe CRITIC +1ag [OO42], €nd th€ procesEol. I bit. If either are $et, then the interrupted Fection ii asEUoedto be aritical. I + t h e i n t e r r u p t u r a En o t f r o n a c r i t i c a l 6 t a g e 2 V B L A N Kp r o c e E s o r i s e r e c u t e d .

6ection,

then the

The OS then Jumpi thtouqh the r'detcried" vertical-blanl global RAH vactor VBLKD t0224l, that nor'onllq points to the V B L A N Ke r i t r o u t i n € . The +ollouing

aations

ocrui

a6g!oing th€t

o

The 650A A,X €nd Y r.egist€iE

o

An RTI instiuction

gou have not ch€nged VVBLKD.

ara r'estor.ed.

is ereauted.

NOTE: You c.n alter the defer!'ed and ifioediate V B L A N KR A M v a a t o r E , b u t s t i l l eneble nornal Erjiiteo proae6ies, or restore original vectors !rithout having to save thern. The instruEtion et E45F is a Ji'lP to the stage 1 V8LANKpro€esEori the addresE at EE46O,21 is the velue norlrlellg +ound in VVBLKI. The inEtruttion a t E 4 6 2 i s e J l ' l P t o t h e V S L A N Ke x i t ? o u t i n e ; the address at tE463,21 iE the value t|or.mdllg found in WBLKD. TheBE R B M v € c t o r s t o s t a g e l V B L A N Kp r o r e i s o r e n d t o t h e V B L A N Ks x i t ioutine uill accompli5h gour go{tl. NOTE: Everq VBLANKinterrupt Jui[pE through vector vvELKL OnIq V 8 L A N Ki n t e r r u p t s f r o o n o n c r i . t i c a l c o d e s e c t i o n s J u n p t h r o u g h vector VVBLKD.

Stag€

1 VBLANK Proc eEs

The +olIot ing stag€ 1VBLANK proce6Eing iE perforned at everg VBLANKin teF.up t: T h a s t a g E l V B L A N Kp r o c e e s i n c r e m e n t s t h a 3 - b g t e f r a | | l e countei RTCLBK !OO12-OO14J, RTCLOK+O is the l4SB and RTCLOK+2 i 5 t h e L S B . T h i E c o u n t e i u r a p E t o z e r o & r h e ni t o v e r + l o u 5 ( e v e r q 7 7 h o u r " Eo r . s o ) , a n d c o n t i n u e 6 c o u n t i n q . The Attr'€Et mode v€riebleE are pr.t6es6ed (Eee Appendix L, 410- le ' . T h a s t a g € l V B L A N Kp r o r e g s d e c r e r n s n t s t h e S g s t e n T i f t e r 1 CDTtM tO218,21 if it i6 nonzero; if the ti|ne. ooes fiom O P E R A T I N GS Y S T E I ' C I O16555 -104

Se€tion

6

n o n z e i o t o z e r o t h e n a n ind ireE t

JSR iE

perforned

via

CDTl.tAl

S t a g e 2 V B L A N KP r o c e E s T h e s t a g e 2 V E L A N Kp r o r € E s i n g p e r f o ? m s t h e f o l l o u i n g f o ? t h o s e V B L A N Ki n t e r l ' u p t s t h a t d o n o t i n t e r r u p t c r i t i c a l sectionE: T h e s t € g e 2 V B L A N Kp r . o c e s s € I e E r s ThiE enables the IRG inter.urte.

the 6502 processor

I bit.

T h e s t e g e 2 V B L A N Kp ? o c e s 6 u p d a t e s v a r i o u 6 h e f d u a f e r e g i s t e r E u i t h d e t € + r o n t h e O S d e t a b E g e , a s s h o u j nb e l o u : D a t e B EE e I ten

Hat durare Register

R e es o n f o r

5DL5TH SDLSTL SDtlCTL CHSAS CHACT OPRIOR

DL ISTH t D4031 DL ISTL t D4021 Df'IACTL tD400J CHBASE tD409l CHACTL cD401l PR I T]R cD o1 s : COLPFO t D o 1 6 1 COLPFl c D o 1 7 l COLPFA t D o 1 8 l COLPF3 t D o1 9 l COLEK t D o l A l

D i s pl a g I i E t

to231 l t0230l EO22F 1 EOZF41 to2F3l

coLoRot o2c4l coLoR1 t ozc5l

CALBRE t o z c 6 l

coLoRS toecTl coLoR4 t02cBl PCOLRO t ozcol PCOLRl t o 2 c1 l PCALR2 t o z c 2 l PCOLR3 to2c3l Constant = B

U pd a t e 6t:rt

A t t i a c t m o de .

c oLPr'10EDOl2l c oLPt'rI ( D O1 3 l Ct]LPM2 t D o 1 4 l coLPi,{3 t o o 1 5 l

C o N S A Lt D O t F l

C o n s o1 e s o e a k e r o f + .

T h e s t € g e 2 V B L A N Kp r o c e 6 s d e E r e m e n t 5 t h e S g E t e m T i m e r 2 C D T H V zt 0 2 1 A , 2 l i f i t i s n o n z e i o r i f t h e t i m e i g o e s f r o m nonzero to zero, then an indiref,t JSR i5 oerfor|ned throug h CnTHA2 tO22E'27. T h e s t a g e 2 V B L A M Kp r o c e E g d e c r e o e n t s g u g t e m T i o e r s 3 , 4 a n d 5 i+ theg are non!ero; the corresponding +lag5 ai. ret to zero for each timer th€t chanoeE fron nonzero to ,e?o.

B P E R A T I N GS Y S T E | IC O 1 6 5 5 5 - -

Section

6 105

T i r n e r T i m e r V E1 u e 3 4 5

C D T H V 3t O 2 1 C , 2 l CDTHV480 21E,21 CDT}4VSt02eo,2l

Tifter

F 1a9

C D T M F 3C O 2 2 Ar,l CDTMF4tO22C, I l CDTMFStoeeE, 1l

A c h a r a c t e r . i s r e a d f r o n t h e P O K E Yl e { b o r r d F e g i 6 t e r Etor'ed in CH IOAFCl, if €uto reDE:t iE sctive.

and

T h e 6 t E g e 2 V B L A N Kp r o r e E E d e c r e f i e n t s t h e & e g b o d r d d e b o u n c e counte? if it i€ not equal to zero, end if no te{ iE T h e E t e g e 2 V B L A N Kp r o c e s s p i o c e s r e s t h e & e V b o a r d a u t o r e p e a t ( s e e A p p e n d i xL , E B ) . T h e s t e g e 2 V A L A N Kp | . o E e g s r e : r d 6 g € l n e c o n t r o t l e r data fionr the ha.d0rdre to the FAM date b€se, as shourn belo!r: HatduEre R € gi 6 t e r

D€ta BaEe I tem

PORTA tD3OOI

S T I C K Ot o z 7 A l JoUEtirtE and STICK1 to279l PTRIeOIO27C] Paddle Controller.s PTRICl IO27D] PTRIC2 IO27E] PTRIO3 [O27F1 STICKz tO27Al STICK3 CO27B l PTRIC4 IO2BO] P T R I G ST O 2 A 1 1 P T R 1 0 6T O 2 B 2 ] PTRIOT [0243] P A D D L O[ O 2 7 O ] P a d d l e C o n t r . o I l € r . E P A D D L 1r 0 2 7 1 l P A0DLa CQ2727 PADDL3 t0273l PADDL4 to274l PADDLSIO279] PADDL6 to276l PADDLT 84277 7 S T R I e OI O p a 4 l JogEtick triggerE. STRIGl t0295l STRIGz to2a61 STRTC3 toe87l

PORTB tD30t I

POTO POT 1 POT 2 POT 3 PoT 4 POT 5 POT 6 POT 7 TRfGO TRIOl TRIO2 TRIG3

tDzOOl tD201: tD202l tD203l tD204t TD2OsI tD206t TD2O7] CDOOIl rDOOat tDOO3l tDOO4l

F u n ct i o n

OPERATINGSYSTEH CO1655S -106

Section

6

MASKABLEINTERRUPTS A n I R C i n t e r ' r . u p t . a u E e E c o n t r o l to be tr€n6ferred th!'ough the i m n e d i a t e I R O g l o b a I R A I ' Iv e c t o i V I H I R O t c 2 1 6 l . O r d i n e i i l q t h i s v e c t o r p o i n t E t o t h e s t l e t e f t I R { l H a n dI e r . T h e H a n d l e r p e r + o r m s th e6e fo I I ouing actions: The IRG Handler determines a aause for the intertugt b{ eramining the IROSI €DzOEl register and the PIA statuE r€giEteri PACTL ID3O2] and PBCTL tO3O3l. The interrupt stetus bit is clear€d uhen it is found. One interruDt event i5 cleared and proaers€d for each interrupt-6ervice entrg. If fiuItipl€ IRCE ere pending, then a gepa.ate inter'.upt uill be generated for 6ach pending IRO, until aII at'e 6e!'viced. The sgEteo IRO interrupt service routine de:ls uith each of the po6sible IRC cauEinq event5, in the follouing uagB: The 6502 A register

i6 pushed to the etac&.

lf the intel.r.upt is d!e then clear the inteirupt veE tor VSEROR IO2OCL

to sst'ia1 I / O b u s o u t p u t r e a d ! , end JUdlpthrough global RAI'I

I+ the interrupt iE due to Eerial I/B buE input readq, t h e n c l e a r t h e i n t e r r u p t e n d J U m pt h r o u g h g l o b € 1 R A H v e { t o r V S E R T Nt o z o A l . I+ the interr.upt is du6 to EeriaI EoflpIete, then Elear' the interrlpt o l o b a l R A l , tv e c t o r V S E R O Cl O 2 O E l .

I/0 bus orrtput t s n d J U r n pt h r o u g h

If the interiupt i s d u e t o P O K E Yt i { t l e r { t 1 , t h e n c l e e r t h e interrupt E n d J U r n pt h r o u g h 9 1 o b a l R A I ' Iv e c t o t V T I I ' l R 1 t 0 2 1 O l . I f t h e i n t e r r u D t i s d u e t o P O K E Yt i n e r * a , t h e n c l e a r t h e interiupt and Jldrp through global RAMveEtol' VTIMRa t0212l. I f t h e i n t e r r u p t i E d u e t o P O K E Yt i m e r * 4 , t h e n c l e 5 r t h e interrupt. The service routine conteins a bug, aod +€lIs inio the +ollouring test. (other If presEing a keqb06rd keg caused the inteirupt than tBREAKI, ISTARTI, IAPTIUNl, or ISELECTI)t then cle€r the interrupt a n d J U m p t h r o u g h g l o b a l R A M v e E t o r V K E Y B Dt O 2 O E l . then I+ pre6Eing the IBREAK] ke! caused the interrupt, S e t t h e B R E A K+ l a g B R K K E Yf O O l 1 l t o clegi the inteirupt. rero, proceed to clear the follouing: Star t/stop flag SSFLAo CO2FFI C u r s o r i n h i b i t f l a g C R S I N Ht O 2 F O l Attra.t m o d e f l e g A T R A C Tt O O 4 D l O P E R A T I N eS Y S T E MC O 1 6 5 5 5 - -

Section

6 107

Return +roo the interrupt re9 ister +roin the Etack.

aftel'

r.estoiing the 690A A

o

I+ the interropt iE due to the sel.ial I/0 bus proceed linei then clear the interrupt, €Dd J!,np through globaI RAHvector VPRCED tO202L

o

If the interrupt is du€ to the ssiiel I/O bus interrupt l i n e , t h e n c l e a r t h € i n t e r r u p t a n d J U m pt h r o u g h g l o b e l R A M vector VINTER CO2O4l.

o

If the inter.upt iE due to a 6502 ARK instFu.tion, t h r o u g h g l o b a l R A M v e c t o r V B R E A Kt O 2 O 6 l .

o

If none of the ebove, iegtore (RTI}. f r{ro the inteir!pt

then Jlnp

the 6503 A "eqigter. and aeturn

I N T E R R U P TI N I T I A L I Z A T I O N T h e i t l t e r r . u p t s u b s g s t e d rc o o p l e t e l q r . e i n i t i e l i z e s itsel+ uhenever t h e e q s t e m i 6 p o u e r e d u p o r t h e I g Y S T E MF . ESETI kerJ iE pres6ed. The BS cleer6 the harduare negiEters, and sets the interr.upt g l o b a l R A t ' lv e c t o r s t o t h e + o l l o u i n g c 6 n f i g u r a t l o n s : Vector

Tlpe

Function

VDSLSTfO2OOl VVBLKI toze2l CDTHAI f0226l C D T M A 2f o ? z A l VVbLKD tG?241

NMI .r " ,, "

RTI -- ignore interiupt. Sgsteo stage 1 VgLANh. 5IO timedut tiftlFr.. No 6usten +unction. S ' fs t e m r e t u r n f r o m r n t e r r u p t .

