RE: FLASH ROM incompatibilities with C128

The 6502 architecture can suffer in one area in particular with faster
parts on read cycles and that is at the end of the cycle; Fast parts
sometimes are faster to release data and let it go invalid.  The '02
family can require 5-10 ns of hold time which might as well be forever if
you don't have it.

-----Original Message-----
From: owner-cbm-hackers@musoftware.de
[mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Jim Brain
Sent: Tuesday, December 04, 2012 9:18 PM
To: cbm-hackers@musoftware.de
Subject: Re: FLASH ROM incompatibilities with C128

On 12/4/2012 8:12 PM, Julian Perry wrote:
> Hello Jim,
>
> Wednesday, December 5, 2012, 1:06:45 PM, you wrote:
>
>> On 12/4/2012 5:19 PM, silverdr@wfmh.org.pl wrote:
>>> On 2012-12-04, at 19:34, Jim Brain wrote:
>>>
>>>> Since I don't have one of the affected units, I can't provide much
more detail, though if there is interest in understanding this further, I
could see about getting a customer to swap out their unit for one in my
stock so I can probe it.
>>> It might be useful to know what it is about (you say 128 only and only
flat and only some of them? Or all of them but not always?
>> Only flat 128s
>> Only a few (3-6 of them in the 3 years I have offered JD) Never any
>> other unit types.
> I had the incompatibility problem you mention (from a JiffyDOS rom,
> which you kindly and promptly replaced with an EPROM :) ) - and my
> machine was a plastic-cased Commodore 128D (not DCR)
Ah, I stand corrected.  The plastic C128D uses a flat 128 mobo, as I
recall.

Jim

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