On 7/18/2022 11:02 AM, Marko Mäkelä wrote: > Hi Maciej, > >> There are now two more C128s expanded to 256K of RAM using MMU >> expansion: http://www.zimmers.net/anonftp/pub/cbm/documents/projects/memory/c128/1028/index.html >> > > Great! Are spare 8722 MMU chips still reasonably easily available? Not sure I'd call them easy, but they are available and not for a ton of money, though I think they are pulls: https://www.ebay.com/itm/301700171218?epid=1281601358&hash=item463ebb45d2:g:KMoAAOSwyQtVuc1i > I am not too familiar with FPGAs, but I would expect that it should be > possible to create a FPGA based 8722 that would directly generate the > 4 CAS signals. The C128 MMU probably would even fit on a larger CPLD. It is not as complex as the other custom ICs. Though, right now, getting the IC could be iffy. > Maybe it could even be done in the DIP48 footprint, by using a > suitable SMD case, say, TSOP56. Such a daughter board would also serve > as a spare part. If someone had a GODIL, they could get the code working, and then switch to a smaller/purpose built DIP footprint. > > A step further might be to accommodate all RAM and ROM (except the > color RAM and the VDC RAM) in a daughter board, as SRAM and Flash ROM. I think this idea is best, as it appears all the memory signals are at the MMU footprint. Marko > Jim -- Jim Brain brain_at_jbrain.com www.jbrain.comReceived on 2022-07-18 20:00:02
Archive generated by hypermail 2.3.0.