Pietja successfully built and tested our CPLD-based XT-IDE adapter v2. These boards give old XT PCs the ability to interface with IDE hard-drives and compact flash cards. There are still lots of these old boxes out there running medical and industrial equipment, and the XT-IDE cards keep them going with modern drives.
The Vintage Computer Forum’s original XT-IDE design uses discrete logic chips and all through-hole parts. Our version puts all the chips into an XC9572XL CoolRunner-II programmable logic CPLD. We design the controller logic in software, compile it, and upload into the CPLD.
Occasionally someone finds a small hardware hack that increases XT-IDE performance. “Chuck MOD” rewires a few traces to get a considerable speed boost for example. On the original hardware this was done by cutting and rerouting a trace with a jumper wire. We just upload a new design with the changes into the CPLD.
Our v1, 1va, 1vb XT-IDE hardware only combined a few of the logic chips into the CPLD. After testing the concept though, we moved to a 100% CPLD-based design in v2. It’s a blank canvas with an EEPROM chip that can be a disk controller, or something completely different.
The very first revision of the v2 hardware works perfectly so far.
Here’s a performance benchmark using the stock BIOS and logic:
- Write Speed : 214,06 KB/s
- Read Speed : 243,11 KB/s
- 8K random, 70% read : 21,15 IOPS
- Sector random read : 65,05 IOPS
- Average seek, including latency, is 15,67 ms.
The XT-IDE adapter with CPLD v2a source package includes the latest hardware files and Pietja’s bitstreams for v2 and v1 adapters. We have a couple of free PCBs available to vintage hardware maintainers. Join the hacking in the forum.
A big thanks to Pietja, J1mbo, and alanh for help developing and testing the hardware. A huge thanks to members of the Vintage Computer Forums for their original design and the XTIDE universal BIOS drivers that make our hardware possible.