I am confused by the sentence "Following reception of a sync byte (which is always $AA) actual data is received until /HSHK is de-asserted." But since /HSHK is physically sent on the ReadData line, and the actual data is also sent on that line, I don't understand what that really means. Basically I'd like to see a detailed timing diagram that shows exactly what happens for a normal transfer from the drive to the Mac.

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Basically, the way I read that sentence, I interpret it as this:

Handshake is sent

Sync byte it sent

data is sent

Handshake is checked.

send next byte

check handshake

send next byte

on and on it goes. This is my guess.... But ive been wrong lots of times before

This is where the uncertainty sets in for me, maybe the handshake signal is of specific timing, and thats how the drive knows if its data, or if its a handshake.