Re: XCHG instruction: load register AX with a 1

From: "Alison" <invalid@xxxxxxxxxx>
Date: Tue, 28 Nov 2006 22:18:11 -0000

2005 <uws2003@xxxxxxxxx> wrote in message
news:1164745288.708611.241670@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hi

In the XCHG instruction, why would be load register AX with a 1 prior
to excution of XCHG - is this
- to insure that the "Flag" variable will be set to 1 after the XCHG or
- the XCHG instruction will not work unless a 1 is loaded into AX
before executing the XCHG instruction ?

None of those.

It is to ensure that your local effective address as stored in DX doesn't
overload your carry flag.

.

References:
- XCHG instruction: load register AX with a 1
  - From: 2005

Prev by Date: Re: NewQ: Difference between an isr and a subroutine is that an isr has no arguments
Next by Date: Re: XCHG instruction: load register AX with a 1
Previous by thread: XCHG instruction: load register AX with a 1
Next by thread: Re: XCHG instruction: load register AX with a 1
Index(es):
- Date
- Thread

Relevant Pages

Re! XCHG instruction: load register AX with a 1
... In the XCHG instruction, why would be load register AX with a 1 prior ... then the flag will be correctly set to 1 ...
(comp.arch.embedded)
Re: XCHG instruction: load register AX with a 1
... In the XCHG instruction, why would be load register AX with a 1 prior ... to excution of XCHG - is this ...
(comp.arch.embedded)
XCHG instruction: load register AX with a 1
... In the XCHG instruction, why would be load register AX with a 1 prior ... to excution of XCHG - is this ... to insure that the "Flag" variable will be set to 1 after the XCHG or ...
(comp.arch.embedded)