Re: Second Opinion on unknown PET option roms

From: Hans Liss <Hans_at_Liss.pp.se>
Date: Mon, 6 Sep 2021 22:35:02 +0200
Message-ID: <8e8102cf-c7a5-a7ec-655e-70c32d087a15_at_Liss.pp.se>
I used the VICE monitor to load that block into PET video RAM:

diagnostic 320350g

a8-a11 bad

tv ram ok

i-ram bad

z-page ok

a8-adr bad

stack ok

remove clip

/Hans

On 2021-09-06 22:14, Hans Liss wrote:
>
> 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 23:03:41

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