Hi, thanks a lot for the report, I'm sure it'll help other Tandy users at some point. 😀

Just a few thoughts of mine to this issue:

- DOS 3.2 pre-dated the usual FAT16B (aka Big DOS).
- S0KILL runs on DOS and can wipe any media's track 0
- later versions of DOS support FORMAT C: /B , which reserves some free space for the system files
- using a small CF or SD card (<= 512MB or <= 32MB) might avoid issues with old DOSes
- some DOS 3.3x from Compaq was said to support larger partitions

I have a nearly identical setup, even the CF card, except I'm using the Lo-tech ISA CompactFlash adapter that I built from a kit. (And the IDE-CF adapter might be from Syba or Startech instead of Addonics.)

The hard drive I replaced was a 40MB one from 1991 or so, and I remember having to use MLPART.SYS to use the last 8MB of it. This time I decided to go straight to Tandy MS-DOS 3.3 to retain Tandy's MODE.COM and BASIC but avoid drive space issues (I can't remember if MLPART.SYS could be used more than once or if you're limited to only one additional partition). Due to a lack of working systems with 360K drives I bootstrapped the OS using the serial drive feature of the XTIDE BIOS (I swapped out the 8250-based Tandy serial card with a dual-16550-based Startech one at the same time to make this practical). I don't recall any issues partitioning and booting the CF card from DOS 3.3, but I wiped the first megabyte or so of it ahead of time using dd in Linux and it's possible I built the initial partition table there and did an FDISK /MBR from another DOS later.

I've only used up to drive F: so far. Even a 1GB drive is overkill for the OS (limited to 24 partitions of 32MB=768MB total) but probably also the system itself, as there's only so much software one can run on it. Too bad the 2GB drive was the smallest I had at the time...

Yeah, I realized afterwards that I could've just used a 1GB card since the max is 768MB.

I'm not sure what you mean by the serial drive feature of the XTIDE BIOS, to be honest. I am interesting in getting a card for it though that will let me use a serial mouse. Would any 8-bit ISA that has a serial port work?

infiniteclouds wrote:

My intention was to continue to use the Tandy MS-DOS 3.2 that shipped with the SX to avoid losing some of Tandy specific MODE features as well as issues with 3.5" Double-Density drive formatting.

If you ever feel like using a newer version of DOS, SETVER and DRIVPARM can get you around those two issues. I'm not sure I could tolerate having a bunch of 32MB partitions, personally. 😀

Well, there were other reasons, too like additional memory eaten by newer versions of DOS when I only have 640K. My EXPRESS.SYS eats up about 2K and I forget how much ctmouse takes when I eventually get a serial card. DIR also feels pretty slow with a 2GB partition.

I read about DRIVPARM (I might even need it with 3.3 I think?) but I'm not familiar with SERVER -- how does that work?

If I ever get my hands on a TL I might just do the full 2GB drive. I have a CPU upgrade for a 286 socket, too, but it sounds like there were many headaches along the way for your own TL's upgrades.

infiniteclouds wrote:

Well, there were other reasons, too like additional memory eaten by newer versions of DOS when I only have 640K.

Assuming default "DOSDATA" allocations and such, I think the memory difference between DOS 3.3 and 6.22 is less than 10K?

DIR also feels pretty slow with a 2GB partition.

If you don't mind a bare directory listing, one solution for this is to either add "set dircmd=/b" to AUTOEXEC.BAT, or supply the "/b" switch when using the DIR command.

...but I'm not familiar with SERVER -- how does that work?

SETVER exists solely to spoof the DOS version reported to a user-definable list of programs. In DOS 5.0 and above, you'd load it at boot via CONFIG.SYS. The memory footprint is negligible, and even more so if you replace the "built-in" program list with only desired entries. With my Tandy systems, only MODE.COM is serviced.

...it sounds like there were many headaches along the way for your own TL's upgrades.

Not so much headaches as "adventures in problem-solving." 😉

It would be interesting to compare dumps of the boot sector and MBR from a working Tandy DOS 3.2 setup with the ones from a failed attempt. It's supposed to officially support a 32MB disk/partition right? And then there is a proprietary scheme to extend beyond 32MB? I wonder how far it could be pushed with some manual tweaking with a sector editor.

Does having a huge number of drive letters eat up conventional memory?

bakemono wrote:

Does having a huge number of drive letters eat up conventional memory?

If you can tell me how to check my memory in DOS 3.x I'll let you know 😁

infiniteclouds wrote:

I'm not sure what you mean by the serial drive feature of the XTIDE BIOS, to be honest. I am interesting in getting a card for it though that will let me use a serial mouse. Would any 8-bit ISA that has a serial port work?

The BIOS can emulate both floppy and hard disks over a serial connection assuming an appropriate server is running on the system on the other end. Both the original and replacement websites for the BIOS seem to have disappeared, but the instructions are still available on the RetroBrew Computers Wiki and a Windows version of the server is available in the downloads on the Lo-tech.co.uk website (a Linux port is on GitHub).

