On 2012-10-18, at 18:52, Gerrit Heitsch wrote: >> Why stop there? Replace the TTL with micro-sized versions, mount them inbetween the pin header on the bottom, and make the board the same size as the eprom! >> Just kidding! ;-) > > No, the next step would be to design one such circuit for a 250469 board, the one where the BASIC and KERNAL are in one ROM and only the char-ROM is extra. > > Should be a bit easier since _KERNAL and _BASIC are already added together by an AND gate on the board. Ironically this seems to do more harm than good for the glue ;-) > That way one doesn't need a 74LS11, a 74LS08 should do. I save one input on the _OE/_CE gate but then have to handle three states instead of two to distinguish between BASIC and KERNAL.. which so far seems to me like I can't make it with the same EPROM content layout and chip count I had before. With shifted content I came up with something like (still have to double-check for correctness): http://dl.dropbox.com/u/58002657/cbm/c64/rom_adapter_narrow0.png Can you have a look? Maybe you have some better ideas, especially ones that would allow to keep the old EPROM content layout? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-11-24 08:00:05
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