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NeXT
June 21st, 2011, 12:48 PM
I'm so used to Rawrite that I have never use Imagedisk.
I have it and my Osborne disk images on a DOS system right now and I'm trying to write to modern double sided high density floppies under the assumption that it won't complain about being formatted to a lower capacity. The thing is that when I start the write it gives a lot of errors and the finished product won't boot the Osborne so something is wrong here. Any tips from a pro?

Chuck(G)
June 21st, 2011, 01:27 PM
DSHD? No, that won't work. You have to use DSDD (360K) media and use a 360K (48 tpi) drive. I just wrote the O1 CP/M system disk on a 386 running MS-DOS 7/Win95 OSR2. No problems at all.

tezza
June 21st, 2011, 02:27 PM
A friend of mine used a high-density drive to write some Kaypro II floppies using imagedisk.

http://www.classic-computers.org.nz/blog/2010-02-18-writing-cpm-from-1.2mb-disks.htm

It doesn't actually say he used DSHD disks though but he did talk about using bulk erased 80 track disks at the end of the article (which sounds like they might have been DSHD)? I should contact him and get some clarity on this.

Tez

Chuck(G)
June 21st, 2011, 02:59 PM
Yes, if you can bulk-erase HD media, you can often get some of them to function as DD. It's not something I'd recommend, but I've seen it work.

By the same token, bulk-erased media written in a 96 tpi drive can be used at 48 tpi.

Few people, however, have a bulk eraser capable of doing the job right.

Also let's not confuse "single density" (FM) with "low density" (medium choice). One can record FM on high-density media (the 250KB "A1" format 8" media are an example of this).

tezza
June 21st, 2011, 03:28 PM
Yes. It certainly saves a whole lot of hassel making CP/M disks (and other old formats) if you just use good old 360k drives and DSDD disks at the PC end. This is what I do. I have an old Pentium MS-DOS machine in the corner especially for it.

Tez

NeXT
June 21st, 2011, 04:45 PM
Well I'll leave the bulk tape eraser along for now and take a new box of DS-DD disks out of inventory and use those.

Edit: Nope. It's still doing nothing but errors. Could this be something with the settings? I'm setting it to single sided and both double and single step don't do much.

Chuck(G)
June 21st, 2011, 04:57 PM
Can you use plain old DOS FORMAT to successfully create an error-free disk?

If not, tell us about your setup (system, drives, BIOS setup for drives, etc.).

MikeS
June 21st, 2011, 05:01 PM
Well I'll leave the bulk tape eraser along for now and take a new box of DS-DD disks out of inventory and use those.An excellent idea, and what you should have done in the first place!

How many times does this have to come up on here: Do NOT use 5.25 HD diskettes in systems using DD disk drives, which is pretty well any system except an IBM AT or later and their clones (although I'm sure Chuck will come up with exceptions). Period. Unless you're on a desert island, can't get DD diskettes, and have a lot of time to waste.

Chuck(G)
June 21st, 2011, 05:20 PM
Every once in awhile on a 5.25" job, I'll see DD data written to an HD floppy. Usually, most of the data's recoverable, even after 20 or so years. But when I see HD data written to a DD floppy, I know that at best, only the first 20-30 cylinders are recoverable. You can actually see the problem if you use something like Kyread*--the edges of the reversals get fuzzier and fuzzier until finally it's all mush.

________________________
* Kyread is one of the last magnetic developers (a suspension of colloidal iron in a HCFC-base). There used to be Magnasee, Visomag and a bunch of other similar products. All used Freon or a related CFC and so were banned and disappeared from the scene. Kyread was reformulated to use an HCFC, and then the owner of the business died. The Geneva Group (http://www.genevainc.com/Contact_Us/contact_us.html) still offers Magview, but you have to call them to find a dealer.

