Solution: MPI

Ques_1 (Any Three) (6)

(1) What do you mean by low level and high level programming languages?

Programming languages that are machine dependent are called low level

languages. For

example, assembly language(8085/8086/8051) is a low level language.

On the other hand, programming languages that are machine independent are

called high level languages. Examples are BASIC, FORTRAN, C, ALGOL, COBOL, etc.

(2) The address capability of 8085 is 64 KB. Explain.

Microprocessor 8085 communicates via its address bus of 2-bytes width the

lower byte AD0 AD7 and upper byte A8 A15. Thus it can address a maximum of 216

different address locations. Again each address (memory location) can hold 1 byte of

data/instruction. Hence the maximum address capability of 8085 is

= 216 1 Byte

= 65, 536 1 Byte

= 64 KB (where 1 K = 1024 bytes)

(3) Mention the addressing modes of 8085. What jobs ALU of 8085 can perform?

Each instruction indicates an operation to be performed on certain data. There are

various methods to specify the data for the instructions, known as addressing modes.

For 8085 microprocessor, there are five addressing modes. These are:

Direct addressing

Register addressing

Register indirect addressing

Immediate addressing

Implicit addressing.

The Arithmetic Logic Unit (ALU) of 8085 can perform the following jobs:

8-bit binary addition with or without carry.

16-bit binary addition.

2-digit BCD addition.

8-bit binary subtraction with or without borrow.

8-bit logical OR, AND, EXOR, complement (NOT function).

1-bit shift operation.

(4) What are the temporary registers of 8085? Describe the utilization of temporary

register in 8085 operations.

The temporary registers of 8085 are temporary data register and W and Z

registers. These registers are not available to the programmer, but 8085 uses them

internally to hold temporary data during execution of some instructions.

CALL-RET instructions are used in subroutine operations. On getting a CALL in

the main program, the current program counter content is pushed into the stack and

loads the PC with the first memory location of the subroutine. The address of the first

memory location of the subroutine is temporarily stored in W and Z registers.

Again, XCHG instruction exchanges the contents H and L with D and E

respectively.W and Z registers are used for temporary storage of such data.

(5) Describe the general purpose registers of 8085? Mention the utility of the general

purpose registers. In what other way HL pair can be used?

The general purpose registers of 8085 are: B, C, D, E, H and L. They are all 8-bit

registers but can also be used as 16-bit register pairsBC, DE and HL.

General purpose registers store temporary data during program execution, which

can also be stored in different accessible memory locations. But storing temporary data

in memory requires bus accesshence more time is needed to store. Thus it is always

advisable to store data in general purpose registers.

The more the number of general purpose registers, the more is flexibility in

programmingso a microprocessor having more such registers is always advantageous.

HL register pair can be used as a memory address pointer.

Que_2 Draw the timing diagram for execution of instruction MVI A, 32 H. (4)

or

Draw the Timing diagram for Read Cycle and Write cycle for byte operation. [4]

Read Cycle

Write Cycle

Que_3 Write the algorithm and make flow chart for multiplication of two 8-bit numbers with

program instructions using assembly language of 8085.

Algorithm:

Step 1: Start the microprocessor

Step 2: Get the 1st 8 bit numbers

Step 3: Move the 1st 8it number to register B Step 4: Get the 2nd 8 bit number

Step 5: Move the 2nd 8 bit number to register C Step 6: Initialize the accumulator as zero

Step 7: Initialize the carry as zero

Step 8: Add both register B value as accumulator Step 9: Jump on if no carry

Step 10: Increment carry by 1 if there is

Step 11: Decrement the 2nd value and repeat from step 8, till the 2nd value becomes zero.

Step 12: Store the multiplied value in accumulator

Step 13: Move the carry value to accumulator

Step 14: Store the carry value in accumulator

Flow Chart

Code:

LXI H 4500h

MOV A M

INX H

MOV B M

MVI D 00h

MOV C A

MOV A D

GO: ADD B

JNC AHEAD

INR D

AHEAD: DCR C

JNZ GO

STA 4100h

MOV A D

STA 4101h

HLT