Early MSC HD controller

Chuck Guzis wrote: The controller that Microdata had was modified from the controller design that ran Microdata branded drives directly, but was also all 7400 logic with a 74181 alu type cpu sequencer. I have schematics for both versions of this that hopefully will get scanned and posted on bitsavers sometime soon. Microdata's cpus were both ALU type cpus while I was there in the late 70's and the controllers all had 1 or 2 in their sequencers as well, in their disk controllers, and in their terminals. Tape and com controllers were more state machine type devices, and the printer, card reader, and paper tape read punch boards were just parallel access interfaces with the cpu doing the work. Was the back end of this controller anything resembling sasi, sequential or parallel register interface? I think the MSC controllers into the microdata minis were all serial interfaced on the back end, since the controller cabling and logic had RF serial / deserializer logic that had to remain, since they talked to both microdata drives which were serial RF as well as the MSC controllers w/o any extra connectors to go around the serial logic. you moved a jumper or two, but other than that, the MSC controller just made more heads and cylinders show up to the software, and the seeks were also passed as pulse trains, not as parallel info (like SMD). Xebec picked up and modifed the SASI interface and blessed us with a fouled up early SASI command set which survives at the heart of IDE of course. I'm not aware of a "Xebec" or "MSC" design that survived, but just as you say a lot of custom adaptations. Jim