VIMIRO to216l

IRC

SrrBted IRG processor.

vsERoRtozocl

,,

VSERIN TO2OA]

"

V T I M R 1l o 2 l o l V T l t 4 R 2t o 2 1 2 l VTlt'lR4 to214l V I { E V B Dt O z O A l

" n { ,,

V P R C E Dt O 2 O 2 l V I N T E Rf O 2 O 4 1

,, "

V B R E A Kt O 2 O 6 l

8RK

vsERactozoEl

Figure 6-e

,,

s Io. 5IO.

s Io.

PLA,RTI -- ignore PLA,RTI -- igno?e +.F.FdoeEnrt mEtter Sgsten keqboerd i n t e r r u p t h e n d1 € r . PLA,RTI -- ignore PLA,RTI -- ignoie PLA,RTI --

int€rrupt. interr.upt.

ignore interropt.

I n t e r f o p t R A t ,V l ector Initi€liration

OPERATINOSYSTEI'ICO1655$ -104

interFupt. inter.!.upt. ***

Section

6

Sg6tem initiel as fo I Io{rE:

ization

sets the interrupt

ensble Etatus

NMI

V B L A N Ke n € b l e d , d i 6 p l a U l i i t

IRO

IBREAKIteg and data teg ioterrupte di6abled.

di6ab1€d. enabled, a1l

others

9YSTEH T IIIERS Th€ OS contains +ive gen€r'aI purpose softua"e timers, plus an OS-supported +reme .ounter. The tifters are a bgtes in length ( 1 o , h i ) a n d t h e + r . a { r | et o u n t e r R T C L O Kt O O 1 2 l i 6 t h r e e bqteE in length (hi.,nid,lo). Th€ tifter6 count dounuerd from enV nonzero velue to zero. Up6n ieechiflg zero, theg either clear. an eE6ocieted f1eg, or JSR through e RAll vectoi. The freme counter €ount5 up{rerd, {,rapping to aero uhen it overflous. The follolring t€b1e Ehorrs the tiflers c h e r € ct e r i s t i eE :

Tinei.

Nalne

cDTf,lV 1 tOz 1Bl C D T H V 2t O ? t A I CDIHV3 f O?1Cl cDTr.tv4t oelEl CDTHVSt0e20l RTCLOKtOO1"1

FIag/Veator

and the f!.a|ne counter.

Use

C D T M A 1t o a 2 6 l 2 - b g t e v e c t o r - - S I 0 t i n e o u t . C D T M A at o e ? 8 : 2 - b q t e CDTI.1F3[O22A] 1-bste f l a g CDTI'iF4 tOe2Cl 1-bgte f 1 e g C D T H F St O ? z E l 1 - b q t € f l € g 3 - b gt e f f € m e c o u n t e , ,

These tuo tiners aie maintained ac part o+ ever! VBLANK (Et€ge 1 process'. The other timers ere subJect to inte.rupt the cr.itic€1 section test (sta9e-2 proceis), th€t can defer t h e i r u p d € t i n g t o a l a t e r V B L A N Ki n t e r i u e t .

USACE NOTES This subsection d€6cribes the techniqtres gou need to *nou in order to utilire interrupts in ronJunction trith the operating 5!6ten.

O P E R A T I N GS Y S I E H C O 1 6 5 5 9 - -

Section

6 109

P O K E Y I n t e r r u p t M a sk ANTIC (diEp16'r-li6t and vertiEal-blenl) and PIA (interr.upt a.d proceed lines) interr'upts cEn be fnesled dir€ctIV (see the Haid{rare Hanual }. Ho{rrevei, eight biti of a 6ingle bqte IRGEN (IBREAKI keg, dat€ keg, tDzOEl oast the PO(EY interruptG 9€ti31 input re€dq, seri€I output reedg, serial output done and tinerg 1,2 €nd 4). IROEN is a url^ite-onlV register'. ThuE, llre nu6t naintain a current v€lue of that regiEter in RAMin order to update individuel m€st bitg selectivelg, urhlle not changing other bitE. Ths name of the vaiiable u s e d i e P O K M S K! O O 1 O 1 , a n d i t i s u e e d es shouin in the era|nples belour:

; EXAMPLEOF INTERRUPTENAELE SEI LDA ORA STA STA

t T O A V O I D C O N F L I C T[ , I T H I R A . . . PROCESSORWHICH ALTERS vAR. PIIKMSK , ... *trx ; E N A B L EB f T ( s ) . POKI.{SK IROEN REG TOA. , TO HARDWARE

, EXAHPLE T]F INTERRUPTDISAELE SEL LDA AND STA STA Figuie

6-3

T O A V O I D C U N F L I C Tt r I T H I R G . . . POKHSK ; . . . PROCESSORWHICH ALTERS VAR. { + $ F F - rx ; D I S A B L E B I T ( S ) . PT]KI'ISK IROEN , TO HARDWARE REOISTER TOU.

POKEYInterrupt

MaEk Exanple

N o t e t h a t t h e O S I R O s e ? v i r e r o u t i n e u s e e a n d a l t e r s P O I ( | ' I S K s, o Elt€iations to the variable ou6t be done u,ith interruptg inhibited. If done et the interropt level there is no problem, as the I bit iE elreadg set; if done at a baclground level then the SEI end CLI i.nBtruction€ should b€ u6ed as, shoun in the exallrD1eE.

Setting

Interrupt

and Timer Vector6

g e c E U s ev e r t i c a l - b l a n k inte"r.!pts are gener.allg kept enabled so that t h e f r a m e c o u n t e ! . R T C L O Ki E o a i . n t a i n e d a c c u r a t e l ! , there is e probleo uith setting t h e V B L A N Kv e c t o i e ( W S L K I a n d W B L K D ) o r the tioei v E l u e s ( C D T M V I t h r o u g h C D T M V S )d i r e c t l r J . A VBLANK inteaiupt Eould occur uhen onlg one bgte of the tuo-bgte value had b e e n u p i l a t e d , l e € d i n 9 t o u n d e s i r € d c o n s e q u e n c e E .F o F t h i s r e E 6 o n , O P E R A T I N eS Y S T E MC O 1 6 5 5 5 - 110

Section

6

the SETVBVtE4$Fl rootine i6 Frovided to perfoifi the desired update in gafe mdnner. The cslling gequence is shoun belo{r: A = update ite indicgtor 1 - S f o i t i n e t € 1 - 5 . 6 f o r i f i m e d i a t e V B L A N Kv E E t o r W B L K I . 7 f o r d e f e i r e d V B L A N Kv e e t o i v v B L K D . X = I'ISBof value to store. Y = LSB of value to etore. JSR

SETVBV

The A, X and Y regi5ter.6 can be sltered. The diEpleg IiEt interrupt rrilt eluarJ6 be disabled on return, even if enabled upon entrtJ. It iE possible to full'l process a vertic€l-blank dur ing a aal l to this routine.

interrupE

lrhen uorting uith the SVstem Timer6, the vectorg for tifteis l end 2 end the flag6 for tirrere 3,4 and 5 slrould be 6et uhile the associated ti&er is equal to rero, thsn the tiner should be Eet *o its (nonzer.o) ve1ue.

\_

Stack Content at The +ollooing RAll interrupt

Inter!.lpt

VeEtor pointE

t a b l e s h o u , 6t h e s t a c k c o n t e n t a t vec tor. points:

OPERATINGSYSTEiI COt6555 --

ever.{ one of the

Section

6 111

RAII STACK CONTENT INTERRUPT VECTOR

DESCNIPT ION

OS RETURNCONTROL

VDSLSTlO2OOl WBLKI tO222, * C D T I ' | A !t o 2 2 6 l C D T I { A at o 2 2 g l VVBLKDtC2241 *

Displa'J list V E L A N Ki m f l e d i a t € Sqstem Tifter I Sgstem Timer 2 V B L A N Kd e f e r .

return, return, return, r€turo, retur.n.

P P, P, P, P,

A, A, A, A,

VII{IRO 10216I * V S E R O R[ O 2 O CI * VSERIN [O2OA] * V S E R O Cl O e O E l * VTItlRl toalol VTIMR2 to2lel VTII'iR4 [Oe14, V K E V B Dt o 2 o E l * V P R S E Dt o 2 o z l VINTER tO2O4l V B R E A KE O 2 O 6 I

IRC imnediate Serial out read{ Setial in readq Seri€l out colnpare P O K E Yt i m e r 1 P O K E Yt i n e r 2 P O K E Yt i n e . 4 Keqboard data Serial paoceed Serial int€.ruot gRK initruEtion

?eturn, retur.n, return, return, return, return, return, ieturn, r€turn, ietuin, return,

P, P, P, P, P, P, P, P, P, P. P,

A A A A A A A A A A A

Figure *

6_4

Interrupt

and Timer vector

X, X, X, X.

Y Y, ieturn Yr return Y

RAMStEEt Cont€nt Table

The OS initialires t h e B e e n t r . i e s a t p o u r e r ' - { . r pI .o p r o p e r l g ch6nging these vecto?i uill aIte. sgstem perforoanae.

M i s € e 1l a n e o u s C o n i i d e r € t i o n E The +ollouring paragraphs list conside?ations for the urlter RestrictionE

6 set of igcelleneous o+ an interroot EerviEe routine.

on CIeBring

Displag IiEt. iflmediate vertical-b1Enk and Sgstem Timer {fl ioutines Ehould not cleer the 650A I bit- If the NMI le€ding to one of the6e roLitineg occurred uhile an IRO rres being processed, uith then cle€ring the I bit !rill ca!ee the IRO to re-interrupt a n u n k n o L J nr e s u l t , T h e g S V B L A N Kp r o c e E e 6 r c a r e f u l l ! 6heckE this condition Etage 1 proce5s end before the gtage 2 proceEE,

efte!'

the

I n t e r " t u pt P r o c e E s T i m e R e g t r i c t i o n s You Bhould not ur.ite en inter?uDt routine thet exceedE 4Oo m6ec. u h e n a d d e d t o t h e 6 t a q e 1 V B L A N I , (i,f t h € s e . i a l I/O ie being u6ed. The SI0 6ets the CRITIC flao uhile seriel bu€ I/O is in Prog?e95. O P E R A T I N cS Y S T E I ' C i U16555 --

Sectidn

6

InterruFt

Dela!

Dus to "t"rAIT FUR SYNC"

[,lhen€ver E teg i.s read +rom the tegboer.d, the Keqboard Handler sets l^lsYNC ID4CA] repetstedlg uhile generating the audible rlic* on the EonEole gpeak€r. A ptoblem occurE lrhen interrupts are gen€rated during the u€it-for-EgnE period; the processing of such interruptE rriII be del:qed bV one horizontal scan line. IhiG condition cannot be prevented. You can uor* ar.ound the condition b g e t a n i n i n g t h e I i n e c o u n t V C O U N TC D 4 O D Ia n d d e l a g i n g i n t e r l . u p t p r o c e s 6 i n g b g o n e I i n e { r h e n n o t l S y N Cd e l a g h e s o c E U r r e d .

FLOI"'CHARTS The +d1Io{rin9 pages contain proceEs floucherts events thet oc€ur in the Nl'lI Bnd IRC interrugt

O P E R A T I N GS Y S T E HC U 1 6 5 5 5 - -

sho{rin9 the m€in DroreEssE.

gection

6 113

OPERATINe SYSTEM CO16595 -114

Section

6

NMI INTEBRUPTPROCESS

OPERATINcSYSTEIIc016559 --

S.ction

6

7

SYSTEd INI T IAL I ZATION

Section 7 diEf,usses the detsils of the po{rer-up and 5 9 5 t e t n i e s e t p r o c e s s e s . T h e p o r r r e r - u pp r o c e S S u r i t l b e e t p l a i n e d first, and then the sgsteo reset process uitl be explained in teros of its difference6 +rom the pouer-lJp pro.eEs. Eoth poure.-up (elEo calted coldEt€rt) end pressing CSYSTEM RE . SETI (uar.tn5tait) rrill cauEe 6gstem initiatization: In addition, ther€ ate vectoi5 for. these p?ocesseE at E474 tEg6teft reEet) and E477 (polrer-up) so thet theV can be uEer-initieted. The pouei*rp initializ€tiDn pro.€ss is a suoerget of rne sgstem reset initj.alizstion process_ porrer-up initializeE both t h e O S a n d u g e r R A Mr e g i o n s , u h e r e a s E g E t e m r e s e t i n i t i a l i z e E o n l g t h € O S R A Mr e g i o n . I n b o t h c a s e s , t h e O S c a l l s t h e o u r e r level softnsre initialization entrg point6 eIloU the applicdtion to initialire its oun vari€b1es. P r e s 6 i n g t h e I S Y S T E HR . ESETI teg p.oduc€s en NMI interrupt. It doeE not perfor{rl a 6502 chip-ie5et. I+ the processor is locked u p , t h e I S Y S T E MR. E S E T I k e g c a n n o t b e s u f + i c i € n t t o u n l o c k i t , e h d t h e 6q€tem rnuet have pousr cgcled to clear the problelll.