MikeS
June 21st, 2011, 05:35 PM
Every once in awhile on a 5.25" job, I'll see DD data written to an HD floppy. Usually, most of the data's recoverable, even after 20 or so years. But when I see HD data written to a DD floppy, I know that at best, only the first 20-30 cylinders are recoverable. You can actually see the problem if you use something like Kyread*--the edges of the reversals get fuzzier and fuzzier until finally it's all mush.Not surprising, considering the lower flux strength. When you recover DD data from HD disks, do you use a DD drive or an HD one? Is there a difference?

But I don't get why folks knowingly ask for trouble by using the wrong disk type, especially when the correct ones are readily available. "I'm using the wrong type of disk in my computer and I'm getting errors; any idea what the problem might be?" Ummm, let's see...

Even with 3.5" diskettes where you can probably get away with it: if I had a system that uses DD diskettes why wouldn't I just buy a box of them instead of futzing around taping up the HD disks' density holes...

Since this is the CP/M forum: did any CP/M systems ever originally use HD drives and diskettes?

Brendan
June 21st, 2011, 05:53 PM
I, too, had problems with ImageDisk in various systems until I dropped a Tandy 1000 5 1/4" DD drive into my AST 386-33 box. Then, it was turning out floppies for both my Osborne and TRS-80 systems without a hitch. I was also able to image off some of my TRS-80 floppies that needed archiving. All-in-all, ImageDisk works quite well, assuming the disk controller has the capability to drive the DD drive. Remember to use the testfdc.com tool that it comes with to save yourself headaches.

Chuck(G)
June 21st, 2011, 07:31 PM
I use HD drives unless there's some overwhelming requirement to use DD (either 96 or 48 tpi).

In the x86 world, there were several systems running CP/M; the IBM 5170 would run CP/M-86 just fine. Were there any Z80 systems? I don't know--although retrofitting one with a 1.2M HD drive from an 8" drive is duck soup.

NeXT
June 21st, 2011, 08:02 PM
I really don't know much about the system other than it's your generic clone AT with a 1.2mb 5.25" drive.
I never looked inside it before but I used it in the past for data recovery on a customer's floppy disks.
I can successfully format DD disks in it using format /4 so that's all okay and I can read and write normally using the drive.

Chuck(G)
June 21st, 2011, 08:12 PM
Since you're using a 1.2M drive, have you tried setting 250Kbps->300Kbps and double step on?

The reason for this is that a 1.2M drive is 96 tpi and spins at 360 RPM. The drives on your Osborne are 48 tpi and spin at 300. So you have to goose the bitclock when writing up to match the speed of the floppy.

Also, if a 1.2M is all you've got, use a fully degaussed DD floppy. Otherwise the garbage left on the odd-numbered tracks is going to confuse your Osborne 48 tpi drives.

MikeS
June 21st, 2011, 09:06 PM
I really don't know much about the system other than it's your generic clone AT with a 1.2mb 5.25" drive.Ah, you didn't say, so I assumed your DOS system had DD drives which would likely cause problems writing HD disks. I think I've used ImageDisk to make DD disks with an HD drive without problems but wouldn't swear to it; have you checked the configuration carefully, especially sides, single/double step etc.?

I'll try it tomorrow if I remember.

Even with the DD disks, you're still getting lots of errors when you write the disks on the AT?

NeXT
June 21st, 2011, 10:03 PM
Nope. Not a thing. Mainly because I have never run into these problems.

atod
June 21st, 2011, 11:03 PM
Doesn't the RPM need adjustment when using a HD drive as DD? Please excuse me if this was already posted

Chuck(G)
June 22nd, 2011, 08:20 AM
Doesn't the RPM need adjustment when using a HD drive as DD? Please excuse me if this was already posted

That's not a simple question, believe it or not.

To understand the issue, a useful bit of information is that 1.2M 5" drives have their origin in Japanese PC98 equipment, where they're pretty much just a reduction of the PC98 8" drive (there is also a PC98-compatible 3" drive that spins at 360RPM, just like the 5" and 8" drives). The idea on the PC98 machines is that the recording format is unchanged, regardless of the medium size.

