According to the Functional Characteristics the 2315 drive had 200 cylinders + 3 spare. Each cylinder consisted of 16 sectors of 366 bytes each.
It supported '0001011' + 1 byte for seek cylinder.
???????????? 'hsss1010' for read. Read begins at h(Head), sss(Sector) and continues to end of track
???????????? 'hsss1001' for write. It began at given sector until end of track, if there was not enough data the rest of the track was written as 0.
??????????? '00000010' Read IPL, '00000011' NOP, '00000100' Sense.
The 44 supported most of the RR, RX, RS, and SI instructions. According to docs it did not support LM/STM, BXH, BXLE but they are used in MPS/44.
The 44 also allowed for instructions do be placed in bump storage and on illegal opcode it could transfer to bump storage to be executed.
Rich
