On 09/07/2019 08:11 PM, Cory Heisterkamp via cctalk wrote:
Hey Guys,

I recently picked up an MDS 6401 Key-To-Tape unit in NCR guise to park next to 
my keypunches. It's been in storage for a couple decades and is in pretty 
decent shape. Even has a tape on it from when the university that had it pulled 
the plug and sent it off for surplus. Found an internal date code of 1971.

The unit does actually show signs of life, but I suspect a power supply issue. 
Does anyone have a lead on a schematic?

This here is basically what I'm working with: 
http://www.thecorememory.com/NCR_C-735_-_MDS_6401_Memories.pdf

Thanks,
Cory
Wow, MDS was a REALLY small outfit. Or. maybe there was another company in a related field with the same acronym MDS. They made some systems for accounting, order entry and such that were not computer-based. The data was stored on a 4' diameter fixed-head disk, and they had a bunch of stations that looked like fancy desk calculators. All the logic was in the stations, and was implemented with about 50 ICs and wire-wrap. But, I'm pretty sure this was made by Mohawk Digital Sciences.

I got a Pertec key to tape system on the surplus market in about 1981 or so. It had a little core memory, a keyboard and a panel of lights so you could step through a record and view the characters. It came from the surplus outfit with schematics. I found the right place to break into the logic and interfaced it to my Z-80 CP/M system. I used it for backup. (I added a Memorex SASI-bus 8" hard drive to the CP/M system, and didn't really trust the reliability of floppies, so mag tape was a good thing to use.)

Jon

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