After considering at how 74LS283 works, I do see that SW3 with 128 K EEPROM is not effectively used. Right now there are two 64 kB banks, each of them can be addressed at 0000, 4000, 8000 or C000. This is only 8 combinations of A14, A15 and MA14, MA15, MA16 switches out of available 16.
It is possible to use 256 k or 512 k EEPROM. By the way - it is a lot easier and cheaper to buy SST 39SF040 (512 k) - other IC's (010 and 020) are backordered indefinitely. Let me know what you think. 8 and 32K games work fine, I am experimenting with larger games.
Let me know if I am wrong. Thanks

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First of all, thank you so much sharing! really appreciated.

I ordered 64KB ROM PCB, and prepared SST 39SF010A (1MB Flash)..

And I programmed 32K rom by TL866 programmer (all default), and programming itself was successful..

But MSX can not run the 32K rom..

Any advice for me to investigate further?

Any MSX program to flash rom file?

Best,
Kim.

Edit: Nevermind, it seems I've ordered an old revision with 27C512 back then … but still interested to learn ;)

I've already ordered your 64KB cartridge PCBs, but seeing other cartridge PCBs made me suspicious.

1. They require setting jumpers in order to use a 512Kbit ROM because of memory mapping, and other jumpers to use smaller ROMs because of different pinouts. Your layout even suggests a SST39SF010 and stays completely jumperless. How does memory mapping work?

Additionally, I've still got smaller EPROMs available. You wrote that ROMs with less than 64K are ok. Questions regarding replacing the SST39SF010, since pinouts are incompatible:

2. Is it correct that disconnecting pin #30 NC (≙ #28 Vcc on a DIP28 footprint) from the circuit and connecting it to Vcc instead (making it a supply pin) simply allows using a 27C512, if aligned to the right?
3. Going further, connecting #3 A15 (≙ #1 Vpp on DIP28) to GND and #29 A14 (≙ #27 /PGM on DIP28) to Vcc instead would allow to fit a 27C256? But would it work in MSX memory mapping context?

From readme.md:

It will fit any ROM dump <64kb.

I guess this should either be 64 KB (KByte) or 512 Kb (Kbit) – right? Sorry for asking, in ROM context both makes sense.

Hi, How many ROM images can I put on 128 k flash?
Can I put, say four of 32 k ROMS?