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Posted By
SukkoPera
on 2025-06-19
03:36:41
|  Re: J-CPU264
I've said it multiple times: don't buy these 100% FPGA recreations, prefer those that use a real 6502 CPU and just recreate the extra 6510/8501/8502 bits.
Reason: any recreation necessarily implies a lot of guesswork (unless you have very detailed documentation, which is rarely the case). The more the guesswork, the more potential for subtle bugs and incompatibilities. This is particularly important for non-open-source stuff, which might never see any updates even if bugs are found (if it's open, anyone can fix it at any time, if it's not, you have to wait for the author, who might no longer be interested).
Personally I now recommend Daniel Mantione's replacement, it's open source, cheaper and works very well, no known bugs at the moment.
Be careful with the 6502plus4: it seems to work fine as a CPU replacement but the Hannes expansion it implements has bugs. |
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Posted By
bszggg
on 2025-06-19
08:25:18
| Re: J-CPU264
@SukkoPera How comes up the hannes problem? And is it on the 256k too, or just the 512? |
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Posted By
SukkoPera
on 2025-06-19
10:21:30
| Re: J-CPU264
It's difficult to explain, it's like bank switches only take effect after "some time". The latest version of @siz's RAM tester can expose this behaviour.
I don't think it can be restricted to 256 kB, it's always 512 kB. Or you can skip the memory expansion feature altogether.
Anyway it's OT, we can open a dedicated topic if necessary. |
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