First of all you will need a SD card (not a SDHC card)
Format it as a FAT16 system (I tried 2Gb, but in my OCM it was not readable, so I'm using 1 Gb cards)
If you want the system to remember settings like SET SCREEN and column width, you have to copy MSXBIOS.DAT as the first file om the card. www.msx.org/forumtopic8477.html
After this you can copy COMMAND2.COM & MSXDOS2.SYS and you'll have a bootable SD Card for the OCM
Hi! 10 years later ... I'd like to cerate a new bootable SD card for the one chip to replace a working one which only has 128Mb... but I can not find SD cards bud SDHC... I read above SDHC won't work... is that true? why? any alternative? thanks for your time!
SDHC works fine in current firmware and has been supported for a while (not sure if it 10 years) so you may have to upgrade your firmware to get it working. But you can flash the firmware from the 128MB SD you have now.