IDE Project Card
With IDE the controller is part of the hard disk. What was needed was to design an adapter to make the PE-box bus look like a PC bus. It would be easier except TI multiplexed the TMS9900 16-bit bus to 2 times 8 bits so there was a need for a demultiplexer.
This interface card supports two IDE drives.
There is also a 32K to 512K SRAM memory chip on the card. It serves to hold the DSRs and the buffers for opened files. The memory is also available to the user in the area >6000-7FFF, according to the RAMBO protocol introduced with the Horizon Ramdisk.
Also on board is a real-time clock. This allows the software to time-stamp the files.
Originally the clock chip also contained 4K of battery-backed memory, so there sat the DSRs, to be transfered in the SRAM at power-up time. Unfortunately, this chip is now very hard to find. Thus, the new version of the card accepts four different clock chips.
Apart for supporting 4 different clock chips, the second version card features the 74F543-based demultiplexer, which should make it compatible with Myarc's Geneve. It also has DMA capability.
The card is not marketed but Thierry's web site has all the necessary instructions. The printed circuit is available on the site in Gerber format read to send to any commercial venture. The operating system and manual are also available on the site to download.
What hard drives
The IDE bus is intended for two devices: a master and a slave. These could be hard-drives, or a CompactFlash based drive. The card has been tested with a single hard-drive, but it should also work with two. Just make sure you place the jumpers properly on each drive.
Your drive must be recent enough to support LBA (logical block addressing). This is purely a software requirement: that's what the DSRs are expecting. Of course, if you are willing to write CSH addressing routines yourself, feel free to do so. The maximum supported size is 128 Gigabytes per drive.
Moved from the faq:
I need the latest DSR for the IDE board, where can I get it?
There are actually two DSR available for board. One you will find on Thierry's TI Tech Pages and is the original DSR developed for the board. The second one is from Fred Kaal and it has some great features you may want to look at. 
Can I load an IDE drive on a PC with information from disk images (V9T9, PC99) and then move it to the TI with an IDE controller for use?
I don't believe a tool or program exists to do this. This is speculation here but in order to do this one of the following must ocurr:
1) There must be a program written on the PC that understands PC99/V9T9 images and a driver that supports the TI formatted version of an IDE drive (essentially a PC equivalent of the DSR).
2) One of the emulators must be aware and be able to use a TI formated version of an IDE drive which would still require a driver to be written.
So from those two possibilities the need for a driver (DSR like program) for the PC to understand and to be able to work with a TI formated IDE is requried. Also, the driver would have to either work with an TI IDE system based on Thierry's DSR and/or Fred Kaal's DSR. All in all this is a big effort.
With Fred Kaal's DSR how many directories off of the root directory are supported
Also how many in each subdirectory are supported?
Fred's DSR supports 127 files per directory and 114 subdirectories.
Where can I get an IDE card?
The IDE was a project card where various people joined together and had did a group buy to get lower prices on the parts.
The schematics and files for the board are available on Thierry's TI Tech pages.
In addition to that there is a list of parts needed. If you are skilled in soldering (small parts, surface mount chips, etc) then you could build one on your own. Otherwise you would need to have someone build it for you. Prior to doing this you might want to ask if anyone has a spare board they'd like to part with on the Yahoo mailing list.