Re: Second Opinion on unknown PET option roms

From: Hans Liss <Hans_at_Liss.pp.se>
Date: Mon, 6 Sep 2021 22:14:43 +0200
Message-ID: <af09a62f-212a-cfc9-a264-d3f57c2c2fbf_at_Liss.pp.se>
901447-30_2001diag_0000.bin seems to disassemble nicely at $9800, and 
http://mhv.bplaced.net/cbmroms/cbmroms.php lists "901447-30" as a 
"Diagnostic Clip" for PET 2001, to be located at 9800-9FFF. 
Incidentally, the code around $9979 seems to load bytes from $99ce to 
$99d8 to screen memory, so maybe someone more patient than I can figure 
out what it says? I suspect the entire block between $9985 and $99d8 is 
screen text, actually.

901484-03-2031ro_c000.bin seems to match "901484-03" on the same page, 
which describes it as DOS 2.6 Low for the 2031 drive, to load at c000. 
There's a copy of that ROM on 
http://www.zimmers.net/anonftp/pub/cbm/firmware/drives/old/2031/index.html, 
however, which seems to have nothing in common with this one. So that's 
strange.

/Hans

On 2021-09-06 21:39, Hans Liss wrote:
>
> Better link: 
> http://www.zimmers.net/anonftp/pub/cbm/firmware/misc/unknown/
>
> The low count of "a9" bytes in several of these is a sure sign it's 
> not 6502 code. I took a quick look at a few:
>
>   * 8in-cpm-trbdos.bin is definitely Z80 code (or 8085, perhaps?). A
>     CPM "driver" for 8-inch floppies, perhaps?
>   * 740turbo1-1.bin is also Z80 code.
>   * I suspect ultima-ii-v1-73.bin is also Z80 code.
>   * create-new-base.bin and 40-80-60h.bin seem to be something else,
>     like not program code at all.
>
> I found a fairly useful disassembler at 
> https://onlinedisassembler.com/odaweb/, by the way. I tend to use 
> wfdis for 6502 code, but this one has many other architectures and 
> accepts small hex dumps as input.
>
> /Hans
>
> On 2021-09-06 19:23, Bo Zimmerman wrote:
>> Hello all,
>>
>> Dave McMurtrie contributed a nice pile of PET option rom images to 
>> the funet/zimmers archive _at_ 
>> http://www.zimmers.net/.../computers/pet/other/index.html
>>
>> I had no trouble identifying and classifying most of them. However, 
>> there were several that I could either not get working, properly 
>> disassembled,, or just couldn't identify.  This is fairly new to me, 
>> so I created a special place for them here:
>> http://www.zimmers.net/ano.../pub/cbm/firmware/misc/unknown/
>>
>> If anyone out there enjoys digital archeology, I'd ask you to give a 
>> second or third opinion on some of those unknown roms. It's possible 
>> the eproms were just corrupt or unreadable, but I'd sure like someone 
>> else to concur before I throw any of the images out.
>>
>> - Bo Zimmerman
>>
>>
Received on 2021-09-06 23:00:04

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