87C750 Assembly Language Intro

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87C750 Assembly Language Intro
ECET2210/01
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Categories of Instruction Mnemonics

• Arithmetic
• ADD - addition
• ADDC - addition with carry
• SUBB - subtraction
• INC - increment
• DEC - decrement
• MUL - multiplication
• DIV - division

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• Logical
• ANL - AND 2 bits
• ORL - OR 2 bits
• CPL - complement/invert
• XRL - XOR 2 bits
• RL - rotate bits right once
• RLC - rotate bits right thru carry bit
• RR - rotate bits right once
• RRC - rotate bits right thru carry bit

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• Program Control
• CALL - subroutine call
• SJMP - short jump
• AJMP - absolute jump
• LJMP - long jump (N/A on 75x)
• RET - return from subroutine
• RETI - return from interrupt

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• Data Transfer
• MOV - move RAM contents
• MOVX - Move external - N/A on 75x PUSH - push
  to stack
• POP - pop from stack
• XCH - exchange

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87C750 Addressing Modes
Direct Addressing - operand is an 8-bit address
(only for RAM and SFRs) MOV A, 40h BBh -gt
A MOV B, P1 2Fh -gt B
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Indirect Addressing - address contained in any
one of R0, R1, SP (all 8 bits) and DPTR (16
bit) MOV A, _at_R0 AAh -gt A
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Immediate Constant Addressing - operand is data
value MOV A, 42h 42h -gt A MOV B, 42
2Ah -gt B
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Register Addressing Mode - contents of registers
are accessed with instructions having a 3-bit
specification MOV A, R1 22h -gt A
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Indexed Addressing - address formed by adding
contents of A to DPTR (data pointer) or PC (used
for program mem.) MOVC A, _at_A DPTR
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DEBUG assembler directives MOD750 required
for all programs org 00h MOV DPTR, 0100h init.
l.u. table MOV A, 0 A number MOVC A,
_at_ADPTR A pattern org 0100h here is where
l.u. table starts DB 0CH,0F9H,0A4H,0B0H,99H,92H,82
H DB 0F8H,80H,90H,88H,83H,0C6H,0A1H, DB 86H,8EH
here is lu table END a must at the bottom of
code
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THIS IS VERY RARELY USED Register Specific Mode
- contents of certain registers are accessed with
instructions instead of direct bytes MOV A,
100 100 -gt A MOV ACC, 100 100 -gt A