I don't know this machine, but reading the comments... Can't you just cut the pin 22 of original ROM and ground it? Do you really have to replace the whole chip?
what differences are there between a and b it is necessary to have to activate the rtc with graft key I say it by carnivore2, and read that the real time clock is necessary in msx2 and +
what differences are there between a and b it is necessary to have to activate the rtc with graft key I say it by carnivore2, and read that the real time clock is necessary in msx2 and +
So after reading the whole thread, the difference between a and b version supplied by gdx is really just a reset option for the sram. In MSX2 and higher you can save some screen settings, boot text and the time in the sram which is powered in the FS-A1mk2 by two AA batteries. A reset of the SRAM can be helpful if someone saved the screen at width 3 with strange colors. Same can be however be achieved by removing the batteries for a short time.
Usually when I do this for people I upgrade the computer to MSX2+ too, because it's so simple to replace the VDP since you are already rewriting the main ROM. I have a specially modified MSX2+ ROM which always display boot logo (no need for F4 port). If the computer is a model that has kanji font (A1F) it works even better because then call kanji works, too.
I usually put basic kun compiler at the place of the firmware so it ends similar to a Sanyo 2+ when it's the A1F...
