Re: Commented 1541-II DOS disassembly

From: Spiro Trikaliotis <ml-cbmhackers_at_trikaliotis.net>
Date: Sat, 25 Aug 2018 21:47:11 +0200
Message-ID: <20180825194711.prvfttakv4bvk4h2@hermes.local.trikaliotis.net>
Hello,

* On Sat, Aug 25, 2018 at 06:52:54PM +0100 smf wrote:
> 
> On 25/08/2018 12:52, Spiro Trikaliotis wrote:
> > For the article, cf.
> > http://csbruce.com/cbm/transactor/pdfs/trans_v7_i02.pdf, page 37-39 in
> > the PDF, or 33-35 as written on the page.
> > 
> > Interestingly, it seems Philip A. Slaymaker fixed the problem, but he
> > does not know for sure which of the patches fixes it, or if it is all of
> > them.
> > 
> > Or do I misunderstand that article?
> If you think he does not know, then I think you misunderstood the article.

I am referring to statements like the following:

   "A possible SAVE@ related bug is in the serial bus communication
   routines. [...]

   Gerry Neufeld's theory of a serial bus ATN related SAVE@ bug is
   presented in [...] If a new command is sent before SAVE@ is
   completed, the BAM or directory may not be updated correctly [...] I
   have not tested his theory either, [...]"

So, we have a bug which might affect SAVE@, or it might not. Nobody
knows, not even the author.

This looks to me as if he is not completely sure about the nature of
SAVE@. He knows he has fixed it, but he does not know for sure which
patches all belong to the fix.


Having said this: If using absolute LDA $00FF,X instead of ZP LDA $FF,X
is part of the fix, then 251968-01 does not include that fix yet.
Thus, 251968-02 is the first ROM on the 1541 that includes this. All
1570 and the 1571-03 ROM (which is the first 1571 ROM known to me)
include that fix, too.

Regards,
Spiro.

-- 
Spiro R. Trikaliotis
http://www.trikaliotis.net/
Received on 2018-08-25 22:00:04

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