On 2012-09-17, at 19:50, Jim Brain wrote: >> The NAND version looks like this: >> >> https://dl.dropbox.com/u/58002657/rom_replacement_nand.png >> >> It has four pull-up resistors. One would of course be better. So you mean you used 148 in place of LS11 and 257 for the second one (interchangeable with 00), right? > Yes, I hooked the BASIC/KERNAL/CHARROM to the 148, and the GS output feeds the CE/OE line of the EPROM. > > A12 is then handled as Gerrit and you have previously described. > > BUt, what does JP301 do in the schematic? I don't think I accounted for it, and I have just glanced at your schematic. As Gerrit already explained - it is there to select another 8K segment of the 27C256 for a second KERNAL. One BASIC, two KERNALs and two CHAROMs just fill up a 27C256 nicely. > I can draw it up again (the 257/148 option was easy to wire, nothing special to lay out), as I just drew enough of it in EAGLE last night to prove to myself it was doable. I believe I can figure it out myself without too much effort but if you feel like doing this then yes, please. I could then quickly check routing area requirements for both options. -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-09-17 19:01:24
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