PC Ephemera

In the IBM Personal Computer Technical Reference Manual, of course. How low-level do you want. The spec for the BIOS-level interface seems to be : Int 15h On entry, request type is in AH, as follows AH=0 : turn motor on AH=1 : turn motor off AH=2 : Read Tape Block. Read CX bytes into memory starting at ES:BX. Return actuall number of bytes read in DX. Return status in AH AH=3 : Write tape block. Write CX bytes to cassette starting at ES:BX. Return status in AH Status (note, carry is set on any error) AH=0 : No errors AH=1 : CRC error in read block AH=2 : No data transsitions AH=4 : No leader AH=80 : Invalid command There's a lot more, including descriptions of the tape waveformas and the block format, but I'll only type all this in if you need it. -tony