I guess it depends on the card, but I don't see why any ISA card with a standard serial port wouldn't work, assuming anything else on it (e.g. parallel port, joystick, IDE interface) could either be disabled or doesn't conflict with the 1000SX's existing hardware.

Thanks very much to all of you for this information. I am new to vintage hardware. I recently acquired a Tandy 1000SX but only 1 of the 5.25 inch FDDs works, and the 20M hard card can't be read. I can get a C: prompt, but nothing more.

I have ordered a Lo-Tech XT-IDE adapter and CF adapter from TexElec and am planning on setting them up as described here, but just realized I have one problem. I have only DOS 3.3 on FDs, and these instructions call for booting from DOS 5.0, which I can't. I have DOS 5.0 images, but not on 5.25 FDs.

Maybe this workaround will work: I install DOS 3.3 on the CF, then use my Win 10 PC to copy the DOS 5.0 FDISK.EXE to the CF and then go back to the Tandy and copy 5.0 FDISK to the DOS 3.3 FD and start over. Thoughts? Thanks again.

Hello Tom and welcome to Vogons! I'm not sure if it works, but you could give it a try.
From what I remember, my copy of PC-DOS 3.30 supported FAT12 and FAT16, but not FAT16B.
FAT16B or "BigDOS" became the FAT as we know it. It was introduced with MS-/PC-DOS 4.x, but people didn't really
use it until ~ DOS 5.0 (except when using other DOSes; there's a funny video to DOS 5, in case you missed it. 😉 ).
As far as I'm aware of, the last/latest release of Compaq DOS 3.x also had got support for large partitions.
Anyway, the XT-IDE should also work just fine with DOS 3.x, albeit with the ~32MB partition limit still in force.

Thanks very much for the reply, but the issue I am facing is not the partition size -I don't mind 32M, at least not yet- It is the issue reported and resolved by the original post:

infiniteclouds wrote:

When I would reboot however, the Lo-tech BIOS would hang at Booting C>>C:. If I booted from disk I could then C: and use DOS on […]
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When I would reboot however, the Lo-tech BIOS would hang at Booting C>>C:. If I booted from disk I could then C: and use DOS on the CF drive fine -- it just wouldn't boot.
<snip>
After experimenting for a while I found that the issue was the FDISK utilities of the 3.x DOS.
<snip>
The following steps got me a working, bootable Tandy MS-DOS on the machine itself:
<snip>
- On the Tandy, booted from MS-DOS 5.0...

I have only DOS 3 on floppy disk, so I can't boot the Tandy from anything else. I suppose the simplest solution would be to obtain DOS 5 on 5.25 inch FD. Any suggestions on how I might do that? Thanks again.

I see. Well, FDISK really could be the issue then. In DOS 2 and DOS 3 times, DOS was usually modified by manufacturers/vendores/etc.
-> Lots of OEM releases of DOS were around. Makers of such DOS releases of that time often included their own utilties,
so that an FDISK or FORMAT from one maker could be different than that of another one.

Tom Servo wrote:

I suppose the simplest solution would be to obtain DOS 5 on 5.25 inch FD.

I'm afraid, yes. It doesn't have to be the complete set, though. Just a boot disk with the appropriate files.
After the CF card is partitioned, formated and bootable, you can copy over the config files and the DOS directory
(which you got earlier, for example, by installing DOS5 on another PC or in an emulator, such as PCem/86Box).

If you can get hold of a cheap copy of DOS 4/5 disks on eBay, the flea market, garage sale or if you see an advert
(small advertisements) in a newspaper, then that's okay, too.

Tom Servo wrote:

Any suggestions on how I might do that?

Hmm. If you've got at least one blank 5.25" floppy disk for your Tandy, you're set.
All it needs is a bootable DOS5 floppy with FDISK, FORMAT and SYS, after all.
The problem is how, to do that from the Tandy ? Hmm. 😕
What worked for me on my PC/XT clone, was transfering a tiny floppy image (**.ima) containing a bootable copy of DOS
over to the old 20MB HDD of my old PC. From there, I ran Disk Copy Fast and wrote the image back to a physical floppy.
Since you've got no HDD, you would need another temporary storage. Maybe a RAM disk, another floppy drive or
that SD card adapter for parallel port (see MicroProject by Matze).

Another idea: XT-IDE can boot from serial, maybe you can use a null-modem or something to make a connection to another old PC.
I haven't tried yet, but there's a host utility that can be set up on another PC, emulating an HDD or something.
If that doesn't work, you can give classics such Ultrafast Filetransfer Operation, Norton Commander (v5 ?) or COMDrive and COMX a try.

Last, but not least, you can also install XT-IDE in an other old PC and do the DOS5 installation from there.
Since the XTIDE Universal BIOS (XT flavor) will be doing the job anyway, the CF card should be handled the same way as in your Tandy.
(The only main difference is, that XT-IDE was meant for XT computers, so the I/O ports will be non-standard for an AT system.
However, that shouldn't be a big issue, since XT-IDE hardware was meant for these I/O ports.)

Tom Servo wrote:

Thanks again.

