View Full Version : Toshiba T250

July 24th, 2017, 07:35 AM
I've come into possession of a Toshiba T250. Machine was complete (but very dirty) and came with a couple boxes of 8" media (that may be mixed in with media for another board - an Advanced Micro Digital "Super-Quad").

After an inspection internally and some voltage checking, upon power up the machine comes up with a beep and the message "Mount System Disk" in the center of the screen.

So - I need to see if any of the media I have goes with the machine, and then get a sense if any of it might be in good enough shape to try and read.

This link talks primarily about the T200, but has a mention of the T250

It looks like the Maslin archive has a copy of CP/M for the Toshiba T200. I'm guessing that I can't image that onto an 8" disk...

If anyone has further experience with the T250, disk images or same, or a clue for the clueless (me) on how to perhaps generate a usable OS image I'm all ears.

I'll post up more about the "Super-Quad" when I dig through that stuff a little more.


July 24th, 2017, 10:51 AM
It looks like the Maslin archive has a copy of CP/M for the Toshiba T200. I'm guessing that I can't image that onto an 8" disk...

Yes you can!

You need a DOS era PC (the FDC chip is the key) and one of these: https://github.com/NF6X/fd50to34

Which you can get from OSH Park here: https://oshpark.com/shared_projects/Hr1FTWxB

Alternatively.. you can use the little fd50to34 board to connect a floppy drive emulator (such as an HxC device like this one: http://hxc2001.free.fr/floppy_drive_emulator/ which you can buy here: http://www.lotharek.pl/product.php?pid=18 ) and put the image on the SD card, configure the Toshiba's 8" drive as B: and the emulator as A:, then boot, format a fresh 8" floppy and transfer CP/M across.

I am sure there are other approaches but I have used both successfully on a TRS-80 Model II (which has a single 8" drive).

I also followed this set of instructions (http://nemesis.lonestar.org/computers/tandy/hardware/model16_6000/floppyfix.html) to make up a 50 to 34 way floppy cable (before I bought the fd50to34 adapter) and it worked. I plugged one end into my PC, the other into the 8" drive (still in the TRS-80 chassis, and powered by the TRS-80 PSU), and used a program called IMAGEDISK written by Dave Dunfield (http://www.classiccmp.org/dunfield/img/index.htm) to write an image directly to an 8" floppy.


July 24th, 2017, 12:20 PM

Thanks for this info! Seems like this takes care of the "plumbing" of getting the 8" drive hooked up to a more modern PC.

Forgive me since I'm fairly unfamiliar with CP/M, but my 2 part question is whether the image for the T200, which is a machine with 5 1/4 inch drives, will work with the T250, which is 8" drive. Part 1 is whether the image will even be correct on the drive because of the different size and formatting. Would these translator boards be able to cover for that? Seems like it wouldn't. The second question would be whether the CP/M for the T200 would work with the T250, since I know that CP/M builds are generally fairly machine specific.

Thanks for any info...


July 24th, 2017, 10:53 PM
You can try it.

However, your point about CP/M builds is correct. Parts of CP/M (CCP, BDOS) were standard, but each machine had its own BIOS to allow the BDOS to talk to the machine's hardware. Crucially, DRI didn't mandate a specific disk format, so disks were not interchangeable between machines.

Having said that, it is still worth attempting. It won't cost much except for time, and it's a hobby. The board is an electrical interface adapter, and won't change the disk format. On the other hand, you could attempt to connect a 5.25" drive to the machine and boot from that.

Can't find much info on it. There's one for sale though: http://www.ebay.com/itm/Toshiba-250-CP-M-SYS0037B-w-8-disk-drives-/282520939138

July 25th, 2017, 07:12 AM
I agree there's not much to lose to give it a try. The journey is the reward, right? :)

Say that hypothetically I got the T250 to boot from the T200 disk image off a 5/25 disk. If I left the second 8" drive in the machine, do you think a SYSGEN from the 5.25" to the 8" has a chance of creating a bootable 8 disk? I suppose that would depend on whether the T200 BIOS supports the 8" drive...

The machine you linked is in fact the machine I have, bought through a contact here in the Twin Cities. Rest assured I did not pay that much for it, and I also got some Televideo terminals (970 and 925) and other goodies as well. I'll let him know to take the eBay listing down.

July 25th, 2017, 08:25 AM
The format for the T250 is very different from the T200. For example, the T250 uses a double-sided 8" floppy with 26 sectors of 256 bytes per track (52 per cylinder). The T200 is a 5.25" format using 16 sectors of 256 bytes per track (32 per cylinder). The DPB, etc. are completely different. I doubt that you'll be successful.

I may have a T250 sample in my mengaerie. If it's got a system, I'll image it and post the image.

July 25th, 2017, 08:45 AM
I think Chuck is saying that sysgenning a 5.25" boot disk to the 8" drive won't work, and I agree.

But maybe you can boot off a 5.25" drive and carry on using that for now? Effectively convert your T250 into a single drive T200? If the hardware is the same (other then the 8" drive), it might just work. You have very little to lose here - and besides, you're going to need a 50 to 34 way adapter either way.

July 25th, 2017, 09:02 AM
Here's the T250 Boot that I have (https://app.box.com/s/zouvshz34esgl3v6r6swo2tf4serfoav).

Please note that I won't leave it there for long, so get it while it's hot!

July 25th, 2017, 10:23 AM
Here's the T250 Boot that I have (https://app.box.com/s/zouvshz34esgl3v6r6swo2tf4serfoav).

Please note that I won't leave it there for long, so get it while it's hot!

Chuck(G) - got it - thanks! I figured if I was going to find a disk image for this guy anywhere, it would be here.

I assumed the media and format differences would not allow a SYSGEN from one to the other to be successful, but it was worth it to ask.

Now I just need to get the electrical plumbing figured out, but that looks more like a problem of execution than invention.

Thanks to both of you for your help!

July 25th, 2017, 10:36 AM
No problem--I have a very large menagerie of samples--much of it dates from the time when Don Maslin and I would swap samples. Mostly, I don't know exactly what I've got until I actually go and look.

Lots of systems never mentioned here in the time I've been a forum member.