Mass Memory Unit from Space Shuttle

[Steven Canning]

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.