Converting TRS-80 Disks to Virtual (and Back Again if you need it)

The Problem:

Modern hardware and operating systems are making it more difficult to convert actual TRS-80 disks into an emulator (DMK or DSK) format.

Some of the obstacles are:

  • No ability to read single density disks whatsoever
  • Current operating systems do not allow for direct hardware addressing
  • No 5.25″ drive support in the BIOS
  • Degrading media (See Warning below)

Different Methods:

There are a number of different methods you can try, all of which are covered on this page:

  • Send them to me
  • Ancient PC
  • Modern Day Solutions

Send them to me:

Disks which are 35+ year old may have no more than 1 good read on them. If the disks were exposed to any level of humidity over the past 35+ years, odds are that the mylar will separate on the first read. While I cannot guarantee results, I can guarantee that if you try to read them first, I won’t be able to. Please see this FAQ.

WARNING!!!!

Before putting a disk in your drive, make sure to inspect it. Improperly stored disks will degrade, and will shred in your drive. Inserting one of these disks in your drive will not only produce a disheartening noise, but will likely coat your read/write head with oxide, requiring you to clean the heads. Here are some pictures I took of some of these improperly stored or otherwise decayed disks.

Ancient PC:

Reading single-density disks (which is what the Model I used; noting that even double density disks tended to have a single density track 0) is MUCH more complicated. “Modern” computers do not have the crystal needed to generate a single density clock, so they simply cannot read single density. Even those that can will have trouble with TRSDOS 2.x (DAM problem) or NEWDOS/80 v1.x (DAM problem) or NEWDOS/80 v2.0 (Inner Track Problem).

To use a really old PC, you need to be operating in either pure MSDOS or Windows ’98 and earlier as those are the only operating systems that allow you to access the hardware directly. If you are going the Windows ’98 or earlier route, you should set your system to boot straight into DOS instead of going into the GUI. To do this click START -> SHUTDOWN -> SHUTDOWN IN MSDOS. Then once in DOS type CD \ to get to the root directory. Then enter attrib msdos.sys -r -a -s -h. Then enter edit msdos.sys. Then find where it says BOOTGUI=1 and change 1 to 0. Once you do that, the next reboot should go straight to MSDOS.

Once you are set with a PC that boots straight to DOS, the next thing you should do is run Dave Dunfield’s PCTest Utility which will check your floppy drive controller to see how well it will read and write single density and double density disks. You can download that utility here.

  • The Adaptec 1522 SCSI controller (ISA, non-bus-mastering, NS8473 Controller) can read/write/format FM (Single Density) floppies, including LDOS-format SD floppies. TRSDOS2.3 directory tracks CANNOT be handled on these because of the DAM.
  • It is possible that the Adaptec 1542 SCSI controller (ISA, bus-mastering, NS8473 Controller)
  • The Acculogic ISApport SCSI adapters (SMC FDC37C65) will read 360K Double Density but will not read single density on a 1.2MB HD drive.

If you have a PC (with a 5.25″ drive, of course), booting into pure DOS, that can read/write single and double density, then you would use the following programs and/or utilities:

Reading/Writing TRS-80 Disk Media on a PC

If you have a 5.25″ drive hooked up to your IBM PC, the following programs can be used to read TRS-80 disks into the DMK/DSK format. If you want to read Model 1/3/4 disks and have a Catweasel card, use Tim Mann’s CW2DMK utility. If you want to read Model 1/3/4 disks and do not have a Catweasel card, use Matt Read’s READDISK utility. If you want to read COCO disks, use Jeff Vavasour’s RETRIEVE utility.

Utility Name
Platform
Last Updated
Author
Home Page
David Keil’s Emulators
DOS
1998
David M Keil
N/A

David Keil’s emulators permit mounting a physical drive attached to a PC as a virtual disk drive inside the emulator. The floppy disk selection screen can be accessed inside the emulator by pressing the F9 key. Once on that screen, for example, if you wanted to backup a TRSDOS image in virtual drive :0 onto a real disk mounted in the PC Drive A: you would simply configure virtual drive :1 inside the emulator to be A:. Going this route has the virtual TRS-80 making the images, so any limitations of the TRS-80 in terms of backing up a disk would apply to this scenario.

David’s Model I emulator can be downloaded here, David’s Model III/4 emulator can be downloaded here.


