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[DPRG] Shuttle computer question

Subject: [DPRG] Shuttle computer question
From: Daryl Gallatin dgall723 at mail.dal.devry.edu
Date: Tue Feb 11 15:27:00 CST 2003

How did they fit an IBM 360 into the shuttle?

I thought DEC made the Alpha in the 1980's

The history page says they use HAL/S to program the the cpu.


Thanks for the info
>>> "Earl Bollinger" <earlwbollinger at attbi.com> 02/08/03 08:12 AM >>>
And the winner is the venerable IBM 4Pi AP-1 360 mainframe based discreet
component CPU system.
Core memory, redundant tape storage (no hard disks drives).
All programs were written using assembler language, no higher level
languages used.
Just think, millions of lines of assembler code, if you were one of the
programmers, you'd be set for life, they could never lay you off, unless the
whole program went belly up.

Computer History stuff:

Skylab, using predecessor to Space Shuttle computers.

Space Shuttle:

Quoted from NASA history articles:

Unlike Gemini and Apollo, NASA wanted an off-the-shelf computer system for
the Shuttle. If "Space rating" a system involved a stricter set of
requirements than a military standard22, starting with a military-rated
computer made the next step in the certification process a lot cheaper. Five
systems were actively considered in the early 1970s: The IBM 4Pi AP-1, the
Autonetics D232, the Control Data Corporation Alpha, the Raytheon RAC-251,
and the Honeywell HDC-70123. The basic profile of the computer system
evolved to the point where expectations included 32-bit word size for
accurate calculations, at least 64K of memory, and microprogramming
capability24. Micropograms are called firmware and contain control programs
otherwise realized as hardware. Firmware can be changed to match evolving
requirements or circumstances. Thus, a computer could be adapted to a number
of functions by revising its instruction set through microcoding.

Despite the fact that Draper Laboratory favored the Autonetics machine, and
a NASA engineer estimated that the load on the Shuttle computers would "be
heavier than the 4Pi [could] support," the IBM machine was still chosen25.
The 4Pi AP-1's advantages lay in its history and architecture. Already used
in aircraft applications, it was also related to the 4Pi computers on
Skylab, which were members of the same architectural family as the IBM
System 360 mainframe series. Since the instruction set for the AP-1 and 360
were very similar, experienced 360 programmers would need little retraining.
Additionally, a number of software development tools existed for the AP- l
on the 360. As in the other spacecraft computers, no compilers or other
program development tools would be carried on-board. All flight programs
were developed and tested in ground-based systems, with the binary object
code of the programs loaded into the flight computer. Simulators and
assemblers for the AP-1 ran on the 360, which could be used to produce code
for the target machine. In both the Gemini and Apollo programs, such tools
had to be developed from scratch and were expensive

-----Original Message-----
>From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf
Of Earl Bollinger
Sent: Saturday, February 08, 2003 7:42 AM
To: dprg
Subject: RE: [DPRG] Shuttle computer question

Actually, the last I remembered, they were "old" mainframe like 360 based or
minicomputer based computers using magnetc core memory.
Very radiation hardened. What they used was computers able to withstand a
lot of irionizing radiation.
No Intel CPU's in the system.
Although maybe RCA 1802's or the old Harris PDP-8 CMOS CPU's may be
sprinkled aout.
Remember you have to think 1970's technology for 1970-1980 design Shuttles.
The Intel 4004 hadn't come out yet, much less any more modern CPU.

-----Original Message-----
>From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf
Of Sluggy
Sent: Tuesday, February 04, 2003 11:50 PM
To: dprg
Subject: Re: [DPRG] Shuttle computer question

Rodent wrote:

> As far as I have heard, this is true. Maybe they got spooked with the
> Pentium (ie 587) and stuck with what works? Most of their computing
> are supposed to be at least triple-redundant as well.
> ----- Original Message -----
> > I've heard that the processors on the space shuttles are or were 386 or
> 486 processors?
> > Can't seem to find anything to confirm this. DOes anyone here know?

I don't know about that, but it wouldn't surprise me. The name of the
game is Reliability, with a capital "R". A late generation 386 has had
most of the bugs designed out and most of the rest have been discovered
and can be compensated for. No surprises in operation.

The Mars Sojourner had an 8031 variant on board.



This bounty hunter is my kind of scum: fearless and inventive.

                            Jabba The Hutt

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