The N88-BASIC disk format is the one used by the operating system of the same name for the Japanese PC8800 and PC98 computers. It is another IBM scheme variant, and is very similar to some mixed-format CP/M disk formats, where track 0 side 0 uses 128-byte single density sectors and the rest of the disk uses 512-byte double density sectors. (The reason for this is that the PC8800 boot ROM could only read single density data.)
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To read:
fluxengine read n88basic -s drive:0 -o n88basic.img
To write:
fluxengine write n88basic -d drive:0 -i n88basic.img