6 ms·

I started my career working for British Aerospace in 1989. We used VAX/VMS as our development platform (Code was CORAL 66 and then ADA). I spent some time suppo

I started my career working for British Aerospace in 1989. We used VAX/VMS as our development platform (Code was CORAL 66 and then ADA). I spent some time supporting the Sea Harrier flight test operations - so I would have fitted this job perfectly about 28 years ago!). I'd like to say that I'm astonished that modern aircraft still use the 1553 bus, but nothing surprises me when it comes to the use of stone-age tech in military hardware. For example, the other Harrier I worked on in the early 90s (GR-7 - same as US AV8B) still used core memory.

Phlarp 7y ago
That's insane. A 3d matrix of ferrite rings suspended by wire would seem (to me) somewhat sensitive to vibrations or gforces. Military gonna military I guess.
- anyfoo 7y ago
  The same technology was very successfully used to fly to the moon. Cores aren’t so much suspended when they are wholly embedded in epoxy.
  - jackfraser 7y ago
    Stupid question, but the cores don't physically flip, do they? It's a purely electrical thing?
    - muzika 7y ago
      Yes
    - gattilorenz 7y ago
      It's the magnetic field that flips, the ferrite cores remain in place
    - m463 7y ago
      I think it's just clockwise vs counterclockwise.
- dvdkhlng 7y ago
  But on the other hand core memory is very resilient against EMP and hard radiation :)
- alex_hitchins 7y ago
  I seem to recall something along the lines of large bombers running valves as they were less prone to effects of EMP around nuclear blasts. Not sure if this perhaps something similar?
  - jabl 7y ago
    In one of the documentaries about the Vulcan raid on the Falklands (1982), one of the pilots interviewed remarked that somebody flying Avro Lancasters in WWII would have felt right at home in the cockpit of the Avro Vulcan. E.g. the navigator used mechanical clocks to keep track of when to turn, and so on. Not sure if this was a conscious decision wrt EMP, or was it just that they were in a hurry to develop a jet bomber for delivering nukes and they reused existing stuff as much as possible.
    - NeedMoreTea 7y ago
      Not in the least surprising. The Vulcan prototype, the 707, first flew in 1949. They even had a mount for the old Lancaster bomb sight - though that was mostly used for a camera. Flight engineer and radar operator in the seats behind would have got the fancy new (for the early 50s) electronic things.
      - mhh__ 7y ago
        The Lancaster was loaded with the technology of the time by the end up the war e.g. they had radar navigation, radio navigation, (when it worked) a 'lock' detector for German night fighter radar
    - johncalvinyoung 7y ago
      Which documentary was this? I read Vulcan 607 about ten years ago and loved it.
      - jabl 7y ago
        I'm quite sure it's this one: https://www.youtube.com/watch?v=PBJ99bIhAVk https://www.youtube.com/watch?v=PBJ99bIhAVk
- tirpen 7y ago
  For airplanes flying at high altitudes with modern computers, random bit flips from comsmic radiation is actually a very real threat that has to be considered. IIRC there's about a factor of about 300x more radiation at 30000 ft and 900x at 60000 ft. Core memory is a lot less sensitive to this than most memory types, so it makes some sense to store the most flight critical data in such a memory.
  - adrianN 7y ago
    The sensible way to deal with bit flips is a gratuitous amount of ECC.
    - akiselev 7y ago
      ECC doesn't help when you have an EMP caused by an atmospheric nuclear detonation. Those are the kinds of things the design has to consider.
      - devonkim 7y ago
        Makes me why we don’t count NASA under DoD similar to DARPA to help with their funding.
        mikeash 7y ago
        NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force.
        wolfgke 7y ago
        > NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force. Not the Space Force? > https://www.buzzfeednews.com/article/briannasacks/trump-space-force https://www.buzzfeednews.com/article/briannasacks/trump-spac... ;-)
        Kadin 7y ago
metaphor 7y ago
> I'd like to say that I'm astonished that modern aircraft still use the 1553 bus... What's wrong with 1553? It's reliable, battle-tested, and the latest revision C was published 28-Feb-2018. In contrast, the RS-232 PHY dates back to 1960, yet it's quite alive and well in modern commercial devices. As a consolation, be glad you've never had to deal with the monster that is STANAG 5516/MIL-STD-6016...if there was such a thing as a "modern" interface standard whose sheer page count (11,410 pages!) would make any sensible engineer reconsider future career prospects.
- euler_angles 7y ago
  As someone who has read all of 6016, doing so cost me a good chunk of my sanity. Never mind the fact that many areas of the standard don't matter because the manufacturers of equipment that use those areas made up their own way of doing things that isn't 6016 compliant. So you can comply to the standard, or you can actually work with platforms in the real world, but you can't do both.
  - bencollier49 7y ago
    Ah, that's like RFC 4210 for PKI!
  - atribecalledqst 7y ago
    I've read and nearly memorized large portions of 6016 as well and I can commiserate with you. I feel a bit of pride mixed with shame at the fact that I know how to quickly jump around in the document and follow all the threads of logic. On the whole I think it's an interesting read, though. And I'm sure knowing it so well doesn't hurt my employability in the industry. Technically I think platforms are supposed to document the areas where they're noncompliant with 6016 and submit it for approval. The name of the process escapes me at the moment. Not sure if anybody ever does it, though.
    - euler_angles 7y ago
      The biggest noncompliant areas I know of are...difficult to even talk about.
euler_angles 7y ago
The 1553 bus is ancient, but it's electrically and logically simple. The concepts necessary to use and incorporate 1553 into designs is easily acquired by a fresh engineer (I should know, I first used 1553 in a design as a 24 year old straight out of grad school) and it's already incorporated into all kinds of avionics and weapons. Why not use it?
wrp 7y ago
What was your experience switching from Coral 66 to Ada? An equivalent language in the USA at the time was JOVIAL. I heard from some old JOVIAL programmers that they thought Ada was an inferior tool for the job. When I looked at Coral 66, it seemed to be rather less polished than JOVIAL, so I have wondered whether British programmers might have welcomed the switch to Ada.

