Machine Language Guide
Basic Program
; Program name : XOR Implementation
;Programmer : Jayakanth Srinivasan
;Last Modified : Feb 18 2003
; code segment
load R1,1 ;Load register R1 with 1
load R2,0xff ;Load register R2 with 11111111
load R3,[first_number] ; move contents of location labeled
; first_number into register R3
xor R4, R3,R2 ; flip the 0's and 1's in the first number
store R4, [result]; store the result in location labeled result
halt ;halt the program.
; data segment
first_number: db 8
result: db 5
Instruction Set
Opcode Instruction Operation
2 RXY load R,XY register[R]:=XY
1 RXY load R,[XY]
3 RXY store R,[XY]
D 0RS load R,[S]
E 0RS store R,[S]
4 0RS move S,R register[S]:=register[R]
5 RST addi R,S,T register[R]:=register[S]+register[T]
integer add
6 RST addf R,S,T register[R]:=register[S]+register[T]
floating-point add
7 RST or R,S,T register[R]:=register[S] OR register[T]
8 RST and R,S,T register[R]:=register[S] AND register[T]
-
-
-
9 RST xor R,S,T register[R]:=register[S] XOR register[T]
A R0X ror R,X register[R]:=register[R] ROR X
B RXY jmpEQ R=R0,XY
0XY jmp XY
F RXY jmpLE R<=R0,X
C 000 halt halt program
The opcode is the first nibble (higher four bits of the first byte) and the three parts of the
operand are the second, third and fourth nibble.
Assembler Syntax
Label
with a digit.
Instruction
16 instructions listed in the previous section.
Comment
Numbers
๎ )
๎ )
The basic template of a machine language program is shown below.
register[R]:=memory[XY]
memory[XY]:=register[R]
register[R]:=memory[register[S]]
memory[register[S]]:=register[R]
bitwise OR
Program Header, Contains
Program Name
Programmer Name
Last Modified
Start of code segment
Start of data segment
bitwise AND
bitwise eXclusive OR
Rotate Right register R for X times
PC:=XY, if R=R0
PC:=XY
PC:=XY, if R<=R0
A label is a sequence of letters, decimal digits and special characters, but it may not start
An instruction starts with a mnemonic, followed by the operands. It has to be one of the
A comment starts after a semicolon โ;โ and ends at the end of the line. Any character is
allowed after the โ;โ.
A number can be a decimal number, a binary number or a hexadecimal number.
A decimal number is a sequence of decimal digits ('0' up to '9' . It may start with a
'-' to indicate the number is negative. It may end with a 'd' to emphasize that the
number is decimal.
A binary number is a sequence of binary digits ('0' and '1' and ending with a 'b'.
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