Posted By
candle
on 2019-06-18
15:49:00
|  Re: Possible 8501 replacement kit?
16MB REU is in form of Ultimate 1541 or/and Cameleon cartridges
they contain FPGA chips with implemented SDRAM controller plus 16mbytes of SDRAM
6502plus4 contains small CPLD chip far inferior to what is used in these mentioned before, and, in such limited space chances for that are slim, i would need to resort to 0.5mm pitch BGA packages both for RAM and rest of the logic, power supply would require more components too, as FPGA chips are using at least 2 (more commonly 3) voltage rails for power, the board itself would have to be at least 4, possibly 6 layers of copper just to get escape routing done of such FPGA
this suppose to be as cheap as possible, but i don't know what the final price could be
next thing for plus4 i'm going to do is pla/rom replacement, possibly with SID in one form or another (i've made some work with FPGA SID implementations years ago, with SoundBoard project for Atari)
anyways, FPGA chips can be inexpensive and fairly simple to use, don't get scared, but if you need it to be small and cheap it will be either one or another, not both
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