On 2012-11-24, at 12:49, Gerrit Heitsch wrote: > Ok... Looking at your new circuit, using A14 instead of _BASIC on IC1B should work, it's LOW when BASIC is active and HIGH when KERNAL or CHAR is active. Behaves the same as the old _BASIC signal. > > The generation for _CS and _OE for the EPROM is also OK. > > Now the only signal left over to take of is A14 of the EPROM. This one must only go LOW when _KERNAL is LOW and A14 is HIGH. Means you need 2 Inverters. One for _KERNAL and one for the output of the AND gate. > > Sounds like you need at least 2 Transistors + 4 resistors or you need to add a 74LS04 or you need to rearrange the EPROM contents. I'd go this way as long as it can work for wide board without extra parts too. > Currently, I see no other way to do it. At least I feel better that I am not the only one who missed something obvious ;-) > Anyway I try, I need extra logic that I can't build by what the 74LS00 and 74LS08/11 supply. Yup - same here. I am now trying with swapped parts: http://dl.dropbox.com/u/58002657/cbm/c64/epromel_memmap0.png -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-11-24 13:00:04
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