PAHEF-UP INITIALIZATION

(CoLDSIART) PROCEDURE

The OS perfor{t5 the follouing functj.onE i.n the ordeF shorrn, es pert of the pouer-up initiElizEtion proceEs: 1. The follouing

650A proceEsor stateE are Eet:

o

IRO interrupts

o

The de( irnal flag

o

The itack

a.e diEebled using the gEI in6truc tion.

pointer

iE c le€red using the CLD i.nstruction. is

The OS eets the uermst:rt

116

set to iFF. flag

h | A R M S T| O O O B I t o O ( f a I E e )

OPERATINCSYSTEI'ICO16955 --

Section

7

The OS tegts Ca.tridqe

to see i*

a diagnostic

cartridge

is

in the A slot:

Bddregs BFFC = OO?

Th€ ftemorg et BFFC i5 not RAM? Ait

7 ot the bgt€ at BFFD= 1?

If all of the above teEts are true, then control ic Dassed to the diegnoEtic certt'idge via the vectoi et SFFE. No return iE erPecte{t. 4 . T h e U S d e t e r f t i n e s t h e l o u e s t m e m o r qa d d r e s 6 c o n t a i n i n g non-RAH, bU teEting the first bgte of ev€r{, 4K ,,block', to see if the content cen be codrpleoented. If it EEn be compl€anented, then the oritinal value iE restored End testinq continues. I+ i t c a o ' t b e c o n F l e m e n t e d r t h e n t h e c o n t e n t i s i s E u t t l e dt o b e the first n o n - R A l . ,al d d r e 6 E i n t h e E g B t e n . T h e | 4 S B o + t h e addreie iE Eto?ed tenpofa!ilq i n T R A M S Zt O O O 6 l . 5. Zero iE stored to all of the harduare reg ist6r EddresEe6 ghoun b e l o u ( m o s t o f t h a t a r e n . t d € c o d e d b 9 t h e h a r d u r € r et : DOOO thl'ough DeOO t h. o'rg h D3OO through D 4 O Ot h F o u g h

DOFF DaFF DSFF D4FF

The OS cle:rs RAh fio.n location deteioined in step 4, dbove

OOO8, t o

the

a d dr e g g

7. The def6ult value for. the,,nonrattr.idge" control vector D O S V E CI O O O A I i s s e t t o p o i n t t o t h e b 1 € € t b o a r d r o u t i n e . A t the end of initiali!ation, control is Dessed throuoh this vectol. i+ a cartridge does not tEke Eontrol.

B. T h e r o l d s t a r t

flag

C B L D S Tt 0 2 4 4 l

i6 Eet to -1

(Iocet

use).

T h e s c r e e n o a i g i n 6 s r e E e t : l e f t . n t s r g i n= 2 , r i g h t n € r g i n = 39, for a 38 charaeter phgiical tine. The nsxi.munlinF gize of 40 f,hal.€.ter5 can be obteifled bV setting the marqin6 to O and 39. The OS insef,s the Ieft Dargin beceug€ the turo left|l}osr columns of the vid€o picture on meng television 6et6 ai€ not entirelg vi6ible on the Ecreen. 1O. The interrupt R A I ' Iv e c t o r s V D S L S T t O e O O l t h r o r r g h V V B L K D C O e Z 4 l ere initiali!ed_ See Section 6 for the initialization values. 1 1 . P o r t i o n s o l t h e O S R A l , la r e s e t t o t h s i i a s s h 6 u n b eI o u : O P E R A T I N CS Y S I E M C O 1 6 5 5 5 - -

r.equired nonzero velues

Se€tion

7 LL7

o

T h e I B R E A K I k e ' J f l E g S R K K E Yt O O l 1 l = - 1

o

The top of meftorg pointer MEI'ITOP toeEsl = the louresE ( f r o n o n - R A l , le d d r e E s step 4), HEI'ITOP uill be alter.ed lete? {rhen the Screen Editor i.6 opened in step 19.

o

The bottom o+ oenor! pointer MEhLO tOZE7l = O7OO, MEl,lLO can be €h€nged later if there is either a diskett€- or cac6ette-boot oDerEtion,

o

The +ollouing

reEident ioutineE

(+alse).

are called

for. initialiration:

S c t ' e e n E di t o r D i B p l a { H a n dl e r K a g b o a r d H a n dl e r P r i n t e r H a n dI e r C a g s e t t e H a n dI e ! ' Centi€ I I/O Monito" (CIO) Seiial I . / O l . l o ni t o r ( S I O ) Int€rr.up t p.oc egsor o

Th€ tSTARTI teq is chec*ed, and i+ preEEed, the cassEtte-boot request *lag CKEY tOO4Al iF set.

12. 69 0A IRO inte"ruptE

€re enabled using

thE CLI instruction.

1 3 . T h € d e v i c e t s b l e H A T A S Sl O 3 1 A l i s i n i t i € 1 i z e d to point to the r€sident handlers. See Section I +or inform6tion r.€latino to th€ Device Handlei'tEbte. 14- The Eer.tiidge slot dddresseE fo. certiidges I and A are era|nin€d to deterfiine if cartridge6 E?e ingerted, if RAMdoes not ertend into the c€itridge eddt.eBsEpece. If the ronteDt of location 9FFC is re.o, then e JSR is ete,t!t€d through the v€ctor at 9FFE, thus initiElizing aartridge (8". The cartridge is expected to return. If the content of location BFFCiE refo, th€n e JSR is erec!ted through the vector. at BFFE, thus initi:lizing "A". The cart.idge is expect€d to r.eturn. ceitiidge 1$. IOC8 l+O is iet op for an BPEN of the Scr€en Editor (E) and t h e O P E Ni s p e r f o r m e d . T h e S c r e e n g d i t o r u i 1 1 u s e t h e h i g h e s t p o r t i o n o + R A M+ o r t h 6 s c i e e n e n d u i l l adJUst ilEHTUp aErordinglq. If thi6 oper.ation shoutd fail, the entire initialization proeesg is repsated. 1 6 . A d e l a { i s a f f € c t e d t D a s s u r e t h a t a V B L A N Ki n t e r . u p t h e s occrrr.ed. This is done Eo th€t the Ecreen uill be e6tabliEhed be + o r e c o n t i n ! i n g . 17. lf th€ r€6sett€-boot then e cEEsettr-boot 118

request flag is set (6es Etep 11 :bove), opsiatlon is etteinpted. See Section 1O

OPERATINe SYSTE}.{CO16955 -*

Section

7

for

of the caE6ette-boot operetion.

details

18. If €nrj of the thrse conditionE 5t€ted belou exists, attempt iE ftade to boot frotn the disk. IheFe €re no c€rtridges

in the 91otg.

Cartiidgs

B iE inEerted Bnd bit

O of 9FFD is

1.

Cartridqe

A i5

in5erted and bit

O o+ EFFD is

1'

See Section 1O for' deteils

an

operetion'

of the di5tette-boot

1 9 . T h e c o l d s t € r t f 1 6 g C O L D S Ti E i e t e t * o i n d i c a t e coldstert process uent to cotnpletion.

that

the

procesE is nou,cotrplete. €nd the 20. The i'liti€li2ation co'ltr'olling application i5 nou,determined via the temeining Etep5. If there i6 sn A Eaft?idge inserted End bit-2 of BFFD is then a JMP i6 sxecuted thr'ough the vector at BFFA

1'

Ur, if there is 3 B cartridqe inscrted .nd bit-e of 9FFD iE gFFA' 1, then a JMP is executed through the vector at o t ' , € J u m p i s e t e c u t e d t h i o u g h t h e v e € t o r D O S V E Ct h e t c a n ooint io tha blEc&boa.d routine (default case)' caEsette D O S V E Cc a n b e booted to+tuate. booted 6oftuere or diskette i n SeEtion 1O' e x p l € i n e d € s E o f t u r a i e t h e b o o f , e d eltered bq

SYSTEM RESET INITIALIZATION

( I^IARI'ISTART I PROCEDURE

T h € f u n c t i o n s l i E t e d b e 1 o u ,a r e p e r f o i i n e d , i n t h e o r d e r s h o u n ' a 5 procesE: pert of the 6!rten r€set initializetion A. Same aE po[rer-i]p 6tep l' B. The {rai&5tart

+ 1 e g t ^ r A R l ' 1 St O TOOSl is

C. Same a6 pou,er_up stePE 3 thtough D. os RAH is

zeroed +r'on locations

E- S€fte a9 pouer_up 6tepE 9 through F.

5et

to -1

(true}.

5. OeOo-o3FF and oolo-oo7F' 16.

If a casEette_boot uas EUcaessfullq toopleted during the polrer-up initialization, then a JSR i5 exeEUted thtough the Section 10 for details of the S e e t O O O 2 l . veEtor CASINI p l ' o c e 5 5 . c€69ette-boot O P E R A T I N eS Y S T E MC O 1 6 $ 5 5 - -

Section

7 119

e. Sameas pouer-up step 18, €xcept in6terd of bootinq rne diEkef,te Eoftu€re, a JSR is executed thrrugh the vector DUSINI tOOOCIif the diskette-boot uaB succeEsfuttg co|npleted during the Poorer-upiniti€lization. See Section 10 +or details of the diBkette-boot pror€ss. H. Sa,neas pouer-up steps

19 End 20.

Noto that the initializEtion pioEedures €nd n€in entrie6 fo? all softual.e entities aas executed €t ever.g sgsten reEet as uell aE at polr€r up {EEe stepE 14, t7, 1A, 2O, F end G}. If the u s a r - g u p pI i e d i n i t i E l i z € t i o n / 6 t s r t u p c o d e m r , s t b e h a v e d i f f e r e n t l q in l.ecponse to sqstem reset than it doe5 to po{rer-up, then the 0 r a i . n s t E r t f l a g W A R I I S Tt O O O E l s h o u t d b e i n t e r r o g a t e d ; I I A R H S T= O fteang pouer-up entr.V, else sgsteft r€set entr.!.

120

OPERATINe SYSTSI'{COl6555 --

Seition

7

B

FLOATING POINT ARITHIIETIC PACKAEE

This section describeg the 8CD flo€tinq point (FP) p6ctage that i.s resident in the OS 80l'l in both th6 dodels 4OO and 8OO. The floating point peckage m€intainE numbers inter.natlg es 6-b{te quantitieE: a 5-bgte (10 BCDdigit) n€nti6sa uith a 1-bqte erpon€nt. B C D i n t e r n a l r e p r € s e a t a t i o n t r r a Ec h o l i e n s o t h a t d e r i o a l divi9ion {rould not leEd to the rounding er.rors tqpiEEllV found in b ina!'U repre€€ntat i on inplernentations. The paakage pr.ovides the follouing

operetion6:

ASCII to FP conversionF P t o A S C II c o n v e r s i o n . Integ er to FP converEion. F P t o i n t e g e i c o n v e r si o n . FP add, subtr€ct, |nrrltiplq, dnd divide. FP logar'ithm. erponenti6tion, and polrrnofiial evaluation. FP zero, load, stor€, €tnd move. A floating point operation iE pei+orned bq csllinq one o* the provided routines (eEch et E +ired address in ROM'€fter having set one or more flo€ting point pseudo register6 in RAM. The resolt o+ th€ desired operation uill also iovolve +loating point pseuda register6. The prinerg pEeudoiegi6ter's are describ€d belou €nd their eddreEses given {rithin the s{uere brac|(€ts:

I I P E R A T I N Gg Y S T E H C O 1 6 5 5 9 - -

SEction

E

F R O C O O D 4 I= FRl IOOEOI = F L P T R T O O F C :=

6-bqte inteinal foim of FP nuftber. 6-bqte interntsI foin of FP nuftber?-bgte pointer (1o,hi) to e FP. nufib et,

I N S U F Ft O O F 3 l = z - b q t e p o i n t e r ( l o , h i ) to an AScII tert brr+fer. CIX [OOF2l = 1-brJte index, used a€ offEet to b!f+e!' pointed to bg INBUFF. L B U F F C O S A O I= r e € u l t b u f f e r f o r t h e F A S C i o r r t i n e . FUNCTIONS,/CALL I NE SEOUENCES Desrriptions of the6e +IoEting point routines a9€lme that a pseudo regi6ter i9 not alteied bg a given routine. The nlmberE in Equare brdctets Irxxx] are the ROI'e I d d r e E E e Eo f t h e ro!tineE.

