Just bought the Yamaha for upgrading it to MSX2+, but decided not to go all the way, because I already have the similar 2+ in my collection. I also have the untouched MSX2. Finally I decided to patch the BIOS and leave the old VDP. What was done:
- changed the default font (it is now like in MSX2+, much better looking - see the image below)
- changed the keyboard layout so that the numbers are input without a Shift http://podrezov.com/msx2up/yis503iii_basic-bios2_special.rom
- in the EPROM with Subrom I still have the CPM, but later will replace it with something useful, for example FMPAC BIOS http://podrezov.com/msx2up/yis503iii_msx2sub_cpm.rom
- installed the FMPAC/F4 module, the original Z80 CPU was carefully desoldered and put on top https://github.com/RBSC/F4-FMPAC
- installed 1Mb module designed by Kamil Karimov https://github.com/Wierzbowsky/Yamaha_RAM
- installed the SFG clone into the side slot https://github.com/RBSC/SFG_Clone
- installed the new video board with S-Video and better Composite video https://github.com/RBSC/YamahaVideoBoard
So in the end I got a nicely upgraded MSX2. :) Still thinking of getting a 7MHz upgrade... Also thinking of modifying the BIOS to show the real amount of RAM.
