Voyager 1 FDS Computer Emulator | Hacker News Reader

Voyager 1 FDS Computer Emulator

zaneham.github.io

92 pointsrahen17 comments

The author has also published a Setun-70 emulator (a Soviet ternary computer rather than a binary one):

https://github.com/Zaneham/setun70-emulator

I was just looking at this yesterday. Apparently Voyager 1 architecture, ISA, etc are well known but Voyager 2 is still denied via FOIA on grounds of copyright.

Would they be different? They launched 16 days apart. I always assumed they were mostly the same core hardware. hm... rereading the wikipedia pages now...

Voyager 1 and Voyager 2 are identical, as are their computers. JPL's Voyager documentation is the property of Caltech, not NASA, and are thus not available via FOIA. People have gotten copies of selected documentation by requesting them from libraries that have copies of the original documents on file.

Are the distance and signal delay numbers supposed to be accurate? NASA's page has them substantially different. Nice work, however!

https://science.nasa.gov/mission/voyager/where-are-voyager-1...

Next add realistic signal delay so you have to wait a day to get the result

Is it possible to hook this up to some kind of satellite space simulator to control a virtual voyager?

Wow. Only 10 instruction set? Looks like father of RISC cpu design

This was common back then. The PDP-8 had eight primary instructions, although one of them was multi-purpose. This helped keep the hardware simple when we didn't have ICs.

RISC isn't about having a small ISA but about a regular, orthogonal instruction set.

The FDS CPU is very RISCy in nature, but it actually has close to 40 instructions! https://forum.nasaspaceflight.com/index.php?topic=9476.msg26...

And it has been compared to the PDP-8 like rahen suggests, although the Voyager computers are built from medium-scale ICs!

it would be amazing to include a few example programs!

Click the "Load Example" drop-down menu in the bottom-right corner.

- stupid question: what is the program about? what are we trying to achieve?

It emulates the computer that runs Voyager 1.

I'm not sure I understand the question.

but how did you get access to the actual program that NASA has running on it?

It's not my project but presumably someone has a copy.

They didn't get access to the actual NASA software running in space. They wrote simple example programs to exercise the CPU emulator. The example program that is loaded when you first visit the web page simply counts down from 10.

And having the actual NASA source code would not be very useful, since the actual software interacts with complex hardware on the spacecraft, which you would have to emulate in addition to just the CPU. For example, the FDS computer interacts with all of the scientific instruments, the digital tape recorder, the telemetry output hardware, and the other two computer types on the spacecraft. (I'm not casting shade on the CPU emulator as it is an impressive achievement and the code is very high quality.)

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