From: Nicolas Welte (welte_at_chemie.uni-konstanz.de)
Date: 2002-04-16 14:08:00
email@example.com wrote: > FYI, I face the same problem. But I have the advantage of a second working > PET :) The same here :-) I'm going to make a replacement RAM/ROM card that plugs into the 6502 socket of the original PET, and then all the ROMs and RAMs can be put in a safe place. As a nice side effect, it will offer the full 32kB RAM, maybe switchable to 4k, 8k and 16k configurations, as well as switchable ROM versions. This shouldn't need more than a 32kB SRAM chip and a 32kB EPROM chip plus some glue logic. Is there any use for an option ROM socket for a combined 16 or 32kB option EPROM? When I have the PCB layout ready and tested, it will be uploaded somewhere, of course. One problem that remains is the video circuit, it also uses a ROM and two RAMs that are not replaced by this board. I got a schematic (reverse engineered by Paul Förster) of a very simple 6550 replacement board that uses only one 2114 and one 4000 series gate chip (combined NAND, OR, NOR) that could be used to replace the video RAM, and for the character ROM, either make an adaptor socket for a 2716 or bigger, or hope it will last for a while. This should keep our PETs running safely for this decade or longer :-) Nicolas Message was sent through the cbm-hackers mailing list
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