Our magnificent IBM 729 7-track magnetic tape drive is giving us read and write errors. We attempt another heroic repair. Which is a great excuse to take a close look at its amazing innards. Looks like nothing in the video, but just putting the 3 brush blocks back was a 3 hour operation with mostly 6 hands at a time inside the drives – including mine, which is why there is no video documenting it. Hence the clapping at the end, we were quite relieved we did put it back together correctly!
Tape capacity is around 20 MB at the highest (800 cpi) density setting. Actually quite respectable if you compare it to this machine’s main memory (16KB).
Special thanks to Samtec for fabricating and donating the IBM-spec special wire. Extra special thanks to Shashi Chuganey for spooling the wire from scratch at our Oregon facility, and to Raymond Lee for silver epoxying them in our clean room facility in California. Also thanks to CHM docent team member Dave Bennett for finding a commercial source of replica brushes. So I didn’t have to do the 92 production ones after the first 8 hero prototypes…
Many more people were involved in getting these tapes operational, but limiting ourselves to the ones that appear in this video:
Official video of our IBM 1401:
Period video introducing the IBM 1401:
Robert Garner’s blog article about the restoration:
The restoration team’s hardcore technical website:
Our sponsor for PCBs:
Support the team on Patreon:
Merch on Teespring:
Learn more on companion site:
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