FLASH ROM incompatibilities with C128

From: Jim Brain <brain_at_jbrain.com>
Date: Tue, 04 Dec 2012 12:34:02 -0600
Message-ID: <50BE421A.8000104@jbrain.com>
Over the time I have been putting JiffyDOS on FLASH ROMs with adapters 
to fit in 2364/231228 sockets, I have found a handful of users who 
experience issues with the FLASH ROM option on C128 machines.  I replace 
them with normal EPROM-based versions, and the problem disappears.  It 
only happens on flat C128s, and rarely.

I am using Atmel AT49F001 with 55ns or 70ns speeds, which should be 
considerably faster than the original ROMs, and are faster than the 
EPROMs I use to replace the problem ones.

It's not an issue, per se, as I can address it by swapping out FLASH for 
EPROM, but I thought the group might be interested in the fact that it 

Since the adapter is simplistic and passive, and I did use a ground 
plane and proper high frequency routing rules when creating the PCB, I 
doubt it is the PCB.  THe pins and traces as gold, so contact should not 
be an issue.  Thus, I think it is the FLASH, but not sure if it's speed, 
drive capacity, or something else.  As I've had other things of higher 
priority, and swapping them with EPROM always fixes the issue, I have 
not pursued any research on the issue.

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.


Jim Brain

       Message was sent through the cbm-hackers mailing list
Received on 2012-12-04 19:00:12

Archive generated by hypermail 2.2.0.