Legacy apps in Windows/OS X was Re: Old MS-DOS & Win Software

[Patrick Finnegan]

Chuck Guzis declared on Wednesday 07 December 2005 20:26:
> keeping things like the DAA instruction intact and supporting a bunch
> of do-nothing instructions like MOV DL,DL.

FYI, that most certainly doesn't just "do nothing."  It updates the flags 
based on the contents of the DL register, and you could do a conditional 
jump based on the results.

> Consider on Windows XP that you can still run the following code:
>
> 	mov	cl,9
> 	mov	dx,offset HWMes
> 	call	5
> 	mov	cl,0
> 	call	5

Huh?  Do you mean this?

MOV  AH, 9
MOV  DX, HWMes
INT  21h
MOV  AH, 0
INT  21h

Pat
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