John is correct about the 5 Volt logic control signals. The prime power is
+28 VDC spacecraft power. They have in-rush current limiters on the prime
power input and will run down to + 24 VDC and up to +32 VDC ( there is a
pre-regulator up front ). These are linear scan units ( not helical scan
like a VCR ). Sounds like you have the MMU ( Mass Memory Unit, the smaller
one ) and not the STR ( Standard Tape Recorder, the big guy ). These units
( MMU ) were digital only, and were used to download programs to the five
general purpose IBM computers ( configured like IBM 360s ). Part of this
function was to drive the " glass " dashboard ( CRTs) that provided info on
engines, etc. There was not enough room for all the standard instruments on
the " dash " that would have been required. So you could pull-up " virtual
instruments " like they have on the Toyota Prius dashboard. The two tape
reels were not driven, but maintained tape tension through differential
gears connected to a " gyrator " spring that provided relatively constant
torque between the two counter rotating reels. The tape was " pulled "
through a proprietary delta drive capstan system which incorporated the read
/ write heads. Remember this thing has to survive the G-force of liftoff and
run in a micro-gravity environment.
Best regards, Steven Canning
----- Original Message -----
From: "John C. Ellingboe" <john at guntersville.net>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Saturday, September 03, 2005 7:39 PM
Subject: Re: Mass Memory Unit from Space Shuttle
"Joe R." wrote:
>
> I found a pile of these things this morning. They are made by
Odetics
> in Anaheim Ca. After I got home with them I
realized that they are for
the
> space shuttle. Does anyone know anything about
them? I THINK they use a
> tape drive inside. I haven't opened one up yet but I saw the remains of
a
> tape drive at the same place and I think it was
the guts out of one of
these.
Joe
I'm not sure about how many the shuttle used but there is one on
each solid rocket booster. The had two tape reels stacked on
top of each other. The control signals are 5V logic and power
is probably 24V DC. I try to locate a contact to get some data
in them.