Here are several web sites that you may find interesting or helpful:
S-100 Computers is a website by John Monahan that is devoted to users of S-100 bus computers and concentrates on the CP/M family of operating systems. His most recent work is development of an IDE Controller for use with CP/M. If you use CP/M you may wish to check this out. When he has completed his work, we are hoping he will also help us with the Z-100's CP/M operating systems.
The Heathkit Museum was a virtual tour of many Heathkit products, but I have not been able to find this site up in quite a while. Before the demise of the @home web server, I seem to recall there was a much more extensive line-up of products described, but it is mostly radios now. I hope this expands again to include computers. I'm also disappointed because I could find no way to contact them.
The Old-Computer Museum is a French web site (but in English) developed by Thierry Schembri and Olivier Boisseau. The site provides information on over 700 old computer systems from around the world, including the H/Z-89 and H/Z-100. Use the search window to locate the computer you desire information about.
Bill Wilkinson's Site describes his experiences with the Heath Company. A former electronics technician, he also includes troubleshooting help with separate sections for the H-19 and H-89 terminals.
Gene Buckle's Site provides an interesting step into the past, discussing numerous subjects about all the early Heathkit computers, including the H-8, H-89/90, and the H-100. He also provides an on-line copy of the first issue of "The Staunch 8/89'er", a newsletter for the H-8 and H-89 written by Kirk Thompson and later, Hank Lotz.
Herb Johnson's S-100 Site and Herb Johnson's Zenith Site and Herb Johnson's Z-100 Repair Site
Herb Johnson's S-100 Site provides a source of information regarding the S-100 bus computers, of which the H/Z-100 was one. Herb Johnson's Zenith Site provides an important remaining source of Zenith software, manuals, and parts. And, his latest, Herb Johnson's Z-100 Repair Site offers another important source of Z-100 repair information. You may also recall that Herb wrote a series of articles about the S-100 Bus for "The Computer Journal" in the 1990s as "Dr. S-100".
Harte Technologies provides an interesting site with manuals to a number of Heath/Zenith Computers, including the H/Z-89/90 series and the H/Z-100 series computers. For Z-100 specific documentation, add "Z-100/" at the end of the URL. This is a work in progress, but if you need a .pdf version of the Technical or Service Manual, this is the place to go. Be aware that these are LARGE documents and take awhile to download. The H/Z-100 schematics will be added in the near future. My thanks to Howard Harte, Barry Watzman, and the others who helped with this project.