[HECnet] RT-11 filesystems, was Re: DECnet-RT?

[Thomas DeBellis]

How did you format the tape?  A TU55 DECtape could be formatted, but I 
thought that the cassette tapes had to be bought preformated.

On 3/31/20 5:14 PM, Clem Cole wrote:
> exactly.   You could use some COTS tapes if you carefully cut the case 
> with a box cutter to make the notch, which we as students got pretty 
> good at. IIRC Memorex worked best.  You could not use the really cheap 
> tape, but DEC used saturation recording.   The official DECcassettes 
> and compatible from the aftermarket sellers cost more than what you 
> got at the music store in Oakland.
>
> On Tue, Mar 31, 2020 at 5:04 PM Dave McGuire <mcguire at neurotica.com 
> <mailto:mcguire at neurotica.com>> wrote:
>
>
>       He's talking about DECcassette, not DECtape.  The DECcassette looks
>     like a standard Philips-style audio tape (of Walkman fame) but has a
>     notch in the top.
>
>                 -Dave
>
>     On 3/31/20 5:01 PM, Thomas DeBellis wrote:
>     > Are you referring to DECtape II?  That was a cassette.
>     >
>     > I was referring to the (nearly indestructible) earlier format:
>     simply
>     > called DECtape or DECtape I.  It's the same media as LINCtape (a
>     small
>     > reel), but with a very different controller.  These could store
>     a little
>     > over 70K (36 bit) words.
>     >
>     > On 3/31/20 4:40 PM, Clem Cole wrote:
>     >> Dave the TA11 (DEC proprietary Phillps Cassettes) were 150 ft
>     long.
>     >>  I just looked in my 1976 Peripherals Handbook -- Tape capacity of
>     >> 92,000 bytes (not kbytes mind you).   Two tapes per TA11; one
>     for the
>     >> OS and the other the user.   We had a couple at CMU on 11/20's
>     running
>     >> RT-11 in the EE Digital lab for the RT system's course - in
>     fact, the
>     >> famous "110v non-maskable interrupt" occurred on one of those
>     machines
>     >>
>     >> On Tue, Mar 31, 2020 at 3:14 PM Dave McGuire
>     <mcguire at neurotica.com <mailto:mcguire at neurotica.com>
>     >> <mailto:mcguire at neurotica.com <mailto:mcguire at neurotica.com>>>
>     wrote:
>     >>
>     >>     On 3/31/20 2:33 PM, Thomas DeBellis wrote:
>     >>     > 32MB really was ginormous back in the day; our labs had RT on
>     >>     RK05's,
>     >>     > which held about 2.5MB.  Way more than a DECtape.
>     >>
>     >>       When I started out, I had it on RL01s.  But I suspect you
>     have a few
>     >>     years on me. ;)  That was quite a bit of space at the time.
>     >>
>     >>                 -Dave
>     >>
>     >>     --
>     >>     Dave McGuire, AK4HZ
>     >>     New Kensington, PA
>     >>
>
>
>     -- 
>     Dave McGuire, AK4HZ
>     New Kensington, PA
>
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