[COFF] How much Fortran?

[Michael Kjörling]

On 3 Feb 2020 12:06 -0500, from crossd at gmail.com (Dan Cross):
> Regardless, one DOES wonder in what capacity FORTRAN was used in the
> mission. Was it used on the onboard computers, or was it used on the
> downlink stations for e.g. data analysis?

I would be _extremely_ surprised if the Voyager probes themselves run
FORTRAN code.

Maybe, possibly, just barely _might_, they run code that was compiled
from FORTRAN code, but that seems unlikely.

Somewhat less unrealistically, they might run software which was
initially prototyped in FORTRAN, before being translated into
something else. But even that seems a stretch.

Adding up the numbers in [1], the memory capacity of each of the
Voyager probes comes out to a total of 557,248 bits (not bytes), split
between custom-built computers with 16 and 18 bit word lengths.
Wikipedia summarizes it as "Total number of words among the six
computers is about 32K." which seems about right; 557,248/17 ~ 32,779,
and two out of the three computer pairs are said to use 18-bit words.

For ground data processing systems to run code written in FORTRAN does
however seem plausible to me.

 [1] https://en.wikipedia.org/wiki/Voyager_program#Computers_and_data_processing

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Michael Kjörling • https://michael.kjorling.se • michael at kjorling.se
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