Tony and Sellam, thanks to both of you for the suggestions. I'm going to give Sellam's idea a try first since it's easier to poke a few keys than to open the box ;>) I'll let you know what I find out. The H89 was just one of several computers I've been given recently. Among them were several TS1000s, a ZX80, a TS1500, an Apple ][e with monitor, dual drives, and printer, and more. The CP/M boxes alone include the H89, two Z100s (one with hard drive!), and a Xerox 820 with hard drive and dual 8" drives. As I bring these boxes into action I'm sure I'll have plenty of questions for the CP/M folks out there, and some for the Z80 and S-100 hardware people too ;>) For starters: The Z100 with the hard drive looks good, but I can't format the ZDOS partition. PREP initializes the drive, tests the media (this takes 1.5 hours on a 20 MB drive), and creates the partitions. I can then monkey around with the size of the partitions and their names, etc. However, FORMAT E: /S produces "Invalid media type reading drive E: Abort, retry or fail?" I've swapped three different hard drives into the system, and replaced the hd controller (I don't think I have a spare data separator board). I can successfully initialize and copy files to the CP/M-85 partition (can't make it bootable yet as I don't have complete CP/M-85 system disks for it). And, what are the four adjacent jumpers on the hd controller (not the Format Enable)? Is there any documentation available for this board? I have docs for all the Z100 hardware except the hd controller . . . Any ideas are welcome! Glen 0/0