Hallo Mia, > I could send you the files if you are interested. Thank you for the offer but I did about 50% already. > ... be a good idea to include 1MB directly on the motherboard. That is my intention anyway. But first things first like: - the schematics of both the 610 and 720, busy with that. - the devices/symbols/packages of the boards, busy with that And I think this is a one man's job because I have no idea how split up this job and to combine the results. Note: I use Eagle 7.7 so if you want to do it in Kicad, please do. - to find out what the various ICs do I have no intention to recreate the original board because I don't see any gain in doing that. As said before, I want a new version with 1 MB of RAM and, preferably, the 8088/8087 on the same board. To make things simpler I would prefer to use SRAM; no CAS/RAS issues which simplifies the timing i.e. less hardware IMHO. BUT IF WE HAVE NO IDEA WHAT THE ORIGINAL LOGIC DOES..... So if you, Steve or anybody wants to help, please find out what all the logic does. READ: mainly all those bloody 74ls74 latches :) Just popped up when writing the above: when using a 1 MB DRAM SIM we could save a lot of space. The extra refresh bits are no problem IMHO. Just in case the SRAM idea doesn't work out well. - what ICs are we going to use? The one trouble shooter that comes into my mind is the 6525. Replacing the glue logic with a CPLD does save space but can it be used to replace the 6525s as well? Very very wild shot: replacing them with better available ICs like the 6522, 6526 or maybe even the 8255? Enfin, enough things to do and to wonder about. But what else should we being the marvelous CBM-Hackers? :) FYI: I think I just finished the minimum 720 board. It contains: - 6 holes to fix it to the frame. The holes are surrounded by circles of top and bottom layer. The original inners are metalized but I have no idea how to do that: the available VIAs are too small. - keyboard connector - RS232 connector - IEEE edge connector - cassette port edge connector - external sound connector - cartridge connector - 4 holes for the metal cover. I could have used VIAs (I think) but they coverd the drilling holes and the rim had the wrong size. Any ideas are welcome! The rest, like the power connector and the expansion connectors, don't have to be fixed at exactly the same place so I left them out. There will come sparate devices for them. -- Kind regards / Met vriendelijke groet, Ruud Baltissen www.Baltissen.orgReceived on 2018-04-27 13:00:02
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