You're welcome. 😀

Edit: Please check your PM inbox. I've created a small bootable HDD image for you using XTIDE BIOS and DOS5.
Just use Win32 Disk Imager on your modern PC and write the image onto your CF card using an USB card reader (CF must be 500MB or larger in capacity).
From there onwards, you can finish your DOS5 installation, make 5.25" boot floppies on your Tandy, etc.
Hope it works, good luck! 😀

Jo22 wrote:

Edit: Please check your PM inbox. I've created a small bootable HDD image for you using XTIDE BIOS and DOS5.

Thank you very much. That was very kind of you. I'll let you know how it goes, but I don't have the XT-IDE adapter yet; It is in transit.

Thanks, Jo22, but I'm not having much success. I was unable to write the DOS 5 image to the CF. Using Win Image 32, when I clicked 'verify', it had an error immediaetly, something like 'error at sector 0'. I want ahead and clicked 'write' and it had 'Error 5: Access denied'. So I proceeded to use the instructions from the OP and got the same result: a working C drive that does everything except boot. One difference is that when I issued the command 'fdisk /mbr', it just started fdisk & displayed the menu, ignoring the /mbr. That does explain the failure to boot, though: no master boot record.

I'm interested in the VM option, but after formatting the CF in the Tandy, it is no longer recognized by my Win 10 PC. I will look into the vm's you mentioned. I don't have any other old hardware, so I can't try those suggestions. The one working FDD is 360K, so I'm not very optimistic about finding DOS 5 on a 360K FD.

Thanks again.

I think I found a solution. An eBay seller has DOS utility disks, v6.22, including format, fdisk and sys on 360K, 5.25 inch FD. I contacted them and asked about full installation disks for DOS 5. The reply sounds very promising. Can you see any potential problem with this solution? If not, I'm going to get the DOS 5 set of disks. Here is the reply:

Hi. I'd like to help you restore your Tandy 1000! […]
Show full quote

Hi. I'd like to help you restore your Tandy 1000!

These disks were formatted as bootable under DOS 6.22 and the utilities on the utilities disk comes from that dos version.
I do have disk image files of the 360k version of DOS 5.0 which I believe was the last version of DOS to come on 360k floppies except for "upgrade only" copies on later versions.

I can write those images (5 in total) to 360 floppies but the disks would have to be formatted under my installation of dos (6.22) which means that the boot disk will say "staring MS DOS 6.22" but then when autoexec.bat runs it'll go into the installer for DOS 5.0 that shouldn't be a problem.

I'd like to be able to test that boot-up process for you before sending you the disks but unfortunately my setup doesn't allow me to boot off 5 1/4" disks unless I were to get a different floppy drive ribbon cable which would let me hook up my 5 1/4" drive as A: rather than B:

If you want to go that route, for 5 disks and my time to write them how about the cost of 3 shareware disks ($17.85)? What I was thinking was rather than adding an "MS DOS 5.0" option to this listing or setting up a separate listing you could just buy 3 copies of "Utilities Disk" but I'll know that what you really want is the 5 MS DOS 5.0 disks.

Alternatively you could just pick up the utilities disk and that would let you partition, format, and make bootable your hard drive, but would only have very minimal dos utilities.

Incidentally the XTIDE Universal BIOS is at:

http://www.xtideuniversalbios.org

Is there any reason to opt for DOS 5 over DOS 6? I believe the eBay seller can provide DOS 6.22 on 360K FD as well as DOS 5.

Hi, sorry to hear that it din't work as hoped! 🙁
I don't meant to make things worse, but before throw the card away..:
You can try to restore the CF card to a functional state by using an old digital camera or an external picture viewer for TV set.
Or you can try to get rid of the wrong drive geometry by using a disk wiper.
Acronis True Image has such a feature, I recall. On Windows, there's SDFormatter v4, CCleaner can also wipe disks.
On DOS, there's S0KILL. There are also Linux/BSD tools you can try. Or a machine running Mac OS 9.x or OS X 10.x,
which has disk utiliy - It can create a "DOS-compatible" disk.

Tom Servo wrote:

Is there any reason to opt for DOS 5 over DOS 6? I believe the eBay seller can provide DOS 6.22 on 360K FD as well as DOS 5.

No, not really. Both MS-DOS 5 and 6.x use same kernal, which in turn is based on the DOS 3 kernal (undoing DOS 4 enhancements).
The difference in DOS 5 and DOS 6.x is rather subtly. DOS 6.2x, for example, senses "F8" key during boot (config.sys/autoexec.bat step-by-step),
whereas DOS 5 senses "F5" key only (F5 ignores autoexec.bat/config sys; DOS 6.2 does sense both F5 and F8).
DOS 6.22 also comes with more or different utilties. DOS 6.0 is closer to DOS5 in that respect.
The extra diskette no. 4 of DOS 6.22 does include these DOS 6.0 files (in English).

EdIt: I've sent you another PM, with a minimal DOS 5 boot floppy (360K).
Maybe you find a way using that on your Tandy.

Edit: If nothing works, I can send you an older, but bootable Compact Flash card via mail.
It's little in capacity, but more reliable than these used/wornout 360K floppies of mine. 😅