Re: 8050 ROM dump

From: MikeS <>
Date: Thu, 14 Apr 2011 15:00:34 -0400
Message-ID: <60FB144A803244EBA70350F4B7540AF8@vl420mt>
Well, I dumped all 4 ROMs that I have and they match Zimmer's images


These ROMs are programmed with an active-HIGH chip select (pin20), so a 2764
(or even a 68764/6) would presumably need to have CS inverted. I think this
issue has also come up in the C64/C128 world somewhere...

If he didn't account for that then I'm surprised he read anything at all,
not just "substantially different" code ;-).


----- Original Message ----- 
From: "Jim Brain" <>
To: <>
Sent: Thursday, April 14, 2011 12:14 PM
Subject: Re: 8050 ROM dump

> On Thu, April 14, 2011 10:05 am, Steve Gray wrote:
>> This doesn't seem right. Surely commodore used EPROMs while developing
>> the
>> drives, before they made masked roms. Perhaps it's a matter of selecting
>> the correct speed EPROM? Afaik the two CPUs don't access the same rom
>> anyway. I'm sure I've seen drives with EPROMs direct from commodore.
> The user contacted me to state that he was able to rig up a way to read
> the 2364 onto his programmer.  He notes the code is substantially
> different from the Zimmers ROMs.  I don't have a copy yet, so I cannot
> verify this information (yes, it is possible he messed up the wiring on
> his reader interface, but I can't confirm either way).
> He notes he cannot continue working on it this week, but will try next
> week or so.  I will keep the group updated.
> Jim
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Received on 2011-04-14 20:00:12

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