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General Forums => The Campus => Topic started by: silentenigma on November 02, 2009, 10:18:59 PM

Title: About Operands WAIT/FWAIT
Post by: silentenigma on November 02, 2009, 10:18:59 PM
On the address:
http://www.ray.masmcode.com/tutorial/fpuchap3.htm
dear ray explains FWAIT-->"This instruction prevents the CPU from executing its next instruction if the Busy bit of the FPU's Status Word is set."

Ok i understand it. Then what about WAIT operand? Are they same or not?

On address:
http://siyobik.info/index.php?module=x86&id=324
It says:"WAIT is an alternate mnemonic for WAIT" Is that true?

if they are not same pls explain.
Best Regards
Title: Re: About Operands WAIT/FWAIT
Post by: dedndave on November 02, 2009, 11:17:51 PM
wait and fwait are the same operands
"wait" can be a little confusing if you work with CPU IC's directly, as one of the hardware lines on x86 processors is called "wait"
if you want to verify it, just assemble both and look at them with a debugger or at the assembler listing output
Title: Re: About Operands WAIT/FWAIT
Post by: FORTRANS on November 03, 2009, 02:40:28 PM
Hi,

   Yes, WAIT and FWAIT are the same instruction.  When the 8086/8087
were introduced, Other coprocessors were planned/offered.  FWAIT was
for the FPU as all floating point instructions start with "F".  Wait would be
used with a different coprocessor.

Regards,

Steve N.