Point Conveision (AFP)

AgCII to Floating

Function: Thig r.outine ta&es en ASCII BtI.ing as input and pioduEei e floating point number in intErnal fofn. C a I l i n 9 s e q u e n ce : I N S U F F= p 6 i n t e r t o b u f f e r c o n t e i n i n g t h e A S C I ! r a P a E E e n t a t i o n o f t h e n u f t be r . CIX = the buffer offset to the fi"st bgf,e o+ the ASCII nu bet. JSR BCB

AFP TDBOO] first bqte of ASCII number is

FRO= flo€ti.ng point n{]mber. CIX = the buffer o+f5et to the first n u D be r .

invalid

bgte s+ter

the ASCII

AIgorithfn: The routine t€kes bqtes frofl the buffer until it encountets e bgte thEt cannot be peit of the number. The bqtes scenned to that point €re th€n €onverted to € +loating point number. I+ the first bgte encount€red is inval id, the carl.g bit iE s€t as € flag.

Floating

Poirt

to ASCII C!nver.sion (FASC)

FL,nction: ThiE r'orrtine converts a floatinq i n t e i ' n a l f o r o t o i t E A S C II r e D r e s e n t a t i o n . O P E R A T I N eS Y S T E I ' cI o 1 6 5 5 5 - -

point

nunber from

section

E

Calling

6equenre:

FRO= fl06ting JSR

print

nunber'.

FASC IDAE6]

I N B U F F= p o i n t e i t o t h e f i r s t bgte o+ the ASCII nutnber.. The lEst bgte of the ASCIT repfesantation ha5 the most eignificant bit (Eign bit) set, no EOL follorrs. Algoiithm: The routine converts the nu ber froo its internel floEting point r€pisEentation to a pr.inteble for.m (ATASCII). The p o i n t e . I N B U F F' r i l l p o i n t t o p € r t o f L B U F F , u h e r e t h e r e s u l t i E 5tor.ed.

Integei _'

to Floating

Point Conversion (IFP)

Function: This routine converts a a-bgte unsigned integer 65535) to floatir|g point internal represent€tion.

(O to

C a1 1 i n 9 E e q u e n ce : FRo = integer JSR

( F R O + O= L S B , F R O + I = H 5 8 ) .

IFP [D9AA]

FRO= +loating

Floating

Point

point

repreEent€tion

of

inteqer..

to Integer Conversion (FPI )

Function: This io!tine €onvertg a positive floeting point numb€r fr'om its inteinal repreEent€tion to the nearest 2-bgte integer. C€l I ing sequence: FRO= +loeting JSR BCS

point

number.

FPI TD9D2] FP number is flegative or >= 65535.5

FRo = z-bqte

integer

( F R O + O= L S B , F R O + I = t v { 5 )8.

Algoritho: The r.o!tine peffoTmE tr.ue rounding, not truncation, dur'ing th€ aonver€ion pioce6s.

U P E R A T I N eS Y S T E T C 1 O16555 --

Section

I t23

Floatitlg Pr int

Addition

(FADD)

Function: This routine edds trro floeting the resul.t for dut-of-r€nge.

point

nuftbers end check6

C e l l i n O s e q u e n re : FRO= floating FRr.= floating JSR BCS

point point

nunber. numbei.

FADD IDA66] out-of-range

resu I t.

FRO = reEult of FRO + FR1. FR1 iE e l tered. Fl oeting Point Subtraction

(F$UB)

Function: Thi6 i-outine subtraEts tuo ftoating checls the l'eirlt +or out-of-ran9e. CaIling

point

nuobers and

s e { u e nc e :

FRO= floati.ns FR1 = flosting JSR ECS

point tninuend. point subtrahend.

FSUB TDA6O] o!t-of-ranqe

result.

FRO= r€sult o+ FRO- FR1. FRt i3 €ltered.

Float ing

Point

l . l uI t i p 1 i c a t i o n

(FMUL)

Function: Thii ioutine multiplj.eE tuo checkE the re!ult for out-of-range. Calling

floating

point

nufibers end

Ee q l e n c e :

FFO= floating FR1 = floating JSR BCS

point multiplier. point multiplicand.

FMUL TDADB] out-of-ran9e

r esu 1t.

FRO= result o+ FRO* FR1. FR1i5:Itered.

O P E R A I I N OS Y S T E MC O 1 6 5 5 5 - 124

Sertion

I

Fl oet ing Foint

DiviEion

(FDM

F 0 n c t i o n : T h i E r o u t i n e d i v i d e 6 t u o f l o a t i n g p oi n t n u m b e r s a n d checl6 for division bq rer-o and for result out-o+-rtsn9€. Calling

s e q u e n ce :

FRO= +loating FR1 = floeting JSR BCS

point point

dividend. diviEor.

FDIV CDBzA] out_of-iang e r e 5 u I t

or diviEor

iE z€ro.

F R O= r e s u l t o + F R O. / F R 1 FR1 iE al tered.

Floating

Point

Logal.ithm6 (LOG snd L8e1O)

Function: TheEe ioutine5 tale of a floating poirlt nunber.

th€ natlrel

or bese 10 logerithms

C a I I i n g 6 e q u e n €e : FRO= +loating

point

numbe..

JSR

LOC IDECD] for

gc5

LOGlO tDEDll +or baEe 1O logarith!r neget ive nurnber or overflour.

FRO= floating point FRI is al tered-

naturBl

logarithm

logari thm.

Alqorith|n: Both logarithfn! €re +i.l.st computed es baEe 1O 1o!€rithm6 uging a 1O tet'm polqnomial approxiflation; the nBtur.al logarithm is computed bV dividing ths bsse 10 result bV rne €onstant LOO1O(E). The logaFithln of a number Z is coflputed eE fo11o{rrs: F n ( 1 C t, r + Y ' = Z u r h e r ' e1 < = F 4 1 0 ( n o r m a t i z a t i o n ) . L = L C I C l O ( F )b g l O t e r m p o l g n o m i e l e p p r o x i n a t i o n . LOOIO(Z) = Y + L. LOO(Z) = LOOrO(Z) / LOclOre). NOTE:This routine doeE not ?eturn eh error' if the numbei inout i6 rero; th€ LOClOr.eEUIt in thi3 EaEe is spproxinatelq -1e9. S, uhich is not uEeful.

O P E R A T I N OS Y S T E MC O 1 6 5 5 5 - -

Section

B 1?5

Floating

(EXP and EXPIOl

Point Erponentiation

Flnction:

T hi E r o u t i n e

exponentiates.

C a l I i n g s e q r e n ce : FRo = floating

exponent (Z).

point

e n* Z

JSR

EXP IDDCO] for

JSR

EXP1O IDDCCI for

FRO= floeting point FR1 is a I tered.

10 *+ Z

result.

Algor'ithm: Eoth erponentials are comPutsd internallg {rith the ba6e e erponential uEing the identitg: e ** X = 10 ** ( X ir LOClO(e) ). The beEe 10 exponential 10 ** X = 10 ** integer portion

is €valu€t€d in turo parts

as base 10,

using the identit!:

(I + F' = (1O ** 1) * (1O *+ F' -of X and F i9 the fraction.

uhere I

i5 the

The teim 1O +tt F iE evaluated using a polgnomiel epproxi.nation, €nd 1O r*tt I is a stiai.ghtforuard modi+ication to the +loating point exponant, Flodting

Point Polgnooial Evaluation

Function: This routine ev8luation.

(PLYEVL'

p e F f o l . m sa n n d e g r ' e e P o l g n o n i € 1

C e l l i n g r e { u e n Ee : X,Y = pointer (x = Lsa) to 1i5t o+ FP coef+i.lentE (A(i)) ordel'ed frorn high orde'. to Iou otder (sir blrtes Per' coefficient). A = nu{nbero+ EoefficientE in 1i5t. FRO= floating point independent vdriable (Zl. JSR BCS

PLYEVL TDD4O] over+1orr or other

eriot.

FRO= reEult of A(n)*Z*t+n + A(n-1)*Z**n-l A(O). FRl i6 altered.

...

+ A(1)*Z +

A l q o r i t h m : T h e p o l g n o n i e l P ( Z ) = S U H ( i = Ot o n ) ( A ( i ) * Z * * i ) cooputed u6in9 the Etendard oethod shoun 6elou,: P ( Z ) = ( . . . ( A ( n l r + Z+ A ( n - 1 ) ) * Z + . . .

+ A(1))*Z + A(O)

O P E R A T I N eS Y S T E I IC O 1 6 5 5 5 - -

Section

g

i5

Clear .-

FRO ( ZFRO)

Function: This roltine to all zero6. Calling

6et6 the contents of psesdo register

FRO

Eequence:

JSR

ZFRO TDA44]

CIear Page Zer.oFloating

Point Number (ZF1)

Function: ThiE routine 5et6 the contents of a .ero-page floating point nuober to alI zeioes. C€Iling

gequence:

X e Zero-page eddress o+ FP number to cl.ear. JSR

ZFI

TDA467

Zero-page FF number.(X) = zero.

Loed Floating

Point

N u m b e r t o F R o ( F L D O Re n d F L D O P )

Funrtion: The6e foutines load pse!do regi:ter floatihg point nunber Epecified bg tha.alling

FRo rrith ti:e sequence.

C € l I i n 9 Ee q u e n ce E : X,Y = pointer' (X = LgB) to FF number. JSR

FLDOR IDD89]

FLPTR = pointer JSR

to FP nunber.

FLDOP TDDAD]

FRO= flo8ting point nunber (i.n either ca6e). F L P T Ra p o i n t e r t o F P n u m b € r ( i n e i t h e r c e ; e ) .

T]FERATINGSYSTEM c016555 --

Section

I

Loed Floating

Point Numb€r to FRI (FLDIR snd FLDIFI

the Function: These routines Ioad p6eudo register FR1 tith f l o e t i n g p o i n t n o m b e rs p € r i + i e d b g t h e c a l l i n g E e q u € n c e . Calling

sequences:

As in prior deEcription, except the result goe6 to FR1 inEtead of FRO. FLD1R tDD9Bl and FLD1P [DD?C1.

Stot'e Floating

P o i . n t N u n b e r F t o n F R O ( F S T O R € n d F S T O P)

FunEtion: These routines stor€ the contents of pse!do I'egi6ter FROto th. addr.esespecified b! the caIli.ng 56qu€n€€: C:IIing

E € q u e n ce :

As in prior des€riptionE, is 6toFed from FRO rether ANd FSTOP [DDAB].

l'love Floating

Point

except the floeting poi.nt nuobe? thin loaded to FRO. FSTORtDDATl

) Nuober Fiom FRO to FR1 (FMOVE

Function: This ioutine p s e ! d o r . e gi s t e i F R l .

nrovesthe floating

point

numbei in FRo to

Call ing sequence: JSR

FHAVE IDD86]

FRt = FRO

( F R Or e m a i n s u n c h a n g e d ) .

RESOURCEUTIL I ZATION T h e + l o a t i n g p o i n t p a c k e g e { r E e Et h e f o 1 1 o { r i n g R A H l o E e t i o n s i n th€ Eour6e of perforfiing the functionE desEribed in thig section:

OOD4th.ough OOFF ut /E tnfouon

u ) t -t -

A11 of these locationi ate av€ilable +ot piogram toding i+ goui progrem does not cell the floating point p€Ekage.

