Paul Thanks, I had found this ad a while ago but thought it was ¼-inch. Upon careful reading all the notes I found, "Errors per roll based on recording 7 tracks on rolls ½" x 2500'. "
It looks like 3M may have called their computer tapes "Instrumentation" tape until the late 60s Tom -----Original Message----- From: Paul Koning [mailto:paulkon...@comcast.net] Sent: Thursday, June 25, 2020 5:15 PM To: Chuck Guzis; cctalk@classiccmp.org Subject: Re: Early 3M Computer Tape Type Numbers > On Jun 25, 2020, at 5:14 PM, Chuck Guzis via cctalk <cctalk@classiccmp.org> > wrote: > > On 6/25/20 1:55 PM, Tom Gardner via cctalk wrote: >> I'm trying to figure out what were the earliest Type numbers for 3M >> -inch reel-to-reel computer tape >> >> As best I can find, 3M began marketing a Type 777 computer tape about 1967. >> The Type 700 appears to be somewhat later. But 3M sold computer tape >> directly to at least government customers (e.g. NSA, Social Security) in the >> 1950s. The also notably OEMed tape to IBM who rebranded it under an IBM >> label until the late 1960s at which point with the help of Sony IBM began >> manufacturing its own computer tape. >> >> Anyone have any idea of the Type number for 3M computer tapes earlier than >> Type 777? >> >> There might be a place for some of these older Types at the CHM if anyone >> knows of any still in existence. >> >> Tom >> >> PS: There is a lot of information on 3M audio tape Type numbers as >> at http://www.aes.org/aeshc/docs/3mtape/aorprod-cust.pdf but computer >> tape seems to be an orphan > I probably do--but I'm going to have to look through my logs. Old 3M > tape is terrible for binder that sticks to everything. Before > processing the stuff, I have to lubricate it. Except for DECtape, of course. That's 3M 340 or 341, the spec (from Nov 1966) is here: http://www.bitsavers.org/pdf/dec/dectape/3M_DECtape_Spec_Nov66.pdf paul
