Canon AS-100M Field Service Manual page 22

1.2.13 5" HARD DISK (option)
5" HARD DISK consists of a M4863 hard disk, a MDD220 and power
supply unit.
M4863 connects to H.DISK interface circuit which provides in
MAIN UNIT through the disk controller built-in M4863.
MDD-220 connects to FDD CONT through 5"FDD interface circuit.
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