The western 5" tradition is a bit different, starting with the Shugart SA-400, with 35 single-sided tracks recorded at 48 tpi on a disk spinning at 300 RPM. The Micropolis-origin 100 TPI drives were intended to come closer to 8" with 77 tracks, but they're mostly a historical curiosity. At some point, as things got better, a "quad density" 96 TPI format was introduced.

Early on, a number of makers decided that a single drive model could satisfy the needs of the 96 tpi world. So, instead of selling, say, Teac FD55F (720K) and Teac FD55G (1.2M) drives, a Teac FD55GF drive could satisfy both markets (I do have some 1.2M only drives on the shelf). There were two ways to accommodate this.

One way was to have a "dual speed" drive, where the drive spindle speed changes according to the selected density. I still have a couple of PC floppy controllers with jumpers to accommodate these drives.

The other way was to keep the spindle speed at 360RPM and add a 300KHz bit clock to the controller, rather than the normal 250KHz one used for 360K drives.

Most Teac 5" high-density drives have jumpers that allow the drive to operate in either mode.

So there's your answer--you can change the spindle speed (which almost nobody today does, thanks to the original PC AT, or you can change the bit clock, which everyone does.

Sort of a "Don't raise the bridge, lower the river approach"... :)

NeXT
June 22nd, 2011, 12:12 PM
So in non rocket science terms I need a DS-DD drive in the system as well.

glitch
June 22nd, 2011, 12:27 PM
I wrote my Kaypro II system disks using DSDD media in a DSHD drive. They were bulk erased DSDD disks (used a TV degauss ring), and you do need to set ImageDisk to do the bitrate translation and double-stepping. It will work, but **DO NOT** write data with a DSDD drive if the disk was formatted/written in a DSHD drive and expect the DSHD drive to be able to write over it. The DSHD drive's track width is too narrow to reliably write over the DSDD-written tracks.

If you're going to write DSDD disks out with a DSHD drive (I do it quite a bit), I recommend transferring the contents of the disk over to a DSDD disk in your target system's DSDD floppy drive.

Chuck(G)
June 22nd, 2011, 01:01 PM
So in non rocket science terms I need a DS-DD drive in the system as well.

That's advisable, but as I said, if you can bulk-erase a floppy before writing it, you'll be fine. I use a VHS tape bulk eraser, but those things are getting to be pretty uncommon now.

NeXT
June 22nd, 2011, 03:15 PM
I need to bulk erase the DS-DD disk before I can use it in a DS-HD drive? I'm a bit confused on that bit.
The bulk eraser is a bit old.the Realistic 44-210. It's old enough the box art shows someone erasing a reel and an 8-track. :)
http://www.shizaudio.ru/audio/data/media/47/Realistic%20Magnetic%20Bulk%20Tape%20Eraser%2044-210.JPG

Chuck(G)
June 22nd, 2011, 05:30 PM
That should do it.

The reason is that a 96 tpi drive writes a track only half as wide as a 48 tpi one (the kind the O1 has)--and you're writing every other track (double-stepping) So if you don't bulk-erase a DD disk before using it, the O1 drive head will also pick up the background "noise" between tracks and create read errors.

NeXT
July 13th, 2011, 11:12 AM
Okay, so I move Imagedisk and the disk images over to an AT&T PC 6300 which is fitted with a 360K double density drive.
I fire up Imagedisk and try to write:



0 sectors
Write Complete

...and that happens. It does nothing.

Chuck(G)
July 13th, 2011, 01:05 PM
PC Compatibility issue, perhaps? Have you tried running Dave's test program?

NeXT
July 13th, 2011, 02:35 PM
The included drive test program?
Huh, well apparently failed on the first test.
So much for 100% compatibility. :P