Path: utzoo!mnetor!tmsoft!torsqnt!lethe!yunexus!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!cs.utexas.edu!rice!uw-beaver!cornell!rochester!pt.cs.cmu.edu!o.gp.cs.cmu.edu!andrew.cmu.edu!rh2y+ From: rh2y+@andrew.cmu.edu (Russell E. Hoffman, II) Newsgroups: comp.sys.m6809 Subject: Re: Coco Drive Select 4 Message-ID: Date: 9 Feb 91 02:35:04 GMT Organization: Carnegie Mellon, Pittsburgh, PA Lines: 22 > ... [paraphrase] ... explain the drive select/side select mechanism... As I best recall it from when I used to hack around on the CoCo, the line that SS is tied to internally can either be tied to SS, leaving no DS3 (drive sel. 3), or can be tied to DS3, leaving no SS. In plain words, depending on how you set a particular register and how you've built your cable, you can have one of two maximum possible configurations: 1.) 3 double-sided drives (up to 720k each, if they're 80 tracks) 2.) 4 single-sided drives. It's generally preferable to chose option 1, as this gives you six total sides, as opposed to four as in option two. As i recall, OS9 supports option 1, provided you have a straight cable with all the pins in place, so long as you have the right device driver/descriptor. Hope that helps, Russell Hoffman rh2y+@andrew.cmu.edu Carnegie Mellon University