This thread has a schematic http://www.lemon64.com/forum/viewtopic.php?t=56301&postdays=0&postorder=asc&start=15 It looks like he did alot of testing and had to change a few things each time he hit a problem. On 21/02/2017 15:11, Gerrit Heitsch wrote: > On 02/21/2017 09:12 AM, Francesco Messineo wrote: >> On Tue, Feb 21, 2017 at 8:32 AM, Baltissen, GJPAA (Ruud) >> <ruud.baltissen@apg.nl> wrote: >>> Hallo Gerrit, >>> >>> >>>> When I did my experiments with SRAM to replace the DRAM in a C64 it >>>> was never really stable until I added the OR gate to the circuit. >>> >>> Have you documented this anywhere, including schematics? >> >> I have not tried it, but I assume it should be easy: >> >> 74LS373 (or 573) latching the 8 row address lines from original DRAM >> to the first 8 address lines of SRAM chip, /OE tied low, LE driven >> directly by /RAS. Direct connection between the 8 original DRAM >> address lines to the other 8 address lines of the SRAM (old column >> address). /CE of the SRAM = /RAS OR /CAS. R/W signal should go >> directly. >> Correct me if I'm missing something. > > No, that's the circuit I used. I used a '573 since that one has a > better pinout, you can place the Latch and the RAM side by side and > save having to wire 8 lines. Also, I didn't observe the address line > numbering on the RAM (A0 to A0, A1 to A1...). It's a static RAM, so > you can connect the address lines in any order you like. Same for the > data lines. > > The idea for the circuit came from the way the address signals for > char-ROM and color-RAM are generated in the C64. > > Gerrit > > > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2017-02-21 21:00:01
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