Sharp MZ

I use this one. I translated all the messages into English for more commodity. It can handle sharpascii, display codes in DB and build an MZT file (same as MZF, just rename it).

Interrupt is only for AM/PM toggling. In my game, I simply disable interrupt forever, so I can enable the first DRAM area and fill it with whatever I want. You could also enable the third area as DRAM ($E000-$FFFF) because the moment you need to access VRAM or I/O are deterministic: you simply disab...

When accessing $E0-$E7, only address bus is considered, data address is dummy.

Yep, doing a OUT ($E1),A would prevent from you viewing the M command to operate.

I'm not sure why it doesn't increase. Does it mean the M command check whether your writing is effective? I wouldn't expect it but that seems the only explanation I can see for the moment.

And what @psmart advised is a very simple and good way to check since that CGROM is just plugged (so no desoldering) BUT I wonder which programmer can read it and reprogram it (supposedly using UV erasure is possible), any idea @psmart ?

The 74S157 mux are for DRAM, there is no such mux for CGROM. I just mean DRAM must be fixed to be able to go further. Obviously, it doesn't mean it will fix the CGROM issue.

So you have first issue with DRAM. Since MONITOR ROM uses system data in DRAM, chance you're not able to go further as long as that issue is not corrected.

On a stock MZ-700, $E010-$FFFF is not mapped to anything, that's why.

Checked, the Japanese version have a Japanese word printed on the key and Western version has no use for that key.

it does nothing as I suspect it was specific to Japanese version.