On 4/13/18 5:21 PM, Michał Pleban wrote: > That looks intresting! But judging from the photo and the components on > the board, it reproduces Mia's idea of hooking both to the 6509 > expansion port aand 8088 memory port in order to replicate the > multiplexers on the mainboard. A good side is that it doesn't require > replacing the PLA or sticking anything into the RAM sockets on the > mainboard. A downside is that it requires lots of additional compoments > to replicate those already on the mainboard. Even with the extra chips, the B1024 board fits in the low profile case. If the goal is to have a solderless expansion, this may be a good approach because the RAM on the mainboard is not always socketed. I know this from first-hand experience. My own machine did not have sockets originally. You can see a photo of it here: http://mikenaberezny.com/hardware/cbm-ii/b128-256k-upgrade/ There is no surviving schematic or documentation for the B1024 board but advertisements said it could simply be plugged in. There was no mention of needing to remove the RAM from the mainboard. I tried it briefly with the RAM still on the mainboard and the machine seemed to work fine. I then installed sockets and now I don't have any RAM on the mainboard. Regards, Mike -- Mike Naberezny (mike@naberezny.com) http://6502.orgReceived on 2018-04-14 04:00:42
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