OPERATINo SYSTEI4CO16555 -L2E

Section

I

I MPLEI'IENTAT I ON DETAILS Floating point nu,nb€i6€re oaintained internallg €s 6-bgte quantities, uith 5 bqteE (10 BCDdigitF) of nanaiEEa and 1 bgte of erponent. The rn€ntisEa i9 allrags noroa!ized such thtt the most Eignificant bgte iE nonzero (note ,,bgte,,and not ,,BCD di9it"). The rnost 6ignificant bit of the exponent bqte provideg the sign +or the trt5ntiEsa; O $or po6itive and 1 for_negative. The iemai.ning 7 bits o+ the exponent bgts provide the exponent in excess &4 notation. Ihe r€Eulting n l m b € r l ' e p f e ! i e n t E p o u r e r , so f 1 O O decimal (not poorersof lO,. This storage format allolrs the mentiEs€ to hold 10 BCDdigits {rhen tha value o+ the erponent ig an even pou,er of 10, and I gCO digitg uhen the velue o+ the exponent iE an odd pouer o+ 10. The implied decimal point is al0rags to the inneiliate right of the fir'Et bgte. An erponent leEs th€n 64 indicates a number less than 1. An sxponent equal to or gre6tei than 64 represents a numbei equel to or greatei than 1. Zero is repreEented brJa zefo nantiBsa and a zero etponent. To test for a rEEUlt from €nrJ of the stenddr.d routines; test either tne exponent or. the first nahtissa bUte for zero. The abEol!te value o{ f1o€ting point n|JobersmuEt be greater than 10t'*-98, and less thsn 10**+98, or be equBl to zero. There iE per+ect sgfit|letrg betueen positive and nigative nuobers |llith the erEeption that negetive zero iE nev€i generated. The preciEion of aIl computetion6is nsintained at 9 or 10 deci al digits, but sccuracA iF sooeuhat t€E9 +or those +unctiohs invo),ving polqnomial epp?ori|nations ( logarithm €nd erponentiationl. Aleo, the probleos inhereflt in €11 floating pornt 6qstems are preEent hel.er for exa|nple: Eubtraeting tu,o verg neerlg eqlEt nu bers, adding nulnbers of disparate oagnitude, oa €ucceEsirnE of an{ operation, urilI a1l res,Jlt in a liss of 5!gni+i€ant digitE. An analqsis of the deta renge and the order o+ evaluation of etprs6sions fllsq be iequired +oi some t{peE of a p p1 i ( a t i o n 6 . The €xaftples belou conpal.e floeting point numbers {rith tn€ir inteinal rep!.essnt€tions, aE €n eid to undsrEtanding storege foirnat. All nunber6 pr.ior to thiE point hevs been eipreesed in decimal notation, but these exanples !ri1l use hexadeiimal n o t a t i o n . N o t e t h € t & 4 d e ci f l a l ( t h e e x c e s E n u | n b e r o f t n e erponent) iE 40 uhen exFressed in hsxadeciftel: N u m be r : Stored:

+ O .0 2 = 2 * 1 O + * - 2 - 2 * 1 O O * * - l 3F Oe 0O 0O OO OO (FP exponent = 40 -

N u f l be r : Stored:

-O. OA = - 2 * 1 O + * - 2 = - 2 * 1 O O * + - 1 F F O e O O OO O0 OO (FP exponent = BO + 40 O P E R A T I N GS Y S T E i 4C O 1 6 5 5 9 - -

1)

Se.tion

t) g

Nuftber gtored

+37.O = 3.7 * 1O**1 = 37 * 1OO**O 40 37 OOOOOOOO {FP exponent = 40 + O}

Nunber Sto.ed

- 4 . & O 3 1 2 4 8 ' b* 1 0 * + 1 . 1= - 4 6 . O 3 . . . * 1 O O + + 5 CS 46 03 01 24 A5 (FP €rponent = 80 + 40 + 5)

N u m b e r: o . o Stored : OO OO OO OO OO OO

(sPecial

Eese)

O P E R A T I N OS Y 9 T E H c o l 6 5 5 5 - 130

gettion

I

9

ADDING NEW DEVICE HANDLEfiS/PER IPHERALS

T hi 9 s e c t i o n d e s c r i b e s t h e i n t e i f d c e r e q u i r e n e n t E + o r a noniesident Device Handl€r. thet i5 to be accesEed via the Centr"€l (CIO). The S€rial bus I/O otilitg I/O utilitg (SIO) interface is defined +or thoEe hendlers thet utitize ths Seriel I/O buE. The I./O iubEgEtem iE organized uith three 1eve1s of softuare b e t u r e e ng o u a n d U o u r h a r d u a r e : T h e C I O , t h e i n d i v i d u a l d e v i . c e h e n dI e l . 9 , a n d t h e S I 0 . The CtO p€r+orrn6the follouing Logical

devire name to Davi.e Handler |n€ppin9 ton OpEN).

L/O Cont"ol gloct Logical

functiong:

(IOC8t fteintenanre.

record handIing.

U s e r b u f f e P h e n dl i n g . T h e d e v i c e h e n d l e r s a r e b e 1 o u ,C I O . T h e g p e r + o r f i t h e follotring +un.tionE: o n p o u r e r - u pa n d 6 g 5 t e o r e s e t .

Oevice initialization Device-dependent BrJte-€t-a-time

6upport

data

input

o f O P E Na n d C L O S E E o f l m a n o s . and output.

0€vi ce-dependent Epecial operations. D e v i E e - d e p e n d s n t c o l n f n € n ds u p p o r t . Devi Ee data buffei The SIO is at handlerE). It

nanage.nent-

the bottom level (for Serial I/O bus peripheral p e r f o r . | ' l st h e + o 1 l o u i n g f u n c t i o n 6 :

Control of a1t Ser.ial bus I/O. taotocol. 8us operation fetries

conforoing

to the bus

on errors.

Retsrn of uni+ied er.or'st6tus€s

on €rior

O P E R A T I N OS Y S T E MC O 1 6 5 5 5 - -

conditions.

Section

I 131

A 6eDttate €ontro! Ett'rrcture is interface, as f ollotlB:

uied +ot communic.tion at each Block (IOCB)

User/CIO

I/B Control

Clo/Handler

zero-psg€

Handle./$IO

Device Control

I A C E ( Z I O C B' EIock (Dc8)

OPERATINGSYSTET'ICA16$55 --

13e

Section

9

I i

uger p r'og rEn

I I --------------*-----*------+

+---------+ ! IOCB.E

| **++*t1* | * |

I DCB +---------+

+---------+

l*

.*

I

zlocB

+---------+

I

lDevice i lable

I i

+----

+---------+ * * iDiE* Filel i Manager l-----+

i

+---------+

i i !

+------------+------+------+--+-+---------+ _ t P r i n t e r i i C a s E e t t e l i Handler i i Handler I +--*------+ +---------r

I

DCB

i . . . I Hand l er +---------+

+---------+ I K e gb o a r d i I H a n d1 € r i

i i

i DiEk i i Handler. I

l****r++r+ j{.+ ! SIO i Uti I itq +---------+

l^lhere:

+---------+

----

I I

shouE a control psth. shous th€ data structure

re{uired

for

a path.

Note the +ol1ouing: 1 . The Kegboard,/Displag/Screen

sIo.

Edito?

hsndlerg

don,t

The Diskette Hendler cannot be called directlg Tha DCE iE shoun tuice in the di€qreo.

Figuie 9-1

I/O

Subsgsteft Flou

fr.om CIO.

Didgram

OpERATINc 9YSTEtl CO16555 --

Section

use

9

DEVICE TABLE T h e d e v i c e t a b l e i s e R A f ' l - ! . e s i d e n tt a b l e t h a t c o n t a i n s t h e single*cha.arter' device name {e. g. K, D, C, etc). and the handler eddress foi each o+ the hendlerE knoun to CIO. The table is initialized to contain entries +oi the foltouj.ng resident handlersr Kegboerd (K), Displag (S), Screen Editot' (E', Cassette (C). end Print€r. (P) at pouer-!p and 6{Etem reset. i n s t a l l € n e u h E n d I e r , g o r n ep r o c e d u r e m u s t i n s e r t € d e v i ! e t e b l e a+ter the teble iE initialized. The teble

+ornat

H A T A B S[ O 3 1 A ]

Figure

9-2

To entiq

iE shourn belour:

+----------------+ i devi.ce nams r----------------+ I handler vector + + i table eddress +*---------------+ I mor'e

i I I

-+ I : +- one entrg i i -+

I

I

entiie6

i

i

zero +ill

to

!

i

end of table

I

D€vice Table Foift€t

T h i s 3 8 - b g t e t a b l e u i 1 1 h o l d € n € x i , n u | no + 1 2 e n t r i e E , u , i t h t h e last 2 bgtei being zero. CIO EcanE th€ table from the end to the beginning (high to Iou addresE), so the entrg nearest the end of the table 0rill teke precedence in Eese of nultiple o c e { r t l e n c e 6 o f a d e v i r e n a m e .The device naoe +or etsch entr! is e single ATASCII rharaeter, end the hendler addres€ points to the hendler's vecto1. tab1e, thet tri.II be de6cribed in the +ollo0rino section.

CIO/HANDLER INTERFACE This 5e€tion de5€ribes the interface betueen the Centl'al I/0 utilittJ and the individrral device handlerE thet are repreEented in the Device Tabl€ (a6 deE..ibed in the preceding Ee.tion). O P E R A T I N CS Y S T E I ' C | O16555 --

Section

9

C a1 1 i n g H e r h a n i s m E a c h h a n d1 € r h e 6 a v e E t o r

Figure

9-3

table

a E shoorn bElour:

+ O P E Nv s . t o r +---------*------+ + CLUSE vec tor +----------------r + OETBYTE vector +----------------+ + P U T B Y T Ev e c t o r +----------------+ + OETSTAT vec tor +----------------, + S P E CI A L v e c t o r

+

+ JMP init code + +------------'---+

+ +

Handl€i

( lo|l, ed d l.ess l

+ + + + + (high eddressl

V€ctor. Table

The devi{e tabts entr.U +or the handter pointE to the first brJte of the vectoi table. The firEt €ir entries in the tabte aie vectors (to,hi) that c o n t a i n t h e € d d r e s s - 1 o f t h e h t s n d 1 e ?r o ! t i n e t h a t h a n d l e s the indicated fun€tion- The seventh entrg is a 650A JMp instl"uction to the hendler initiali!ati.on routine. CIO uEeE onlq the addresses conteined in this table +or handler. entrg_ g a c h u s e r . / C I 0 E o m m a n dt r a n g l a t e g t o o n e o r m o t e . s l t s to one of the handle. entrieE de+ined in th€. veEtor tab1e. T h € v e e t o f t a b l e p r o v i d e s t h e h a n d l e r a d d t . e s E e €f o r c e r t e r n fired functions to be perfo.med to CIO. In addition, ooerarlon paramet€rs also oust be pa66ed foi most +unction6. patamerer pEssing i6 acconplished using the 6902 A, X. and y reqister6 and an IOCB in page O narned ZIOCB tOOaOl. In oeneral., l.eoister A is used to paEE dat€, r-egiBter X containE tf,e index to the originating IOCB, and regiEter y i6 {rsed f,o pe66 statuE infordlation to CIO. The zero-page IOCB, iE a .op! of tne originatinq IOCB, but in the coui6e of grocessino sotne comm€ndE? CI0 can alter the buffer addr.essend b;f+er length per'€n€terE in ZIOCB, but not in the origin€ting IOCB (Eee Section 5 for information relating to the ot.iginating IOCB). 5€e Appendix B fo? the standa?d status ieturned to CIO in regi6ter y.

bgte values to be

OPERATINe gYSTEt'l C016555 --

Section

9 135

The +ollotrinq EectionE describe the CIU/handler interfEce eE€h of the veEtors in the handler vector tabIe.

for

H a h d1 € r I n i t i a l i r € t i o n NOTEi This entrg doesn't appear to heve en{ function for nonreEident handlers due to a bug in the curr.ent OS -- the devi€e teble iE rle€red iD reEponse to sU6tefi reset as urelI as pouef-up. This pr.evehts this entrg point fron ever being €€l1ed. The rest of this gection discu6ie6 the intended use o+ this entr{ point. Confof ation uould be in oider to EIloll, cofipetibilit'J uith posEible co?r-ected versions of the OS in the +uture. The entrg u€E to heve been called on all dc€urrenEes o+ p o u r e r - u pa n d s g s t e m r ' s s e t , t h e h e n d l e r i s t o p € r f o r m initieliration o * i t 6 h a . d ! r a r - e a n d R A l . ld a t 6 u s i n g a l . o u t i n e f , h a t a s g u r . E s p r o p e r p r o c e s s i n g o f e l l C I O c o n r n a n d gt h a t f o l l o u r .

