Re: [escepticos] reminiscencias OFFTOPIC

[Tei <421621@xxxxxxxxxxxxxxx>]

hummm 

fe de erratas de un mensaje anterior

el voyager no tenia el z80 de chip

(parece que se me fue la mano :P )

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What kind of computers are used on the Voyager spacecraft?

There are three different computer types on the Voyager spacecraft and
there are two of each kind. Total number of words among the six
computers is about 32K.

Computer Command System (CCS) - 18-bit word, interrupt type processors
(2) with 4096 words each of plated wire, non-volatile memory.

Flight Data System (FDS) - 16-bit word machine (2) with modular memories
and 8198 words each

Attitude and Articulation Control System (AACS) - 16-bit word machines
(2) with 4096 words each.

According to my calulations, that's a total of about 541KB, or small
potatoes compared to today's microprocessors. We probably could perform
all functions with one of today's boards and still have room for solid
state data storage and much more fault detection software. We would
still need a second unit for redundancy. Today's microprocessors are
also much faster than the 1802 derivatives used on Voyager and a
comparative system would use less electrical power. On the other hand,
software might be more complicated as opposed to that used in an
interrupt type system, but it would be much more capable and more
flexible.

Let's look closer at the CCS. The CCS has two main functions: to carry
out instructions from the ground to operate the spacecraft, and to be
alert for a problem or malfunction and respond to it. Two identical
4096- word memories contain both fixed routines (about 2800 words) and a
variable section (about 1290 words) for changing science sequences. The
CCS issues commands to the AACS for movement of the scan platform or
spacecraft maneuvers; to the FDS for changes in instrument
configurations or telemetry rates and to numerous other subsystems
within the spacecraft for specific actions. Fault-protection algorithms
are also stored in the CCS, occupying roughly 10 percent of the CCS
memory.

The main functions of the FDS are to collect data from, and controls the
operations of, the scientific instruments; and to format engineering and
science data for on-board storage and/or real-time transmission. The FDS
also keeps the spacecraft "time" and provides frequency references to
the instruments and other spacecraft subsystems.

The Voyager spacecraft computers are interrupt driven computer, similar
to processors used in general purpose computers with a few special
instructions for increased efficiency. The programming is a form of
assembly language.

There is no clock chip, as such, in the spacecraft. The "clock" is
really a counter, based on one of several electronically generated
frequencies. These frequencies, based on a reference, generated by a
very stable oscillator, are converted and fed to different locations in
the spacecraft as synchronization signals, timers, counters, etc. The
"clock" signal is part of the information telemetered to the ground and
it is with ground software that we convert to day of year, time of day
Greenwich Mean Time.

Voyager was built in-house at JPL; the computers were manufactured by
General Electric to JPL specifications.