Matthew Reed’s DOS Emulators
DOS
2004
David M Keil

Similar to David Keil’s emulators, Matthew Reed’s DOS emulators permit mounting a physical drive attached to a PC as a virtual disk drive inside the emulator. The floppy disk selection screen can be accessed inside the emulator by pressing the F8 key. Once on that screen, for example, if you wanted to backup a TRSDOS image in virtual drive :0 onto a real disk mounted in the PC Drive A: you would simply configure virtual drive :1 inside the emulator to be A:. Going this route has the virtual TRS-80 making the images, so any limitations of the TRS-80 in terms of backing up a disk would apply to this scenario.

Matthew’s Model I/III emulator can be downloaded here, Matthew’s Model 4 emulator can be downloaded here. Note: Matthew’s emulators do NOT come with the ROMs, which need to be downloaded elsewhere.


TRS-80
Jan 5, 1999
Timothy Purves

Transfer runs on a TRS-80 and will read/write to IBM PC Formatted 5.25″ disks.


The TRS-80 Model 4 Emulator’s virtual disk utilities have been provided free for download in order to allow you to determine whether your PC has the features necessary to read and write TRS-80 floppies directly. The emulator can either access your TRS-80 floppies directly in its floppy drive, or as images copied to your hard drive. Either way, you need to be able to determine whether the PC hardware can read the floppies.


Reading, writing, editing and formatting TRS-80 disks on a PC.


DOS
Mar 20, 1990
Powersoft


Standalone utility to transfer files from a COCO Diskette to a .DSK image.


READDISK transfers files from a TRS-80 Diskette to an IBM .DSK file without special equipment. This version can also read Tandy 1000 disks.

Please note that not all PC disk controllers are capable of reading TRS-80 disks. This is a limitation of the disk controller, not READDISK. If you have trouble, try running READDISK on other PC’s until you find one that can read your disks. Remember, you only need to read your TRS-80 disks once to convert them to disk images, so be sure to use the “Retry” command heavily.


Modern Day Solutions:

There are a number of third party products which can be used, to varying degrees of success, to read and TRS-80 disks.

Inside a PC:

Attached to a PC via USB (“Flux Readers”):

Inside a TRS-80:

I am not a fan of Flux readers. Flux readers are not made to error check. They are made to read the pulses on the disk and store them in a virtual format. Did you get a good read? Did you do a good write? The Flux reader won’t know or care and because of this, it didn’t know it should retry the read and maybe get a better one.

The other thing I do not like about Flux readers is that conversion from their various proprietary formats relies ENTIRELY on HxCFloppyEmulator software. At the very least, there would be no way to convert special formats or copy protected disks to DSK or DMK format if you read them into a different format first.

Currently, only the Catweasel is free of such issues as it has software which will read and write directly to and from DMK but it is not currently in production:

Utility Name
Platform
Last Updated
Author
Home Page
Catweasel Utilities v4.7.0
April 13, 2021
Quentin Barnes

Utilizes special hardware called a Catweasel card to read all formats of TRS-80 disks on a PC. Also includes a utility of general use for converting DMK format disks to DSK format.

4 Comments

  1. I recently used spark plug cleaner to clean disks in bad condition and was able to read data from them after a little spray straight on to the platter ! as a last resort I was amazed it worked 🙂

    Reply
  2. I have a couple of 5 1/4 floppy disks that have our Christmas letters from 1982 & 1983 on them. I would like to get this data recovered. Any idea where I can go to get this done?

    Reply
  3. I have a TRS-80 Color Computer 3 and an original color computer disk drive, and I got my cassette programs onto disk on my own. However, I have no clue how to get my programs from the floppy disks into a virtual format that I could preserve on modern equipment, and I really wish I could do that. I do have a late 1980s/early 90s DOS/Windows 3.1 PC with a 5 1/4 floppy and a 3.5 floppy, and a late 1990s PC with a 3.5 floppy and a CD-R/W, and a couple of newer machines. But the PC could not read the TRS-80 disks, which I imagine is a problem of format but I am not up on these things. My programs are all basic and I saved them in ASCII format, but I’m guessing the problem is deeper than that. If you have the know-how and the equipment, I’d be happy to pay for a conversion of my disk (I have one disk to convert, at most I may have a second one but as of now I just have one). Thoughts?

    Reply
  4. Hello I have hundreds of 5 1/4 Double Density floppies formatted for MS DOS. I would like to have these converted to a contemporary media, is it possible? It’s for an archive project for a writer.
    Thank you

    Reply

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