F u n ct i o n 6 S u p p o r t e d This section deEcri.bes the functionE asEocieted {rith the first sir vectorE fro{n the handler vector. tabl€. This section also presents a brie+, device-independent descr.iption of the C I 0 / h a n d l e r i n t e r + e c e € n d r e c b f l r m e n d e ad c t i o n s + o i e € c h f u n c t i o n vect or. I]PEN T h i E e n t r q i s c e l l e d i i 1 i e g p o n € e t o a n O P E Nc o m m e n dt o C I o . The h a n d l e r i s € x p e c t e d t o v a l i d a t e t h € O P E Np a r a d e t e l ' E a n d p e r f o r m ang !'equtred device initialization €sEocieted {rith a device OPEN. At handler entr.!,

the follouring parameterE can be of

intereEt:

X = index to o"iginating IOCB. Y = S92 (EtEtus = flnction not implemented b9 handler). I C D N A Zf O O 2 1 l = d e v i c e n u f t b e r ( 1 - 4 , f o . n u l t i p t e device h a n dl e r E ) . I C B A L Z . / I C B A H Z[ O O 2 4 , / O O 2 5 l= a d d r e s s o f d e v i r s , / + i l e n a m e specificEtion. I C A X l Z / I C A X 2 Z t O O a A . / O O A B= I d e v i c e - s p e c i f i c information. T h e h a n d l e r e t t 6 m p t s t o p e r f o r m t t r e i n O i c a t e d O P E Na n d indicates the statu6 of the operation bq the value of the Y r e g i s t e i . T h e r e 5 p o n s i b i l i t V + o r c h e c k i n g f o t . f t u l t i p l e O P E N gt o O P E R A T I N GS Y S T E i 4C O 1 6 5 5 5 - 13h

ge.tion

9

the sane deviEe oi h e n dI e r .

fi1e,

ohere it

is

illeoal,

lies

o,ith the

T h i s v e t t o r t a b l e e n t r g i E c a l l e d i n r " e s p o n s e t o s C L O S Ec o m m e n d to CIO. The hendler iE expected to r.elease ang hetd reso!,r.ee5 that r€lete gpecificallrJ to that device/fil.enarhe, and for. output fileE to: 1) send ang dat: 2) oart

rem€ining in handler bufferE

to the device,

th€ end of +i1e

3) upd€te ang a€societed directories, At handler entrg,

the folloaing

allocation

fiaps! etc.

paraneters csn be of

inte.est:

X = index to originating IUC8. Y = |l92 (statug = function not ioplemented bg handler). I C D N O ZC O O 2 1 1= d e v i . c e n u o b e l . ( 1 - 4 , f o r n u l t i p l e device handlers). I C A X I Z / I C A X ? Z T O O A A / O O 2 B =l d e v i E e - E p e c i + i c infor|natioh. T h e h a n d l e r . a t t e m p t s t o p e . f o r n t h e i n d i ( e t e d C L O S Ea n d indi.ates the 6tatu5 of the operation brJ the value of the Y ieg i s tel'. CIB relerges the associeted IOCBa+tei- the handler returns, ?egaidleis of the operstion 6tatus vaIue. GETBYTE .--

Thig vector. table entrU is c€11ed in r.esponseto a GET C H A R A C T E RoSr C E T R E C O R D€ o m d l e n dt o C I O . T h e h a n d l e r i E expected to r.etuin a Eingle bqte in the A regi6ter, or ieturn e?ior gtat!6 i.n the Y regiEter. At handler entrg,

an

the follou,ing peremeters can be o+ intere6t:

X = index to originating IUCB. Y = $9? (€tatug = *unction not ioplemented bq handler). I C O N O Zt O O 2 1 l = d e v i c e n u m b e r ( 1 - 4 , f o . m u l t i p l e d e v i c e h a n d l e r E ) . l C A y . l Z/ I C A X ? Z t O O A A / O o a B l = d e v i c e - s r e c i f i c i n f o r n t s t 1 o n . T h e h a n d l e r u i 1 1 o b t a i n a d a t e b q . + €d i ! . e c t l ' J f . o m t h e d e y i c e o r ' f . o r n s h a n d l e r ' _ m a i n t a i . n e db u f f e r 6 n d i e t u r n t o C I 8 u i t h t h e b u t e i n t h e A r'egistei and the operation Etatui in the Y register. O P E R A T I N CS Y S T E I 4C U 1 6 5 5 5 - -

S€ction

9 137

Handlers th6t do not h€ve shoit timeouts asEociated urith the ieading of deta (such a5 the Keqboard end CaEEettE Handleisl, m u s t n o n i t o r t h e I B R E A K I k e g f l a g B R K K E Yl O O 1 1 l a n d r e t u r n u i t h stetu6 of $8O uhen a tBREAKIcondition occufs. See Appendir L, 85, and Section 1e for a discuision of,CBREAKItel, fionitoring.

a

CIO checkE for reads fron device/fiIeE th€t heve not baen o!ened or have been opened for. output onlgi th€ handlet' {ri11 not be called t h o s e c€ s e s .

in

PUTBYTE T h i s e n t r g i E € a 1 1 6 d i n r e 5 p o h s e t o e p U T C H A R A C T E RoSr p u f RECORD c o m f l l e n dt o C I O . T h e h e n d l e r i 5 e r p e c t e d t o a E c s p t a s i n g t e bgte in the A registei oi return an error Etetus in the v ieg i 9ter. At hendler entrg,

the follouing

p a r " B m e t e r . c6 a n b e o + i n t e r e s t :

X = inder to origin€ting IOCB. Y = S 9 2 ( s t a t u s = f u n c t i o n n o t i m D I e t l r e n t e db t h : n d l e r ) . A = det€ bgte. I C D N O Zf O O 2 l l = d e v i c e n u m b e r ( 1 - 4 , f o r r n u l t i p l e d e v i r e h a n dl e r s ) . ICAXIZ/LCAX?Z [O02A/OO28J= device-specific information. The handler Eendg the data bUts dir€ctlU to the devi.e, or to e hendler-naintained buffer, and r€turns to CIO orith the oper€tion statu6 in the Y regieter. If a handler-maintained bu+fer fi11s, the h€ndIei uill Eend the bvffer€d dst€ to the device b€fore r e t u r n i n 9 t o CI O . C I O c h e c l s f o r W R I T E st o d e v i c e , / t i l e s t h a t h a v e n o t b e e ' l o o e n e d . or have baen opened for input onlg. The handler. u,ilI not be call€d t h o s e ca g e E , N o u , t h t s t t h e n o r m € 1 o p e r a t i o n o f P U T B Y T Eh a s b e e n d e f r n e s , a speciel case nu6t be added. Ang handler that ui11 op€r€te l|rithin the enviionnent of the ATARI AK BASIC lang!a9€ interpreter has a diffefent E€t of ruleE. Because BASIC c€ln ce11 the handler P U T B Y T Ee n t r r J d i f e c t l g . uithout going through CIO, the zero-page IUCB (ZIOCB) can or mag not have a rslation t o t h e P U T B Y T Ec a l 1 . Thei'efor€, the handler must oEe the outer level IOCE to obtain ang inforoation that uould noimallg be obtained f.om ZIBCB. Note E l s o t h a t t h e O P E Np l ' o t e . t i o n n o r m a l l q p r o v i d e d b r t C I O i s b{paEsed (i.e. P U T B y T Et o e n o n - O P E N d e v i c e / f i l e € n d P U T B Y T Et o a .ead-on 1g OPEN,.

134

O P E R A T I N CS Y S T E MC O 1 6 5 5 5 - -

S€€tion

g

in

EETSTAT This entr.q iE c€I1ed in respon6e to a OET STATUS codnend to CIO. The handler is expeEted to return foui bltes of statuE to melnor"q or return 6n erior statls in the Y reqistef.

At handler entrq,

the follouing

X = ind€x tg otiginating iop l enented bg handler ).

p a . a t n e t e r ' 5c e n b e o f

intereEt:

IOCB. Y = $92 (stEtus = function

not

I C D N 0 ZI o o 2 1 l = d e v i c e n u n b e r ( 1 - 4 , f o r m u l t i P l e d e v i c e h € n d l e r s ' . I C B A L Z / I C B A H Z t O O a 4 , / O O 2 5 l= € d d r e 5 3 o + d€vice/+ i 1enafiespeci+icetion.

tcAxlz/ rcAxzz

I O 0 " A / O O ? B 1= d e v i c e - E p e € i + i .

inf ormation.

Ihe handler 9et6 device 9t€tui information fro$ the deviae cont.ollei a n d p u t s t h e s t a t ! 6 b g t e s i n D V S T A Tt O A E A I t h r o u g h D V S T A T + 3 ,a n d f i n a l t q r e t u r n s t o C I O u i t h t h e o p e r € t i o n E t e t u s in ieg ister Y.

'

The IOCBneed not be opened not Elossd in order for gou the handlet. t o r e q u e g t C I O t o p e r + o t m e e E I S T A T U So p e r a t i o n ; g e E t i o n I foa a t h e r e r e s t r i c t i o n s . S e e ougt chec* uheie a?e S TATUS i n v o l v e d ! r i t h a G E T di6crrssion of the CIO sctiqn5 e l o s e d a n d n o te the ifipact a n d I O C B ' E , opetstiDn u6ing both open p arameter. a d d r e s E o f t h e b u f f € r of thi6 oDeration on the uee

SPECIAL

'-

This hsndler. entrg i5 !eed to suppoit e11 fun€tioni not hEndled f i l e R E N A H E ,d i s P l a g bg th4 other entr{ points, EUch as disl€tte c o l n t n e n db g t e v a l u e i E D R A W ,e t c . S p e c i f i c € l l g , if the 1OCB greater than tOD, then CIO orill uEe the SPECIAL €ntrq point. The h a n d l s r n u s t i n t e r r o g a t e t h e c o n r n a n db g t e t o d e t e f m i n e i t t h e requ€sted operation i5 suPported. At handtei entr{,

the follouing

patam.teiE tan be of

int€r'€5t:

IOCB. x = inder to originating ( s t e t u 6 = = Y $92 *unction not impleoent€d bg handleI.). d€vit€ ultiple I C D N A Zt O O 2 1 l = d e v i c € n u m b e . ( 1 - 4 , f o r handlersl I C C U M Zt o o z z l = c o o o a n d b g t e . ICBALZ/ICBALH IOO24/OOas] = bu+fei addre55. ICBLLZ/ICELHZ tOOaA/OO29! = buffer length. ICAXIZ / ICAX?Z |OO?A/ OO2B1 = ilevi€e-3p ec i f i c inf oifiati on.

OPERATINGSYSTEM CO16555 --

Section

I 135

The handler uill perfoifn the indicat€d opei.ation, if po6sible, and return to CI0 uith the oper€tion gtet!s in register y. Ihe IBCB need not be opened nor cloged in oider for uou t o r e q u e s t C I O t o p e r f o r i n s S P E C I A Lo p e r a t i o n , t h e h i n d t e r tnu6t che€k {rh€ie th€pe ar"e r.estriction5. See gection S for discuEEion o+ the CIO ections involved uith a SFECIAL op€tatiof| uEing both open and closed IOCB.s, and note the inpact of this on the u6e of the buffer address pitraoetei.

e

E r r d r . H a n dI i n 9 E r r o r h a n d l i n g h E s b e e n E i m p l i f i e d E o m e u h e tb q h € v i n 9 C I O h 5 n d l e o u t e r l 6 v e l e r r o r . s a n d h € v i n g S I 0 h s n d1 e S e r i € l b u 6 e r r o . t ' s , l e a v i n g t h e h a n d l e . t o p r o r e E s t h e r e m ai n i n g e i . r o r E . These efiot s inc l ud€: out-o+-renge par'ameterE TBREA(l teg abor t. Inv€ I id command. Read after end of file. The curren t hahdlel's reEporld to error s uging t h e + o t l o u i n g guidelines: Theg leep the racoverg simple (end therefore r€teatablel. Theg Do not inteiect instruEtionE. Ther, Iose es little

diiectlg

uith

predictable and

Uou +or resoverg

datE as pogsible.

Theq nEke a1t 6ttempts to naintain the ifltegritg of fite or i ented devic€ storags -- t h i s i . n v o l v e s t h E i n i t i a l desion o f t h e E t r u . t u i € 1 e l € f l p n t q e6 {rell a5 ef!.or }ecovei! teEhniques.

Resoufc e Al location Nonre6id€nt handle!.6 needing code end/or data spEce i n R A F Is h o u t d u6e the techniq!e6 !isted belour, to 65sure nonconflict {ri€h other partE o+ tfre OS, inrl!ding o t h s r n o E i e s i d e n t h e n dl e r s .

140

OFERATINOSYSTEH c o r 6 5 5 5 - -

SBetion 9

Zero-P€qe RAM _

Z e ? o - p € g e R A I ' Ih € s n o s p a f e b g t e s , a n d e v e n i f t h e r e u e r " e , t h € r e i5 no €tlo.etign p.ogrE$:ssiqnfienf, of s€hefle to Eupport nultiple the spare!i, There+ore, the nonresident htsndler must seve i|nd regtore the bgtei of zeio-page RAMit iE going to ure. The bgtes to u5e muEt be chosen c€re+ullV, €{rording to the *ollouing €riteria: The bqteg .annot be ec€eE6ed bg an interrupt

ro{Jti,ne.

The b9te6 csnnot be acceEs€d b{ eng noninterr.upt code betueen the time the handl€r modi+ieE the bgtes and then reEtor.es the origin€1 values. A simple seve/r.estor.€technique uould utilize the stack in a oanner 5imilar t o t h a t s h o { r r nb e l o u r : LDA COLCRS , (for Eranple) PHA ; SAVE ON STACK. LDA COLCRS+1 PHA LDA 9TA LDA STA

HPOINT COLCRS HPOINT+1 1 COLCRS+

r HANDLER'S POINTER.

XXX

(COLCRS),v

r D O Y O U RP O I N T E R T H I N G .

