View Full Version : Ti-99 Disk Drives

May 9th, 2008, 03:30 PM
Will the original TI Disk Controller work with a DS/DD Floppy Drive if you use only DS/SD or SS/SS Floppy Disks?


May 11th, 2008, 07:34 AM
Define original TI Disk Controller: the external one that was a sidecar peripheral or the card for the expansion box?

The sidecar controller works with single sided, 40-track drives. It won't recognize the second side. It formats them as SSSD, no matter what the capacity of the hardware or the disk is (90K). I have one of these.

The TI card for the PEB works with double sided drives and disks--but it will only format them as single density (SSSD or DSSD==90K or 180K). There is a modification to the DSR to allow them to work with 80-track disks and drives, which doubles the capacity but the mod is not common. I have two of these--neither with the mod.

If you are really lucky, you may eventually track down a TI Double Density Disk Controller--it is set up to allow 40-track DSDD drives. It formats them at 160K or 320K (somewhat nonstandard, as the Myarc controllers are the only other TI cards that read it well). I own a pair of these, one of which I assembled myself. TI never sold them outside their engineering staff--and they were provided as a build-it-yourself kit. Somewhere between 30 and 40 of them are known to exist.

Atronic (in Germany) produced a DSDD card for a while, very similar to the CorComp. I have one of these, and there are 20 or so more of them still in collector hands. They also produced a sidecar expansion known as the CPS99 which included 32K memory, RS232, Disk Controller, and 2 half-height drives in a single case. I don't have one of these.

CorComp made several variations of their DSDD card. I have one of each of the three major variants. CorComp also built a Micro Expansion device that plugged into the side of the console. It came in several variants, the most complete one containing 32K, RS232, and a Disk Controller. The 32K and RS232 variants were available separately and even combined. I don't have any of these except the stand-alone 32K memory.

Myarc made several disk controllers as well: A floppy controller that was a TI DSDD workalike, later modified to allow the 360K CorComp format and then modified to allow DSDD 80-track drives. They also built a Personality Card to allow connection of SASI hard disks up to 15MB, and a Hard and Floppy controller card that allowed 80-track DSDD floppies and up to 80MB MFM hard disks. When used on a Geneve 9640, the some HFDC cards can be used with 1.44MB floppy drives as well. I have one of each of the cards noted here. Myarc also built a side-car device called the MPES50, which included 128K memory, RS232, Disk Controller, and 2 Half-height drives. I don't have one of these.

Percom also made a DSSD sidecar disk drive that put both drive and controller in the same case. I have one of these too.

The System 99 User Group (SNUG) made about 120 examples of a really nice floppy controller in Germany--it was also a CorComp workalike and worked for anything up to DSDD. I have one of these from the first production series (the first 80 boards were series 1).

Thierry Nouspikel designed a nice IDE interface board for drives up to 240MB (they can be larger, the extra space won't be recognized though). About 100 kits were sold to hobbyists to build themselves. I have one of them that I still need to assemble.

WHTech built several revisions of a SCSI I controller for the TI. Michael Becker of SNUG designed several improvements to it and provided them to WHTech in exchange for the right to make his own derivative cards (known as the ASCSI card). I have two of the ASCSI cards and none of the WHTech variants.

This is an almost complete list of disk controllers developed for the TI. I say almost complete because there was a card developed in Australia for their home-grown mini expansion box that I've never seen. It was supposed to be a CorComp workalike as well. These were all built by hobbyists and exist in very small numbers (a dozen or two). So far as I know, none of them ever made it to the US.

Most of this information and a lot more is available on Ninerpedia, placed there by me and several other diligent people trying to ensure that detailed knowledge of things TI survive.


June 2nd, 2008, 10:00 PM
I found out that there are only 2 cards that will work correctly with the DSDD drives.

I am now in the quest for 5.25 Floppy Disks and the shipping costs on Ebay almost make it not worth it. Does anyone now any other sources besides ebay for the Floppy Disks?

June 4th, 2008, 06:20 PM
The following cards work as DSDD controllers:

1. TI DSDD (rare, as they were all engineering prototypes)
2. CorComp
3. Atronic
4. Myarc FDC (two versions of the DSR--one for 40-track and one for 40 or 80-track drives, all DSDD)
5. Myarc HFDC (works with 40 or 80 track drives, and also MFM hard disks)
6. BwG

All but 1 and 3 are relatively common. The Myarc FDC is also part of the MPES- 50 expansion sidecar, the CorComp is also part of the 9900 sidecar, and the Atronic is part of the Mechatronics CPS-99 sidecar (the only common version of the Atronic controller).

Disks can still be purchased new from several sources in 100 to 1000 piece lots. E-bay has them but as you noted, they kill you on the shipping.

June 29th, 2008, 02:33 PM
I found out that there are only 2 cards that will work correctly with the DSDD drives.

I am now in the quest for 5.25 Floppy Disks

You might consider 3" drives...