Microprocessor 8085 By Shaheen Fatima

SEM INAR PRES ENTED B Y: Mrs. SHAHEE N F ATIM A LECT URE R I N EL ECTR ONI CS GOV T DEG REE S CIE NCE COL LEG E TUM KUR U. KAR NA TAKA S TATE .

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Introduction to Microprocessor  

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The Microprocessor is an electronic logic device having computational and data manipulation capabilities. Due to great invention in semiconductor fabrication technique, it became possible to fabricate the whole central processing unit of computer on a single small integrated chip called as microprocessor. The computer having microprocessor as central processing unit are called as microcomputers. A desktop computer and portable( or mobile ) computers like laptop, notebook, palmtop etc, contains microprocessor as a CPU and hence they come under the category of microcomputer. A microprocessor ( or computer ) understands information's composed of only 0s and 1s. It uses 2 binary numbers for it operations. A binary digit is know

Word length of microprocessor or computer A) Th e wo rd leng th of a mi cr opr oce ss or ( o r co mput er )is g ive n as n- bi t, whe re n ma y b e 8, 16 , 32 , or 6 4. B) A n 8 – bi t m ic ro pr oce sso r ( o r co mpu te r ) ca n pr oce ss 8 – b it da ta at a t ime , it s A LU i s d es igned t o pr oce ss 8 – b it d ata 's . It s ge ne ral pu rp os e r egi sters whi ch ho ld da ta for pr oce ssing are 8 – bi t r egi ste rs. C) S imi la rly a n 1 6 – bi t a nd 64 – bi t mi cr opr oce ss or ca n pr oc ess 6- 3 2 a nd 6 4 – b it of d ata a t a ti me res pe cti vel y . D) A p ro ce ssor o f lo nge r wo rd le ngt h i s m or e p owe rful and ca n pr oce ss da ta a t fast er spe ed a s co mpa red t o a pr oce ssor o f s hor ter wo rd len gth . E) T he numb er of b it s t ha t mi cr opr oce ss or ( o r co mput er ) ca n pr ocess a t a t ime is ca lle d its wo rd le ngt h. I t i s me asu re of co mput ing po we r of a co mput er. 3

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Features of 8085 

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Intel 8085 is an 8 – bit, NMOS microprocessor It is a 40 pin IC package fabricated on a single LSI chip. The Intel 8085 uses single of + 5V dc supply for its operation. Its clock speed is about 3MHz. It has 80 basic instructions and 246 0pcodes. 5

Microprocessor Architecture

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ARITHICTURE FEATURES of 8085 :1:

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It consists of three main sections. An arithmetic and logic unit (ALU ). Timing and control unit. Set of registers. AN ARITHIMETIC AND LOGIC UNIT. ( ALU ) ALU performs the following arithmetic and logical operations. 1) Addition. 2 ). Subtraction. 3 ). Logical AND. 4 ) Logical OR. 5 ). Logical exclusive.6 ). Complement. 7 ). Increment. 8 ) Decrement. 9 ).Left Shift, Rotate left, Rotate right. Clear, etc. 7

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TIMING AND CONTROL UNIT : The timing and control unit is a section of the CPU. Its generates timing and control signals which are necessary for the execution of instructions. It controls data flow between CPU and peripherals. It controls the entire operations of the microprocessor and peripherals connected to it. Thus it is seen that timing and control unit of the CPU acts as the brain of the computer system. REGISTERS : Registers are used by the microprocessor for temporary storage and manipulation of data and instructions. Data remains in the registers till they are sent to the memory or I/O devices. Intel 8085 microprocessor has the following registers, 1) One 8 – bit accumulator ( ACC ) ie. Register A. 2) Six 8 – bit general purpose registers. B,C,D,E, 8 H,& L.

8085 Pin Description

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Pin Diagram of 8085 :1:          

From this logic pin out of the 8085 microprocessor. All the signals can be classified into six groups. 1). High order address bus. 2). Multiplexed Address/data bus. 3). Power supply & frequency signals. 4). Externally initiated signals. 5). Serial I/O ports. HIGH ORDER ADDRESS BUS: The 8085 has sight signal lines, A18------A15 which are unidirectional and used as the high order address bus. MULTIPLEXED ADDRESS / DATA BUS : The signal lines AD7---------AD0 are bidirectional, they serve a dual purpose. They are used as the low order address bus as well as the data bus. 11

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CONTROL AND STATUS SIGNALS : Th is g roup o f si gna ls inclu des t wo co nt rols s igna ls ( RD & WR ), t hr ee st atus s ig na ls ( IO/ M, S 1 & S0 ) to id enti fy th e na ture of t he o pe rati on, and o ne spec ia l signa l (AL E) to i nd ic ate the be gi nni ng of t he oper ati on. POWER SUPPLY AND CLOCK FREQUENCY. VCC + 5 V Po wer supply , VSS = gr ound r efere nce , X1 ,X2 = T he se a re te rmi na ls t o be c onnec te d to an ex terna l cr ystals o sci lla tor whi ch dr ives an int ernal ci rcui tr y o f t he mi cr opr oc ess or t o pr oduc e a suit able cloc k for th e ope ra tion o f mic rop ro ce ssor . Th is s igna l ca n be us ed a s t he s ystem clo ck f or t he de vice s. SERIAL I/0 PORT : 12 Th e 808 5 ha s t wo s igna ls to i mple me nt t he s eri al

Intel 8085 Instructions

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Intel 8085 Instructions set 

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An instruction is a command given to the computer to perform a specified operation on given data. 8085 has 80 basic instructions & 246 Opcodes each instruction contain two parts, Operation code and Operand. The first part of an instruction which specifies the task to be performed by the computer is called Opcode. The second part of the instruction is the data to be operated on and it is called Operand. Example : ADD }-– Opcode, B }-– Operand. MVI }-– Opcode B}---Operand. 14

Programming of Microprocessor.

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The simplest symbolic language used for microprocessor is assembly language. The symbols are called as mnemonics. The language written in the form of mnemonics is called as assembly level language. The mnemonics are alphanumeric representation of instructions .ie. It is an combination of letters to indicate the operation of the instructions. The assembly language program for the addition of two numbers placed in two consecutive memory locations, 2501H and 2502H & the sum is stored in the memory location 2503H Mnemonics: Opcode : Operand.  LX1 H,2501H.  MOV A,M  INX H  ADD M 15  STA 2501H.

Microprocessor Applications 

Today microprocessor based systems are used in almost every sphere of life. Their applications are increasing at very fast rate day by day. These are numerous application of microprocessor. They are used in industry ,instrumentation, transportation, military equipment like tanks, radars etc. banks, business organizations, communication, automatic testing of products, lift control, speed control of motors, automatic control of generators voltage, fuel control of furnaces consumers and commercial applications etc. 16

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