5 ms·

I'm ready to throw our old, expensive, and fairly slow flight computers with no drivers and terrible lead time to the curb and get on board with something new.

I'm ready to throw our old, expensive, and fairly slow flight computers with no drivers and terrible lead time to the curb and get on board with something new. Especially if an open ISA means that our systems will be more portable and faster to develop.

smoldesu 4y ago
It really seems like the perfect storm. Hopefully other folks like NASA will get comfortable jumping on the RISC train now that their only option isn't licensing from ARM.
- giantrobot 4y ago
  NASA's been on the RISC train for nearly 30 years. They've been using the RAD750 since the turn of the century. Before the RAD750 they used the RAD6000, a radiation hardened POWER1 chip. They also use the Mongoose rad hard MIPS chips in a number of orbiters.
  - cestith 4y ago
    I have a document on my bookshelf a few feet from here comparing the 386 to the 486 for space mission purposes. Its core conclusion was that the 486 on-die cache was not spaceworthy and that with it disabled integer math was not really faster than on the 386. The recommendation was to use the 386+387+plus an external cache, partly because compilers for the 486 all optimized for that internal cache and compiled code poorly with it disabled, even if adding external cache. Putting computers in space is not a simple thing, of course. Such documents as this point out some of the difficulties. "Analysis of the Intel 386 and i486 microprocessors for the Space Station Freedom Data Management System" Yuan-Kwai Liu NASA May, 1991 RTOP 488-51-01 ISBN 9781729173374 https://www.libreriauniversitaria.it/analysis-intel-386-and-i486/book/9781729173374 https://www.libreriauniversitaria.it/analysis-intel-386-and-...
    - giantrobot 4y ago
      That's interesting as the ISS (née Freedom) did in fact go with rad hard 386s for the MDMs (multiplexer-demultiplexer). These are the general purpose computers that connect dumb devices on the station like sensors or actuators to the station's main data bus. As for why Freedom/ISS went with 386s for the MDMs, I don't personally know. I'd guess that of the rad hard chips various defense companies shipped, a 386 was one of the more powerful. AFAIK the likes of the hardened RCA 1802 and some other 8-bit CPUs were pretty popular in the defense space. The RCA 1802 was used on a lot of the NASA's New Frontiers program probes. The MDM design on Freedom/ISS was meant to have a standardized component that was easily replaceable and use software to define the role of the device. An MDM plugged into a pump actuator today could have its EEPROM flashed and be plugged into a pressure sensor tomorrow. A useful feature in a system humans live in. That doesn't change the fact NASA's been RISC-y with their probes for the past three decades. The added power of the CPU (whatever the architecture) in today's probes means fewer specialized chips like were needed in older probes. That means more of the mass budget can go to science instruments and software can do the jobs that used to require dedicated chips. For anyone interested you can get the paper from NASA here[0]. It's pretty interesting. Thanks for pointing it out. [0] https://ntrs.nasa.gov/citations/19910016373 https://ntrs.nasa.gov/citations/19910016373
gumby 4y ago
There are already companies building hardware and software stacks so you can concentrate on the part you care about. I think this is great! Also excited to see RISC V gaining some acceptance in space.
SassyThrowaway 4y ago
> Especially if an open ISA means that our systems will be more portable and faster to develop. So I understand that RISC-V does not immediately impose licensing fees, but how does that translate into portability and speed of development? I'd think that tools and toolchains do not especially benefit from there not being licensing fees, and do benefit from somebody paying cool kernel/compiler hackers. Tools hardware designers use as well as the designs themselves will stay closed. What am I missing?

smoldesu 4y ago

It really seems like the perfect storm. Hopefully other folks like NASA will get comfortable jumping on the RISC train now that their only option isn't licensing from ARM.

giantrobot 4y ago
NASA's been on the RISC train for nearly 30 years. They've been using the RAD750 since the turn of the century. Before the RAD750 they used the RAD6000, a radiation hardened POWER1 chip. They also use the Mongoose rad hard MIPS chips in a number of orbiters.
- cestith 4y ago
  I have a document on my bookshelf a few feet from here comparing the 386 to the 486 for space mission purposes. Its core conclusion was that the 486 on-die cache was not spaceworthy and that with it disabled integer math was not really faster than on the 386. The recommendation was to use the 386+387+plus an external cache, partly because compilers for the 486 all optimized for that internal cache and compiled code poorly with it disabled, even if adding external cache. Putting computers in space is not a simple thing, of course. Such documents as this point out some of the difficulties. "Analysis of the Intel 386 and i486 microprocessors for the Space Station Freedom Data Management System" Yuan-Kwai Liu NASA May, 1991 RTOP 488-51-01 ISBN 9781729173374 https://www.libreriauniversitaria.it/analysis-intel-386-and-i486/book/9781729173374 https://www.libreriauniversitaria.it/analysis-intel-386-and-...
  - giantrobot 4y ago
    That's interesting as the ISS (née Freedom) did in fact go with rad hard 386s for the MDMs (multiplexer-demultiplexer). These are the general purpose computers that connect dumb devices on the station like sensors or actuators to the station's main data bus. As for why Freedom/ISS went with 386s for the MDMs, I don't personally know. I'd guess that of the rad hard chips various defense companies shipped, a 386 was one of the more powerful. AFAIK the likes of the hardened RCA 1802 and some other 8-bit CPUs were pretty popular in the defense space. The RCA 1802 was used on a lot of the NASA's New Frontiers program probes. The MDM design on Freedom/ISS was meant to have a standardized component that was easily replaceable and use software to define the role of the device. An MDM plugged into a pump actuator today could have its EEPROM flashed and be plugged into a pressure sensor tomorrow. A useful feature in a system humans live in. That doesn't change the fact NASA's been RISC-y with their probes for the past three decades. The added power of the CPU (whatever the architecture) in today's probes means fewer specialized chips like were needed in older probes. That means more of the mass budget can go to science instruments and software can do the jobs that used to require dedicated chips. For anyone interested you can get the paper from NASA here[0]. It's pretty interesting. Thanks for pointing it out. [0] https://ntrs.nasa.gov/citations/19910016373 https://ntrs.nasa.gov/citations/19910016373

gumby 4y ago

There are already companies building hardware and software stacks so you can concentrate on the part you care about. I think this is great! Also excited to see RISC V gaining some acceptance in space.

SassyThrowaway 4y ago

> Especially if an open ISA means that our systems will be more portable and faster to develop. So I understand that RISC-V does not immediately impose licensing fees, but how does that translate into portability and speed of development? I'd think that tools and toolchains do not especially benefit from there not being licensing fees, and do benefit from somebody paying cool kernel/compiler hackers. Tools hardware designers use as well as the designs themselves will stay closed. What am I missing?