The Micropolis 1203 has an epoxy encapsulated 16 pin (IIRC) plug that had jumpers in it that controlled low-level things like sector size and header information and some aspects of the transfers to the host. I believe that Tek used some non-standard settings in this plug for the 85xx MDP systems. Years ago I had a couple of these drives and wanted to make them work with a homebrew system that I had built. I had no success in making them work until I stumbled across some data on the drives on microfiche aperture cards at Tek that documented the nature of what was inside this encapsulated jumper block. Once I had this information, I was able to build a DIP header with jumpers in it that allowed me to make the drives work the way that the generic drive docs said they should work. It appears that Tek had ordered the drives in a non-standard configuration to lock folks into using Tek service and replacement drives. This could be why ex-8560 drives do not want to play nice with other computers like the PERQ. Sadly all of was many years ago and the specifics are long gone from my memory and the prints that I.got out of the aperture card readers that had the data about the plug were long ago thrown out. But, I figured that I would mention it here in that it may trigger more detailed information in someone's memory. Rick Bensene -----Original Message----- From: Al Kossow [aek at bitsavers.org] Received: Friday, 31 Aug 2012, 2:42pm To: cctalk at classiccmp.org [cctalk at classiccmp.org] Subject: Micropolis 1203 Re: Reviving a PERQ 1a On 8/31/12 11:42 AM, Tony Duell wrote: It is a 1203. I guess we need to keep an eye out for the 1203 manual, since it sounds like you don't have a copy either. I will probably need this at some point to try to figure out why the 12xx series drives out of the Tek 8550 aren't working. I'll have to look in my email to see if I can find the PAL equations you sent. Sometimes things get forgotten if I get busy dealing with other things.