Xref: utzoo comp.os.os9:1427 comp.sys.m6809:1361 Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!van-bc!ubc-cs!alberta!cpsc.ucalgary.ca!ctycal!ingoldsb From: ingoldsb@ctycal.UUCP (Terry Ingoldsby) Newsgroups: comp.os.os9,comp.sys.m6809 Subject: Re: adding as disk drive to COCO3 Summary: It can be done! Keywords: disk drive, high density, os9 Message-ID: <523@ctycal.UUCP> Date: 18 Jan 91 00:07:44 GMT References: Organization: The City of Calgary, Ab Lines: 44 In article , a.dent@bluemoon.uucp (Bryan Hannahs) writes: > roccella@pilot.njin.net (Matthew Roccella) writes: > > I am trying to add a 1.2 Meg 5.25" disk drive to my COCO3. But > > I keep running into trouble. I made up a new drive cable, cut all the > > traces from my /D0 drive, accept the one that designates the drive as > > /d0, and I made a new OS-9 boot disk with the d1_80dd descripter. > > My trouble is that the system keeps giving me CRC errors and > > BAD SYSTEM TRACK errors. I cannot read, write, or format any disks in > > this new drive at all. My /d0 drive works fine. > Hmm...well, first, if you got the motor running and the drive selected > with your cable and such, I'd like to know what the changes were. I've got > a 1.2meg I've been trying to use on my XT clone. It selects, but the motor > won't run. Same thing happens when I try it on my CoCo. ... > thing that puzzles me is that my XT's controller is SUPPOSED to be able to > handle the 1.2meg AT drives. I think maybe I just have a jumpering I'm not sure about the second poster's problem (i.e. motor won't run), I suspect that there is either something wrong with the drive or you aren't getting the motor on pin wired correctly. The first problem is *easy*. What you don't realize is that the 1.2 MByte floppy disk drives spin faster (350 RPM ??) than the standard 80 track drives (300 RPM). Think about it. You start to lay down the format on the disk. Your CoCo thinks it knows how long it takes for the disk to spin so it writes out formatting info at that pace. Unfortunately for you the disk revolves more quickly and you overwrite the beginning of the track. Simple! There is nothing you can do to fix the controller, you must slow down the drive. Most 1.2 MByte disk drives use motors that have two speeds. Sometimes there is a jumper, sometimes a wire that must be disconnected to select 300 RPM. Do this and you will suddenly have a working drive. Your storage will only be about 700K, *not* 1.2 MByte. Have fun! -- Terry Ingoldsby ctycal!ingoldsb%cpsc.ucalgary.ca Land Information Services or The City of Calgary ...{alberta,ubc-cs,utai}!calgary!ctycal!ingoldsb