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tezza
October 7th, 2008, 03:28 AM
Some time ago I wrote about losing a large proportion of my System 80 (TRS-80 M1 clone) disk collection due to disk aging. I've finally restored the single-density collection to real disks from emulator disk images on my PC.

I've written an account of this (http://www.classic-computers.org.nz/blog/2008-10-05-transferring-disk-images-to-real-disks-for-the-system-80.htm), for those who might be interested in the techniques tried and what did it for me in the end.

Tez

billdeg
October 7th, 2008, 06:53 PM
interesting.

kb2syd
October 8th, 2008, 04:44 AM
Has anyone tried creating SS/SD disks using imagedisk and a compatible PC controller?

I have done it with my Catweasel card and it works well using Tim Mann's tools.

Chuck(G)
October 8th, 2008, 01:57 PM
Has anyone tried creating SS/SD disks using imagedisk and a compatible PC controller?

I have done it with my Catweasel card and it works well using Tim Mann's tools.

It's not possible if you want to recreate Mod I TRSDOS diskettes--the format used a special data address mark for the directory track that the PC can't write.

I believe there are, however, patches and workarounds to TRSDOS for this.

Sharkonwheels
October 8th, 2008, 03:33 PM
That was fixed long ago - Dave Dunfield's ImageDisk (IMD) program can handle those diskettes, as well as Model III/4/4p. I use it with a CompatiCard IV, which can basically read/write about anything out there, so long as software exists. I've done DEC Rainbow RX-50, Altos DS/QD, Altos 8" SS (Shugart SA-801), Osborne 1SS/SD and SS/DD, Kaypro SS/SD and DS/DD, etc...

There's also the utilities that come with some emulators, specifically I've used Jeff Vavasour's utils for TRS-80 disks...check vavasour.ca for more info...

A standard PC FDC will not work, though, but a cheap alternative that MIGHT work, is acquiring an Adaptec AHA-1542B ISA SCSI+FDC card. I can check this weekend, if ou want to know if it will do SD. Those cards are relatively cheap, at $10-30 on fleaBay.

I know other sites mention that the Adaptec AH-1542CF will work, but I have had ZERO success reading single-density with those, and I have acquired 2-3. None worked. 1542B worked fine, though.

dave dunfield's stuff is at www.classiccmp.org/dunfield

Tony

tezza
October 8th, 2008, 04:20 PM
Whilst on this topic, Jason Watton (the writer of Omniflop) is keen to get as many formats as possible implemented in Omniflop including TRS-80 SS-SD formats. Omniflop is a Windows XP/Vista program and will read and write single density disks (at least BBC ones) with a standard PC FDC. It may or may not be possible to do TRSDOS, but Jason is willing to have a crack at trying to get this format implemented in his (free) software.

Whilst acknowledging that there are hardware and software solutions out there for TRS-80 Model 1 single-sided, single density disks, it would be good to have an XP program that could read and write jv1 or dmk images without special hardware.

Can I encourage anyone with single density TRS-80 Model 1 disks to help Jason get this format implemented? What he needs is a few disk maps from people (as read from the disk by Omniflop). It seems my own system (despite what I said about handling BBC sd disks ok) just won't read the single-density TRSDOS and NEWDOS 80 v2 disks properly to map them. Perhaps no-one's can, but it would be useful to find out if this was universal (or not).

You'll need to have an XP machine with a 5.25 inch floppy (high density should be ok). You'll also need 40 or 80 track single-density, single-sided disks that conform to the standard TRSDOS format (directory on track 17 etc.). If nothing else, this is the format to get support for at least, as it's the lowest common denominator. However, other DOSes could be tried as well.

Here is what to do..


Download Omniflop from http://www.omniflop.com/ and install it
Try to read it using the provisional TRSDOS and NEWDOS 80 formats Jason has already installed (it's unlikely to work. but have a go anyway)
If reading fails, use the software to get a disk map of the disk
Send this map to Jason (email is with the software), and give him the details of DOS, format etc. and the PC (make sure at least one of the maps is standard 40 track ss-sd TRSDOS)

He will try to decode it, and fix the support. Technically, if Omniflop can successfully read and write BBC single-sided, single-density disks on a 5.25 inch high density floppy drive on a XP machine, it SHOULD be able to do TRS-DOS also, yes?

Just in case your wondering, I have pointed Jason towards resources that describe in detail the different disk image formats and the way TRS-80 Mod 1 disks are written (i.e.
http://www.tim-mann.org/trs80/dskspec.html (http://www.tim-mann.org/trs80/dskspec.html)and
http://www.discover-net.net/~dmkeil/trs80/trstech.htm
so he's got that info already).

Give it a go!

Terry

Druid6900
October 8th, 2008, 07:23 PM
Ok, I have just such a setup on my main computer.

I just downloaded the software and I have several TRSDOS, NewDOS/NewDOS80 and LDOS disks, so, I will do what I can to help with the development.

MikeS
October 8th, 2008, 08:02 PM
I'm a little confused:

On the Omniflop site he mentions several times that single-density diskettes with a 'normal' PC FDC are not the problem that many people say they are, and that they have only found a few PCs that have trouble with SD; this is indeed contrary to my experience and that of many others.

But I see that in his 'test' for SD compatibility he seems to be using a 3.5" drive; AFAIK 3.5" drives never used single density (i.e. FM), so is he *really* talking about single density 5 1/4" diskettes, or using the term single density to refer to low-capacity 3.5" disks?

I look forward to seeing results reading SD 5 1/4" disks with XP and a standard PC controller.

mike

tezza
October 8th, 2008, 10:30 PM
I can't speak for Jason Mike, but what I do know is that with my bog-standard year 2000 PC (Celeron 500) Asian clone running XP with a high density 1.2 MB drive, I can write 80 track single-density double-sided 5.25 inch disks, which load perfectly into my BBC computer.

It's definitely single-density.

I must admit, I was doubtful before I tried it as I'd read single density is almost impossible without special hardware. I was pleasantly surprise when it worked first time!

Tez

MikeS
October 9th, 2008, 08:46 AM
Well, I don't know anything about BBC computers aside from the fact that they used several different sizes and formats ;-)

AFAIK an 80-track single-density DFS disk would have a capacity of 200KB per side; is that what yours are?

Single-density is another of those ambiguous terms; its classical meaning actually refers to the FM recording method used 'way back then', which some disk controller implementations are simply not capable of. However, in the meantime it has also become commonly used to refer to low-density MFM formats, so there is some confusion.

As I said, I'll be very interested to see if a standard PC can read the original single-density RS disks (~85K/side); prevailing wisdom is that with very few exceptions you need a catweasel or equivalent.

m

Druid6900
October 9th, 2008, 10:36 AM
Well, although I haven't been able to READ any of the floppies I've stuck in the drive (since they aren't in the profiles yet), it does seem to recognize what the diskette parameters are and is generating the diskmap files for them, so, I guess we'll see.

tezza
October 9th, 2008, 11:57 AM
Well, I don't know anything about BBC computers aside from the fact that they used several different sizes and formats ;-)

AFAIK an 80-track single-density DFS disk would have a capacity of 200KB per side; is that what yours are?

Hmm..actually I'm not sure. I'd have to drag it out and wire it up to check. It is DFS.


As I said, I'll be very interested to see if a standard PC can read the original single-density RS disks (~85K/side); prevailing wisdom is that with very few exceptions you need a catweasel or equivalent.

m

Conventional wisdom may well be right, Mike, but Jason seems willing to give it a go so I reckon it's worth sending a few minutes to get him a disk image or two. If he can't do it, then he can't do it. I figure we've got nothing to lose though.

Tez