[A83] Re: delay code

To: assembly-83@lists.ticalc.org
Subject: [A83] Re: delay code
From: Rob van Wijk <robvanwijk@gmx.net>
Date: Wed, 27 Mar 2002 10:20:53 +0100 (MET)
References: <000601c1d4f8$d6ce8080$d905040a@tijl>
Reply-To: assembly-83@lists.ticalc.org


> 
> > Is it that significant when only nop's are executed with halt?
> > Then only the I register gets updated, am I right?
> 
> A HALT waits for an interrupt. While waiting, it switches the Z80 into low
> power mode. Then when an interrupt is accepted, the interrupt routine is
> executed, which on its turn, returns to the code following the HALT
> instruction.
> 
> On itself, HALT doesn't affect any registers.

HALT _does_ increase the R (memory refresh) register.

Rob van Wijk

> 
> As for the I register, it is never changed except with LD I,A or when the
> Z80 is reset.
> 
> 

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References:

[A83] Re: delay code

From: "Tijl Coosemans" <tijl@ulyssis.org>