Driver for the Flashjacks cartridge. With this driver loaded in the flashRom, you have access to the SD-Card driver and the Nextor and MSXDOS system.
To compile:
First: sjasm.exe flashjacks.asm
Second: mknexrom Nextor-2.1.2.base.dat FLASHIDE.ROM /d:FlashJacks_driver.bin /m:chgbnk.dat
Sources: