ISA hard drive controller question

[Fire-Flare]

What's the second pinout for the little cable for?

Every controller card I've seen has one, but only one for the big cable.

Can a second drive be used from that cable alone?

 

[Chuck(G)]

You're probably talking about an MFM/RLL controller. These have 3 connectors for two drives. The larger 34-position connector carries the "control" signals to the drive and is pretty much floppy-type open-collector logic. The smaller 20 position connectors are the "data" connectors and carry the read and write signals to each drive as a differential pair--one 20-position connector per drive.

ESDI also uses a similar 2-cable system for drives (20 and 34 position, coincidentally), so it's important to know what kind of controller you're using.

 

[Fire-Flare]

Does the single control cable mean that the second drive has to be identical?

 

[Chuck(G)]

No, they can be as different as you want, but only one can have terminators installed.