The List!

On Thu, 1 May 1997, Bill Whitson wrote: To add to his list, fill in blanks: Z-89 CP/M Z-90 CP/M Z-100 192K/768K CP/M & Z-DOS Heath Corporation------------------------------------------------- H-89 Z80 48K CP/M Micro 79 H-90 (?) H-100 8088 w/8085 192K/ CP/M & Z-DOS Micro 81 768K The Heath Corp. computers (Heathkit) actually preceded the Zenith computers, although they are basically the same computer: the Heath version is the kit form, and the Zenith version is the factory assembled form. Heath originally designed them, then Zenith acquired Heath. I think the H/Z-100 was the first they worked together on. The Heath/Zenith H/Z-100 is a dual-operating system computer, running both CP/M and Z-DOS (Zenith DOS), then later Zenith-modified MS-DOS. The CP/M runs on the 8085, and the MS-DOS/Z-DOS boots up on the 8085, then switches to running on the 8088. Other OS available were CCP/M, CP/M-86, MMP/M (very brief), and I think that there was also a version of Xenix available, although I'm not positive about that. Seems to me it was also possible to get the Pick OS, but again, my memory is hazy as to that. At any rate, neither was the main OS if they were available. Once the 41256 RAM chip became available, the H/Z-100 had a maximum of motherboard RAM of 768K (became available from Heath/Zenith in 1985, I think). It's capable of addressing 16 Meg if someone wanted to put it in, although they would have to write their own software to manage it. Currently, the H/Z-100 can run 8", 5 1/4" (40 & 96 tpi), and 3 1/2" (96 & 135 tpi) floppy disk drives; MFM hard drives (also RLL, although not common), tape drives, and SCSI drives. CD-ROM drives are also possible. It was designed to run both 8- and 16-bit software, so people who had a big investment in 8-bit software running under CP/M would be more willing to buy a new computer. That dual OS design sold the military on the computer, and Zenith made a bundle on military contracts for it. Original operating speed was 5 Mhz; Heath/Zenith later upped that to 8 MHz. A common modification allows it to run at either 8 or 10 MHz. Someone has also managed to get it running at 33 MHz. However, it is not PC-compatible due to the S-100 buss design and the video. You can run a great deal of PC software on it, although the code may need patching in order to do so. Hope this adds to your computer list & provides interesting information. Susan