ingoldsb@ctycal.UUCP (Terry Ingoldsby) (01/18/91)
In article <RXweV6w163w@bluemoon.uucp>, 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
dclemans@mentorg.com (Dave Clemans @ APD x1292) (01/22/91)
From article <523@ctycal.UUCP>, by ingoldsb@ctycal.UUCP (Terry Ingoldsby): > 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. > To clarify things, 1.2 Meg drives DO NOT!! spin faster than other drives. The disk moves at EXACTLY the same speed. The difference between them is in the electronics. 1.2 Meg drives are clocked twice as fast as the slower drives. Controllers that can handle both drives have the ability to switch clock rates. dgc
wilker@gauss.math.purdue.edu (Clarence Wilkerson) (01/22/91)
Sorry to contradict the last posting, but 1.2 meg drives intended for IBM AT clones do spin at 360 RPM, with a data transfer rate of 300 K-bits per second, instead of the standard for older 5.25" drives of 250 kbs.at 300 RPM. Notice that if you write a disk on a drive at 250 kbs at 300 RPM, the bits have the same density as 300 kbs at 360 RPM. So diskettes written either way or interchangeable at the standard double density. However, when writing a 15 sector HD disk, the AT uses a data rate of 500 kbs, which is not quite twice the double density rate. Finally, the 1.44 meg 3.5" drives also use 500 kbs at 300 RPMs to pack 18 sectors on a track instead of the 9 at lower speed. Clarence Wilkerson
tony@mwuk.UUCP (Tony Mountifield) (01/22/91)
In article <1991Jan21.180211.11345@mentorg.com> dclemans@mentorg.com (Dave Clemans @ APD x1292) writes: > From article <523@ctycal.UUCP>, by ingoldsb@ctycal.UUCP (Terry Ingoldsby): > > 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 [.............] > > To clarify things, 1.2 Meg drives DO NOT!! spin faster than other drives. > The disk moves at EXACTLY the same speed. > > The difference between them is in the electronics. 1.2 Meg drives are clocked > twice as fast as the slower drives. Controllers that can handle both drives > have the ability to switch clock rates. In actual fact, what Terry said is correct. To clarify: At double density, both 3.5" and 5.25" drives run at 300rpm and are clocked at 250kHz. This gives the standard 720k storage. At high density, both types of drive are clocked at 500kHz. The 3.5" drive still rotates at 300rpm, so this gives exactly double the capacity, i.e. 1.44M. However, 5.25" drives in high density *ARE* rotated faster, at 360rpm. This is why they only give 1.2M instead of 1.44M - the rotation period is shorter. Both types of drive are normally switched between the two modes by a signal on pin 2. This switches timings in the electronics, and in the case of 5.25" drives also changes the motor speed. It is necessary for the disk controller to match its clock rate with the pin 2 setting. Tony. -- Tony Mountifield. | Microware Systems (UK) Ltd. MAIL: tony@mwuk.uucp | Leylands Farm, Nobs Crook, INET: tony%mwuk.uucp@ukc.ac.uk | Colden Common, WINCHESTER, SO21 1TH. UUCP: ...!mcsun!ukc!mwuk!tony | Tel: 0703 601990 Fax: 0703 601991 **** OS-9, OS-9000 Real Time Systems **** MS-DOS - just say "No!" ****
avalon@coombs.anu.edu.au (avalon) (01/23/91)
dclemans@mentorg.com (Dave Clemans @ APD x1292) writes: >From article <523@ctycal.UUCP>, by ingoldsb@ctycal.UUCP (Terry Ingoldsby): >> 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. >> >To clarify things, 1.2 Meg drives DO NOT!! spin faster than other drives. >The disk moves at EXACTLY the same speed. >The difference between them is in the electronics. 1.2 Meg drives are clocked >twice as fast as the slower drives. Controllers that can handle both drives >have the ability to switch clock rates. I have run a 1.2MB drive on my coco while using some utility program that shows disk rotation speed in RPM/ 1.2 drives go around at about 360+rpm and 720K drives at about 300 rpm (same as 360K drives). -avalon
slsw2@cc.usu.edu (01/26/91)
In article <avalon.664560280@coombs>, avalon@coombs.anu.edu.au (avalon) writes: > dclemans@mentorg.com (Dave Clemans @ APD x1292) writes: > >>From article <523@ctycal.UUCP>, by ingoldsb@ctycal.UUCP (Terry Ingoldsby): >>> 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. >>> > >>To clarify things, 1.2 Meg drives DO NOT!! spin faster than other drives. >>The disk moves at EXACTLY the same speed. > >>The difference between them is in the electronics. 1.2 Meg drives are clocked >>twice as fast as the slower drives. Controllers that can handle both drives >>have the ability to switch clock rates. > > I have run a 1.2MB drive on my coco while using some utility program > that shows disk rotation speed in RPM/ 1.2 drives go around at about > 360+rpm and 720K drives at about 300 rpm (same as 360K drives). 1.2 meg drives spin at 360 RPM because that's how fast 8" drives spun and a 1.2 meg drive has the same characteristics of an 8" drive. Really. IBM's original AT drive could not change speed, so it ran at 360 RPM regardless of the data rate. That's why an AT controller does 250 KHz, 500 KHz, and 300 KHz data rates; 250 is normal, 500 is 1.2 M, and 300 is normal in a 360 RPM drive. Good drives (TEAC FD55's, for instance) will change speed so that the disk controller only has to handle 500 KHz and 250 KHz. Oh yeah. I've noticed a tendency for PC drives to have the drive select jumpers soldered in at DS 1 since *everyone* has an AT and therefore *everyone* uses a twist in the cable so that all the drives are jumpered at DS 1. Being an old CP/M guy, this drives me nuts. Don't mind me; just passing through... -- =============================================================================== Roger Ivie 35 S 300 W Logan, Ut. 84321 (801) 752-8633 ===============================================================================