© Thomas
Kunz 2000
SCE 574
82
Memory Reference
Ambiguities
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Consider MOV [BX],5
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Should we move a byte or a word?
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Need to instruct the assembler
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WORD PTR
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BYTE PTR
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So we get:
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MOV WORD PTR [BX], 5
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OR
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MOV BYTE PTR [BX], 5
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Consider the following example
Specify how to interpret
a memory operand, gives
type information
DS
40000
BX
2350
42350
42351
DS:BX
Low byte at low
address, high byte
at higher address
5
0
5
WORD PTR
BYTE PTR