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Q34375: Documentation Error on the LGDT Instruction |
/pubs/pc/reference/microsoft/kb/Q34375/ |
Article: Q34375
Version(s): 5.10 | 5.10
Operating System: MS-DOS | OS/2
Flags: ENDUSER | docerr
Last Modified: 12-JAN-1989
The "Microsoft Macro Assembler 5.10 Reference Guide" states that
the LGDT instruction only takes a memory 64 operand while the Intel
manual states the LGDT instruction takes a memory 48 operand.
The MASM Reference is incorrect. The correct operand size is memory
48. These instructions load essentially a 2-field structure whose
total size is 48 bits. The first two bytes are the limit field and the
last four bytes are the base field. This can be defined using the DF
directive, or by defining a structure as described.