PLA 5TA PLA STA

; RESToRE ULD DAIA. CBLCRS+1 COLCRS

Note that the Displaq HandIer.ol Screen Editor Ehould not be c a l l e d b e f o r e r e s t o r i n g * h e o r i g i n a l v a l u e o f C O L C R S ,b e t a u s e C O L C R Si s s v a r i e b l e u 6 e d b u t h o s e r o u t i n e s . N o nz e r o - P a g e R A H There is no allocation schemeto support the assignflent o+ + i x e d r e g i o n 6 o f n o n z e r o - p a 9 e R A I ' 1t o e n q s p e . i f i c process, Bo the h a n dI e r h s E t h i e e r h o i c e s : 1.

l,lake a dgnamic alloc€tion

at

initieliretion

tifie

b9

a ] ter in9 MEt'lLO tO2E7l. 3.

Include the variables urith the handler handler'8. This still involveE slterino t h e h a n dI e r i 6 b o o t e d .

3.

If the handlei ieplaces one of the regident handlel.E (bq removint the resident handl€I.'5 entrg in the device table), then the neu handler €an u5e anu RAlilthat the

O P E R A T I N CS Y S T E MC 0 1 6 5 5 5 - -

for RAM-Tesident H E H L Oa t t h e t i r n e

Section

? 141

former.lg !'€s i dent

hend I er

tlou I d h€ve

uged

S t a r I S p a Ee In no5t caseE, there are no restrictions on the use of the Etac& bg e h€ndler. Hotl,ev€r, if the handler planE to push more th€n a touple dozen bqteE to the 6tacki then it should do e 6tack overf lo{r,test, and aluraUs leave gtacl gpace for interrupt pfocessing.

HANDLER,/SII] INTERFACE ThiE section describes ths interface betue€n Eerial buE devire handlers €nd the serial bu6 L/O utilitq (SIA). SIU coflpleteIg handle5 all bos transactions folIouing the device-independent bug pr"otocol. S10 i6 re6pon5ible for the fol1ouin9 functionE: Bus detE +or|net and tining Error

deteetion,

retries

fron

computer efld.

enal statuEes.

Bus timeout. Tr€nsfel

o + d a t a b e t u r e e nt h s b u s € n d t h s c a l l e r . E

buffer.

Calling Hechanis SIO has a Eingle entrg point SIUV tE459l for eII oDeretionF. The devi ce contro I blork (DCB) tO3OOl containE all pareneters oassed to SIB. The DCE c o n t a i n s t h e f o t l o l r j . n g b g t e s : D E V I C E B U S I D --

DDEVTC to300l

The bu6 ID of th e device is S I O ( s e € A p p e n d iI l r . DEVICE UNIT * --

Eet bV the

h€ndler. p.ior

to

celling

DUNIT IO301l

ThiE bgte indi€stes that of n unitE of d given d€vi ce EqPe to arceEs, and is set b{ the handler. prior to cElling SIO. This v a l u e u s u a l l q c o m e s f r o m I C D N O Z .S I D a c r e E s e s t h € b llrhose addr.es: is equal to the value of DDEVICotui D U N I T m i n u s 1 (the louegt unit nunber iE normtsllg equal to I ). -. DEVICE COHI.IAND

DCOMNDTO3OE]

The handler Eets thii bVte prior to celling SI0. It ui 1l be sent t o t h e b u 6 d e v i c € a s p a r t o f t h e c o r n o a n df r a m e . g e e A p p e n d i x I f o r d e v i c e c o { | r d r a n db g t e v a l u e s . O P E R A T I N CS Y S T E MC O l 6 g g S - -

Section

DEVICE sTATUs --

DSTATS tO3O3]

This hgte iE bidiiection€1. T h e h e n d l e t u r i I I u s e D S T A T St o indicEt€, to SIO 'rrhat to do eftei the rommend +r6me iE sent €nd a c k n o { r 1 e d g e d .S I O u r i l l u E e i t t o i n d i c e t e t o t h e h a n d l e r t h e stetu6 of the requested operation. Prior

to an SIO ca1li 7 +-+-+-+-+-+-+-+-+ lWlRl (J'tused +-+-+-+-+-+-+-+-+

o i

Wh€re: W,R = O,O indicate5 no data tran6fer. iE agsociated 0rith the operation. O,1 indicates a deta +rame i6 expected frol|| the deviae. 1,O indiEate6 3 date fr.ane is to be sent to the deviEe. 1,1 is invalid

A +t e r a n S I O c e l l :

o 7 +-+-+-+-+-+-+-+-+ I statuE code i +-+_+-+-+-+_+-+-+ See Appendir C for

the Fossible SIO operation 6tatus

HANDLER BUFFER ADDR€SS -Th€ hendler sets this or dastinstion buffer

EodeE.

DEUFLO,/DSUFHI TO3O4/O3O5]

2-bqte point€r. It indicatei the Eource for device data of st€tur infoiflation.

DEVICE TIFIEOUT _- DTIMLO 10306] Ihe hendle? sets thi5 bqte. It specifier the device timeout time in units a+ b4/6O o+ d second. For exatnple, a count o+ 6 speci+ies a ti.neout of 6.4 secondE. BUFFER LENGTH/BYTE COUNT--

DEYTLD./DBYTHI[O3OA,/O3O9]

The handler sets this 2-b!te count for the EUirent o p e t a t i o n , € n d i n d i c a t e s t h € n u . F n b eor f d a t e b g t e E t o b e ttan6fer.red into or out of the buffer. This paranetei is not t'eqlired i + t h e S T A T U Sb l t e t J a n d R b i t s e r ' e b o t h z e r o . T h e E e valuei indirete that no dat€ tr'EnEfet is to tale rlace. I ' { A R N I N G :T h e r e i s a b u g i n S I O t h e t c a u s e s i n c o r r e c t e E t i o n s { r r h e nt h e 1 a 9 t b g t e o f a b u f f e r i s i n a o e m o r { addr.esE endinq in $FF, such as 13FF, 4eFF, etc. T]PERATINOSYSTEII COl6555 --

5e€tion

9 143

AUXILIARY

INFORHATION..

D A U X 1 / D A U X E TO 3 O A / O 3 O B]

The handler setE these E-brJte6. The SIO inrludes thelll in condand +rade, theg have device-specific meaning€.

the

bu5

F u n c t i o n 5 S u pp o r t e d S I O d o e s n o t e r € d i n e t h e C O H M A NbD{ t e i t 6 e n d s t o t h e d e v i c e , becau5e el1 bur transactions ere expectsd to ron+orft to e univarg€l pr.otorol. Ths protocol includ€s three forfts, stated belou, (as 5een fiom the rofiouter ): Send comm6ndfnefie. gend commandfraoe

and gend dats fram€.

S e n d c o t n f t a n d+ r : m e e n d r e c e i , v e d a t a f r € r f l e . The velues of the t, and I c otlftand f or.m.

Error

bits

in the statug bgte Eelect the

H a n d1 i n g

SIO hendleE moEt o+ the Eeriel as ind i cated belolr:

buB errorE foi. the hdndler,

8 u 9 t i n e o u t - - S I O p r o v i d e s e u n i f o r . m E o m m e n df r : t n e a n d d a t a ft'ame ACK bvte timeout oe L/6O oC € seEond - O / + 1/he. T h e h € n d l e f E p e c i + i e s t h e n e x i m u m C O M P L E T bEg t e t i t n e o u t value in DTIHLO. gus errors -- SIO dete.ts snd ?eports UART overrun and fTeming errorE. The sen6ing of thess e!-rors in €rnl received bgte uill c€use the entire assoc;ated +rame to be conEidened bed. D€ta +rem€ rhesksufi error -- SIO validate5 the cherk6um on all ieceived data +raoes and qenerate6 a checksuo for €Il tr€nEmi tted fralnes. Invalid ?esponse +rofi device -- in addition to the er.ror conditions etated €bove, SI8 chec*E that th€ ACK end CDI'{PLETEie6ponses Ere pr.oper (ACK = S41 and CBI,IPLETE= $43,. ACK €tands +or a.lnouledqe. 8us op€rEtion retrieE -- 5IA lrill attempt one cornplete comnand retrg if the fiiEt attempt iE not err.or +ree, urherea complete conoand trV conslEts o+ up to l4 etteopts to send (end a c l n o d l e d g e t a c o l n m 5 n df ? a m e , f o l l o o e d b q € s i n g l s a t t e m p t t o O P E R A T I N GS Y S T E I ,C I 016595 -144

Section

9

rereive

the COI'IPLETE code and Fo5siblq

a dste

fraoe.

NOTE: There is a bug in the retrg logi€ for deta {trites, 6 ! c h t h a t i f t h e r o m m a n d+ i a l n e i 6 € c * n o u l e d q e d b g t h e but the datd +relne is not €cknouledged, then SIO rontroller, 0rilI retrq indefinitel!. Unified eil.or 6tatus code6 -c o d e s ( 5 e € A p pe n d i r C ) .

gIO provides device_indep€ndent erioi

SERIAL I/O BUS CHARACTERISTICSAND PROTOCOL This 6ertion describe6: o

o+ the ATARI 4OO The ele€trical .h€racteristiEE e n d A T A R I 8 O O H o r n eC o m t u t e r s E e r i a I b u E

o

lhe uss o+ the bug to send bUtes of dete,

o

Ihe organiztstion of the bqteE a5 r'frafte5" (records),

o

frames T h e o v e r a l l c o r D n a n ds e q u e n c e E t h e t u t i l i z e and i'€5ponie .b9tes to ptovide coftPUter/periphertsl co nonication.

H € r d u e r e / E l e Et r i c a I c h € i a c t e r i 9 t i c s The ATARI 4OO and the ATARI eOO Homs Codputers c o r n m u n i c a t eu r i t h p e r i p h e r a l d e v i c e s o v e r ' 3 1 9 , a O O b a u d asqnchronous seiial port. The 5eria1 port consists of a !eri€I D A T AO U T ( t r a n E m i E s i o n ! I i n e , a s e r i a l D A T A I N ( r e c e i v e t ) I i n e end other mi.6cellaneolE control lines. Data is tiansmitted and received tss I bitE o+ serial data (LSB pteceded bq € logi€ zero start bit and succeeded 6ent firEt) b g a l o g i c o n e e t o p h i t . T h e s e r i a l D A T AO U T i 5 t r a n s m i t t e d a g The poEitive loqic (+4v = one,/true/hi9h, Ov = zero/+alEe/Iou' Eei'ia1 SATA OUT Iine alu,egE assuroes its nFU 6tate uhen the e e t i a l C L O C KO U T l i n e g o e g h i g h , C L O C KA U T t h e n g o e e l o ! , i n t h e c e n t e i o f t h e D A T Ao U T b i t t i m e . An end vieu of the ge!'i.el buE connector Et the computer or peripherel is Ehoun belou (thE cable connectors u,o!ld of image): course be a nirrof

I O16595 -O P E R A T I N oS Y S T E I ' C

gection

I

2 o o 1 uhere:

1 2 3 4 5 5 7 a I 1O 11 12 13

= s = = = = = = = = = = -

4 o o 3

6 o o 5

A o o 7

10 o o I

1? o

o 11

o '3

c o d r F u t e i C L O C KI N . Eooputer CLOCI,(UUT. conputer DATA IN. OND. computer DATA OUT. GND. C0HMAND-. HOTORCONTROL. PROCEED-. +5v,/READy. ro.nputer AUDIO IN. +72v. INTERRUPT-.

FiguFe 9-4

Serial

8us Connector Fin 0€s€riptions

C L O C KI N i s n o t u 6 e d b g t h e p r e 6 e n t O S e n d p e r i p h e r 6 l s . T h i e l i n e E a n b e u B e d i n f u t u r e E g n c h r . o n o u sE o m m u n i c e t i o n s E € n e m e t i . C L O C KU U T i s t h e E e r i € 1 b u 5 c 1 o c k . C L O C KO U T g o e E h i q h a t t h e s t a r t o f e E E h D A T AO U T b i t E n d r e t u r n s t o ! o { , i n t h e n i d d t e o f each bit. DATAIN is

the Eerial

Pin 4 CND is D A T AO U T i s

bu5 data line

the Eignal/shield the serial

to the conputer.

ground tine.

bus dEts Iine

Pin 6 CND is the Eignal/Ehield

fron

the computer.

9l.ound 1i.ne.

