Page 218 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Unit 11: Programming Process

(a) Our computer has 4 registers and 32 memory locations. Notes
(b) Each instruction is 16 bits.
(c) Here is a machine language program for our simulated computer:
1000000100100101
1000000101000101
1010000100000110
1000001000000110
1111111111111111

Instruction ID Register # Memory
Location

LOAD contents of memory 100000010 RR MMMMM
location into register example:
R0 = Mem[3]
100000010 00 00011
LOAD contents of memory location into 100000010 RR MMMMM
register ex: R0 = Mem [3]
100000010 00 00011
Store contents of register into memory 100000010 RR MMMMM
location ex: Mem[4] = R0
100000100 00 00100
MOVE contents of one register into 100100010000 RR RR
another register ex: R0 = R1
100100010000 00 01
ADD contents of 2 registers, 1010000100 RR RR RR
store result in third. ex: R0 = R1 + R2
1010000100 00 01 10
SUBTRACT contents of 2 1010001000 RR RR RR
registers, store result into third ex: R0 = R1 — R2
1010001000 00 01 10
Halt the program 1111111111111111

11.2.2 Reading Machine Language
(a) In our case, first nine bits specifies the operation, last 6 (or 7) bits specifies the arguments:
100000010 01 00101 Load Memory 5 — > R1
100000010 10 00101 Load Memory 5 — > R2
1010000100 00 01 10 R1 + R2 — > R0
1111111111111111 Store R0 — > Memory 6
(b) It is very tedious to program in machine language.

LOVELY PROFESSIONAL UNIVERSITY 211