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SUB  -  Subtract Instruction


The SUB instruction subtracts the second operand from the first operand.
This command has 3 parts, Instruction, then either a Register, Immediate value or a memory address.

Assembly
Sample		 Description   16 bit Machine
  Code
SUB AL, 0x03;  8 bit immediate from AL  2C 03
SUB AX, 0x0303;  16 bit immediate from AX  2D 03 03
SUB CL, 0x03;  8 bit immediate from an 8 bit Register   80 E9 03
SUB CX, 0x03;  8 bit immediate from 16 bit Register   83 E9 03
SUB CX, 0x0303;  16 bit immediate from a Register   81 E9 03 03
SUB CL, AL;  8 bit Register from 8 bit Register  2A C8
SUB CX, AX;  16 bit Register from 16 bit Register  2B C8
SUB [BX], 0x03;  8 bit immediate from memory address   83 2F 03
SUB [BX], 0x0303;  16 bit immediate from memory address   81 E9 03 03
SUB [BX+2], 0x0033;  16 bit Immediate from memory address  81 6F 02 23 00
SUB AX, [BX];  Memory address from 16 bit Register  2B 07
SUB [BX], AX;  16 bit Register from memory address  29 07
SUB AX, [BX+2];  16 bit Register from memory address  2B 47 02
SUB [BX+2], AX;  16 bit Register from memory address  29 47 02