Convert an 8-4164 DRAM based Commodore to utilize 2 4464 DRAMs or an SRAM replacement system
Contrary to first glance, C64 motherboard models 250407 and 250425 do NOT share the same 8 DRAM IC layout. It's close, but just slightly off. Therefore, there are two versions of this carrier design, one for each motherboard.
There's no logic on the PCB, it just passively maps the 8 individual IO signals from each DRAM socket to one of the 2 4464 DRAM footprints. Care has been taken to preserve the relative order, so D0 on the 4164 and D0 on the 4464 should be the same.
I designed this board to allow use of the new 2 Megabyte SRAM replacement 9which natively fits in 2 DRAM-IC motherboards, without having to create a brand new design. This design is also useful to simply replace the 8 original 4164s with 2 4464 ICs, or a simple 64kB SRAM RAM replacement
I am considering creating a run of these designs. Let me know if there is interest.
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