ESDI drives

From: Pete Turnbull <pete_at_dunnington.u-net.com>
Date: Sat Apr 7 17:05:46 2001

Tony is (almost) correct: ESDI drives use a binary select scheme similar to
SCSI. The three select bits are decoded to enable drives 1,2,...,6,7.
 There's no "drive 0" because that corresponds to the "deselect all drives"
condition.

However, some PC controllers only support two drives (another legacy of the
IBM PC BIOS) and of course they use drives 1 and 2. Therefore, some PC
manufacturers suggest using a cable with a twist, to swap pins 26 and 28
(DS1 and DS2), leaving the select jumpers the same on both drives. I've
never seen a cable with a twist on a "real" ESDI system.

-- 
Pete						Peter Turnbull
						Network Manager
						Dept. of Computer Science
						University of York

Received on Sat Apr 07 2001 - 17:05:46 BST