Re: Commented 1541-II DOS disassembly

From: smf <smf_at_null.net>
Date: Sat, 25 Aug 2018 22:07:13 +0100
Message-ID: <e8c4290e-78cf-2389-f854-78aaeafda539@null.net>
On 25/08/2018 20:47, Spiro Trikaliotis wrote:
> 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.

Again, if you think he's unsure then I think you've misread the article.:

> I am referring to statements like the following:
>
>     "A possible SAVE@ related bug is in the serial bus communication
>     routines. [...]

Right, it's a theory by someone else that hasn't been verified and 
contains errors. It looks like it could cause problems to other 
operations other than save@ & I'm not sure if it's possible to trigger 
that with the standard basic command. By fixing the bug and disabling 
ATN when it's supposed to be disabled then it can't cause any issues.

My main intention of posting this wasn't so that you could criticise how 
sure he is of his work, but give an explanation of why the changes were 
made.

The article is clear why the changes were made.

> 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.

Right the 02 rom is the first with the save@ bug fix according to the release notes from commodore. They list some other bug fixes as well.

http://www.zimmers.net/anonftp/pub/cbm/firmware/drives/new/1541/1541C.251968-02.txt 
Received on 2018-08-26 00:00:05

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