C O i ' l t ' l A N Di 9 - normallrJ hiqh end 9oe6 lou uhen e command$raoe i6 b e i n g s e n t + r . o mt h e . o m p u t e r . MOTOR C O N T R A Li s lou= of +).

the c6ssette notor

control

Iins

(high=on,

P R O C E E Di-6 n o t u s e d b 9 t h e p r e e e n t O S a n d p e r i p h e r a l s , is pulled high.

thi5

tine

+ 5 V , / R E A D iYn d i c a t e s t h a t t h e c o m p u t e r r 9 t u r n e d o n e n d r e 6 d q . T h i E line can a16o b€ used as a +g volt gupplrJ of soma Eurrent rating foi ATARI periph€raIs on1g. A U D T Ot N a E c e p t s a n a u d i o B i g n a l f i o f i

L46

the casEette_

OPERATINOSYSTEI'ICC116599--

Section

9

+12V is € +12 volt per iphera I s onlg.

s u p p l { o f u n k n o u n c u r r . e n t .at ing for

I N T E R R U P T -i s n o t u s e d b g t h e p r e s e n t l ine iE rulIed hioh.

A T A RI

OS and p e r i p h e r a1 5 , t h i s

There ere no pin rees6ignments made in the Serial bus ceble, 5o pin 3, the conputer,E DATAIN line, i9 the 9el.irher.al.9 date output Iine, snd sinilarl'J +or pin S.

Seria 1 Fort Etectric€1 Periphe.al

gpecificationg

input:

VlH = 2. Ov rnin. VIL = O.4v lrlex. ItH = eo!e. n€x. @ V1H = 2. Ov Il.L = 5ua. fitsr. e VlL = .4v Periphel'al output

(open col lector

V O L = O .4 v m € x . @ 1 . 6 m a . VOH = 4. 5v min. urith external

bipolar ': lOOKohn putl-up

VccIREADY inp ut: V1H = a. Ov min. e I1H = 1oa. mar. V 1 L = O . 4 v l n €x . Input 9o€s to Iogic zero uhen open.

B U E C o m m a ngd T h € b u s p r o t o r o l g p e c i f i e s t h a t a I t c o m m a n d sf t o E t o r i g i n a t e + r o m t h e computer, and th5t peripherals uill present deta on the buE onl{ rlhen c o i n m a n d e dt o . E v e r ' g b u s o p e i a t i o n 0rill go to coopletion before (no ov€rlepl. An error detected at another bus oper.tion iE initieted p o i n t ang i n t h e c o o o a n d E e q u e n c eo i l l aboit the entiae Eeqoence. A bus operEtion consist6

of the +o11or!in9elelnentE:

Comnend frame from the comrute.t.. Artnouledgeftent (ACK) +rom the peripher.al. Optional

data f"e

e to or. from the rodrputei.

O p e r e t i o n c o m p l e t e ( C A H P L E T E f) r o m t h e p e r i p h e . a l . O P E R A T I N eS Y S T E I iC O 1 6 5 5 5 - -

Section

9 147

Coflnr3nd Ffafie The eeriel bus protocol provides for three tVpe6 of connandst l) data s e n d , 2 t d . t a r e c e i v e a n d 3 ) i r n n e d i s t e ( n o d e t a - - c o m m a n do n l u ) . T h s r e i B € c o f t m o ne l e n e n t i n € 1 1 t h ? e e t g p e 6 , e c o m m a n df F a m € conEisting of five bqtes o+ infornation sent froln the compuxer u h i l e t h e C O M H A N D l-i n € i 6 h e l d l o r ! . T h e $ o i m € t o f t h e c o m o € n d +ralne ls 5ho{rn b e Io{r: +----------------+ ! device ID

!

I coonand i r_________-______+ i aurilia!"g *1 I i EUxiliarg *e +----------------+ I chec&surl

! I

t----------------+

Figure 9-5

Seridl

Bus Comntsnd F?ame For,ne t

The device ID specifies thet of the 6eiial !us deviceE address€d (E€e App€ndix I +or a liEt of device tDs)T h e c o r n m a n db g t e c o n t E i n s E d e v i c e - d e p e n d e n t Appendir I for € list of deviEe commsnds).

Ths €uxiliaig

iE

being

aommand (Eee

b9te9 contain more deviEe-dependent infornation.

T h e E h e c k s u n b q t e c + n t a i n s t h e € r i t h | n e t i E E U mo f t h e f i i s t b g t e s ( u t i t h t h e c a r r V a d d e d b a €f t e f t € r e v e r g € d d i t i o n )

four

C o n , n a n dF r a o e A r l n o u r l e d g e The peripherel being addrerEed uould normallg r.espondto a c o m m a n df r a m e b g g e n d i n g a n A C K b g t € ( A 4 1 ) t o t h e c o n p u t e r , i * there is a probleo uith the romn€nd fr3tns, th€ peripher.al should n o t ? 6 s Do n d ,

Data

144

Frafie

APERATINe SYSTEI.ICO16555 --

Section

9

Follouing the Eommand f?amE (and ACKI can be an optionel fiame thEt i.E forltl€tted a€ shourn belou:

i

but€s

+----------------+ i c h e c* E u m

-

date

i I i

This deta fretue can originate €t th€ computer oa at the device contioller, depending upon the comnand.Curient device controllerE expact fired-lenqth data frames aE does the co||lputer', tlrhereth€ d6ta frame lenoth i6 a fired function of the device tqpa End ro|nmand. The €he€ksuo value in the deta fl'Etnei9 the arithfietic sum sf all of the frane dat€ pre€eding the che€kFUm, '!ith the carrg +rofll e a E h a d d i t i o n b e i n o a d d e d b € E l ( t h e E a m ea E f o l . t h e c o o o e n d frame). In th€ case of the cofllplter sending a d€ta fr€me to e peripheral, th€ peripheral is experted to gend an ACK i.f the data frEme i6 €cceptable, and Eend a NAK (S4E), or. do nothing i+ the date frame is unacceptable. See the +ir5t flouchar.t in Section 9. O p e r a t i o n C o n pI e t e

-

A peripheral is:1so e r p e c t e d t o 6 e n d a n o p e f a t i o n - c o M P L E T Eb g t e ( 9 4 3 ' 6 t t h e t i m e t h e c o n m a n d e do p e r € t i o n i s c o n p l E t e . T h e I o c a t i o n o f t h i s b g t e i n t h e c o t n m a n ds e q ! e n c e f o t e a c h c o o h a n d trtpe i.i Eholrn in the tioing diagranE in Section 9. If the oPeration cannot go to notmal, etror-+tee coopletion, the p e r i p h e r B t e h o ! 1 d r e s p o n d u i t h a n E R R O Rb ' r t € ( $ 4 5 ) i n E t e a d o f COMPLETE.

O F E R A T I N eS Y S T E MC O 1 6 5 5 $ - -

Section

9 149

Bus Titning This section p.ovideE tifiing disgia|ns for the three tgpes of to|nln€ndi€quence6: data send, data re€€iv€, end innediate. DATA SEND Ee{uanc e: coMhAND-

DATA OUT

I +--------+

I

+------+ i cnnd I ----+frame +------/

+--- / /---+ I data I +------/--+ +raoe

+-+

DArAIN

+-+

I .l------------

-----:

ACI( | | to

l t tl

|

I i t2

:-

ACK

CHPL

i i

i

|

t3

+-+

':--rr--:

t4

t5

D A T AR E C E M s e q u € n ce :

cot'$tAND-

i +--------+

DATA OUT

DArAIN

.\''/

I

I rlnnd i ----++iafie

+.-+

: :--,,--; ACK

+-+ +----/

i-i

l--------

-l:::

CI'IPL

OPERATINGSYSTEM CO16555 -190

/----+

Se.tion

I

I H M E D I A T Es e q u e n ce I

c{]flMAND-

i

i

+------+ i cinnd I ----+irafie +--------------

DATA oUI

+-+

DArA IN

+-+

'' '*.--...--..-..--t t-----l ACK

t0 Fi.qute 9-6

Serial

t1 t2

,;---------CHPL

t5

Bus Tirning Diagran

The conputer gene.ateE a delaq (tO) betureen the louering of COMI'IANDa n d t h e t r r n s m i E s i o n o + i h e + i r s t b u t e o f t h e r o d t h a n df ! a m e . computer tO (oin) = 75O nicroEeE. conputei. tO (mext = 1600 microsec. periph€ral peripheiel

to t0

(min' = ?? (max) = ?t

The cornputer gener€te6 € delaq (t1) betueen the tr€nstniEsion of t h e l a e t b i t o f t h e c o f t d r a n d+ t ' a m e a n d t h e r . a i s i n d o f t h e C O M I . I A N D I i ne. tornputer tl (oin) = 650 flic.oEec. c o m p u t e r t 1 ( m a x) = 9 5 O f t i c r o s e c . peripheral per.ipheral

t1 tl

(mifl) = ?? (ftar l = ??

The peripheral gsneret€r € delag (tA) betueen the r€lEin9 of C O t l t 4 A N Da- n d t h e t r a n s m i E s i o n o f t h e A C K b t r t e b 9 t h ! p e r i p h e r a l . EoopLrtert2 (tnin) = O nicroEeE. co|nputer tZ (mexl = 16 ftEec. per'ipheral t2 peripheral t2

(ftin, = ?? (&ar' = ??

O P E R A T I N OS Y S T E MC O 1 6 5 5 5 - -

Section

9 151

The co|nputer g€nerateE a delaq (t3) bstureenthe i.eceipt of the bit of le6t bit of th€ ACK bgte and the transmission of the first the data frafte bl the tornpoter. co|nDute. t3 conpLrte. t3

( m i n ) = 1 O O 0m i c r o s e c . ( n e x ) = 1 E } O On i c r o s e c .

peripher€1 t3 peripheral t3

(minl = ?D (rnar' = ??

The periphetal generates a delsq (t4' betueen the transrnie6ion o+ bit the last bit of the date frame and the receiot o* the fiist of the ACK bgte bg the co{rputer. co$Dutea t4 conputer t4

(oin) = B5O nicrosec. (mar) = 16 mEec.

peripher€1 t4 pe?ipheral t4

(min) = ?t (naxl * ??

The Peiipheral gener€teE a d€t€g (tS) bet{reen the the receipt of bit of the COI4PLETE the last bit of the ACK blte End the fir6t bgte bg th€ romputer. conputer tS (min) = aso fticfosec. corDputertS (fierl = 255 sec. (handler-dependent) peiiphe|,al t$ peripheral t5

(oin) = ?? (rlar) = N/A

HANDLER ENVIRONHENT Nonresident handler6 can be ingtall€d oannefE: 1. 46 booted goftuare

fron

e. Resident in e Eartridge 3. Dou,nloEd€d+rom € seritsl

in at

di5&ette

lEest three di+feTent

or EaEEette.

(A or B'. b!s

device.

This seation uill d i s r r . r 6 Et h e b e s i c o e c h s n i 6 l n s f o r h e n d l e r installation +or the6e envi.ronftents. In oider to fullq utilize infoFflation in thi€ section, uolJ mugt heve iead €nd onderstood follouing seations: Prografi environoentE R A Mr € g i o n l'lemorq dgnamics.

S!6ten initial i 16tion. Adding neu deviEe hendleri/peripherali P r o g ! ' a me n v i r o n { r e n t a n d i n i t i a l i r a t i o n UPERATINC SYSTEI,ICO16555 --

Sect ion SeEtion Serti6n Section Section gection Section

3 4 4 7 9 10 9

the the

B o o t a b l e H a n dI e " The distetteor ceEsett€-booted ioftlrare rrril1 insert the handler'6 vector table oointei and naoe to the device table uhenevei the booted Eoftlra?e'6 initializEtion entig point i9 ente?ed (on pour€r-up end s!5te|n !'e6et). Remeflber th€t both poue?-up and cgEtem ?es€t c1€ai the device table of all but the r e s i d e n t h a n dI e r e n t r ' i € 5 .

Cartr i dge ReEident Hendler The cartridge Eofturare uilI inseit the handl€r'E vectoi table pointeF and nafie to the devit€ t:ble uhen€var the certridge" initialiration entrg point i9 ent€red (on po{rer-up and sgstem reset'. R e l n e & b e r .t h a t b o t h p o u , e r - o p a n d € ! E t e | n r e t e t clEat' the device table of all but the reEident h€ndlei €ntrie5, thei€fore the device table .nuEt be r'€e6tEblished b'J the procedure upon everg entirj. handler-initielization

FLOT.ICHARTS The follduing pageE contain process flouahartg rhouring th€ SIO and p€ripherel actions for the Serial bus conrand forng.

O P E R A T I N CS Y S T E T C { O16555 --

Section

9 153

PERIPHERAL'SCOMIVIAND FFAME PROCESSiNG

OPERATINGSYSTEH C416553 -154

gieEtion

9

DATA FRAMETO PERIPHEFAL

OPERATINOSYSTEI'IC O 1 6 5 9 5- -

6sction I

DATA FRAI\'IETO COMPUTER

OPERATINo SYSTEI'iCO16595 -156

giection

g