Date   : Fri, 17 Mar 2006 14:56:52 +0000
From   : Andy Armstrong <andy@...>
Subject: Re: 1MHZ SCSI/ATA board

On 17 Mar 2006, at 14:35, John Kortink wrote:
> You don't save X. Costs four more. But : save X instead
> of Y and use LDX #0, LDA (txptr,X) and an extra TSX at
> prstr3. Saves three.

Good, good - I hoped you'd bite :)

> Also, it seems a waste to save and restore zero page
> locations. Better assign a few for free use (as long
> as intervening JSRs and interrupt routines stay away
> from them), e.g. three of them (save and restore at
> a higher level if need be, e.g. across service call
> handling, if in a ROM), then (this is my own library
> function for inline printing, well sort of, I also
> corrupt A in practice, not using 'free') :

Yeah - the zp save is so I can call that code from anywhere because I  
use it for debug output.

-- 
Andy Armstrong, hexten.net