Hello,
Nicolas Pomarède schrieb:
Good news, this might be useful too for other project like MIST or
similar which try to re-build a complete STF/STE with VHDL and require a
low level description of each chip.
Here are the results of my reverse-engineering work of the MMU's bank
selection logic. This is for the non-IMP/Ricoh STF MMU. Note: It was
pointed out to me that while MMU chips labeled C025912-38 were made by
Ricoh, the manufacturer of the older MMU chips C025912-20 is not known.
The -20 version is found in the very first 520STs, afaik. I don't know
if the versions -38 and -20 differ on a functional level. The IMP MMU
C100109 will probably have a much simpler circuitry for bank selection
as it doesn't support different bank sizes. However, I have yet to have
a look at this part of the IMP MMU.