Phlarp 7y ago

That's insane. A 3d matrix of ferrite rings suspended by wire would seem (to me) somewhat sensitive to vibrations or gforces. Military gonna military I guess.

anyfoo 7y ago
The same technology was very successfully used to fly to the moon. Cores aren’t so much suspended when they are wholly embedded in epoxy.
- jackfraser 7y ago
  Stupid question, but the cores don't physically flip, do they? It's a purely electrical thing?
  - muzika 7y ago
    Yes
  - gattilorenz 7y ago
    It's the magnetic field that flips, the ferrite cores remain in place
  - m463 7y ago
    I think it's just clockwise vs counterclockwise.
dvdkhlng 7y ago
But on the other hand core memory is very resilient against EMP and hard radiation :)
alex_hitchins 7y ago
I seem to recall something along the lines of large bombers running valves as they were less prone to effects of EMP around nuclear blasts. Not sure if this perhaps something similar?
- jabl 7y ago
  In one of the documentaries about the Vulcan raid on the Falklands (1982), one of the pilots interviewed remarked that somebody flying Avro Lancasters in WWII would have felt right at home in the cockpit of the Avro Vulcan. E.g. the navigator used mechanical clocks to keep track of when to turn, and so on. Not sure if this was a conscious decision wrt EMP, or was it just that they were in a hurry to develop a jet bomber for delivering nukes and they reused existing stuff as much as possible.
  - NeedMoreTea 7y ago
    Not in the least surprising. The Vulcan prototype, the 707, first flew in 1949. They even had a mount for the old Lancaster bomb sight - though that was mostly used for a camera. Flight engineer and radar operator in the seats behind would have got the fancy new (for the early 50s) electronic things.
    - mhh__ 7y ago
      The Lancaster was loaded with the technology of the time by the end up the war e.g. they had radar navigation, radio navigation, (when it worked) a 'lock' detector for German night fighter radar
  - johncalvinyoung 7y ago
    Which documentary was this? I read Vulcan 607 about ten years ago and loved it.
    - jabl 7y ago
      I'm quite sure it's this one: https://www.youtube.com/watch?v=PBJ99bIhAVk https://www.youtube.com/watch?v=PBJ99bIhAVk
tirpen 7y ago
For airplanes flying at high altitudes with modern computers, random bit flips from comsmic radiation is actually a very real threat that has to be considered. IIRC there's about a factor of about 300x more radiation at 30000 ft and 900x at 60000 ft. Core memory is a lot less sensitive to this than most memory types, so it makes some sense to store the most flight critical data in such a memory.
- adrianN 7y ago
  The sensible way to deal with bit flips is a gratuitous amount of ECC.
  - akiselev 7y ago
    ECC doesn't help when you have an EMP caused by an atmospheric nuclear detonation. Those are the kinds of things the design has to consider.
    - devonkim 7y ago
      Makes me why we don’t count NASA under DoD similar to DARPA to help with their funding.
      - mikeash 7y ago
        NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force.
        wolfgke 7y ago
        > NASA exists to be the civilian side of the US’s aerospace ventures. The military side is the Air Force. Not the Space Force? > https://www.buzzfeednews.com/article/briannasacks/trump-space-force https://www.buzzfeednews.com/article/briannasacks/trump-spac... ;-)
      - Kadin 7y ago

metaphor 7y ago

> I'd like to say that I'm astonished that modern aircraft still use the 1553 bus... What's wrong with 1553? It's reliable, battle-tested, and the latest revision C was published 28-Feb-2018. In contrast, the RS-232 PHY dates back to 1960, yet it's quite alive and well in modern commercial devices. As a consolation, be glad you've never had to deal with the monster that is STANAG 5516/MIL-STD-6016...if there was such a thing as a "modern" interface standard whose sheer page count (11,410 pages!) would make any sensible engineer reconsider future career prospects.

euler_angles 7y ago
As someone who has read all of 6016, doing so cost me a good chunk of my sanity. Never mind the fact that many areas of the standard don't matter because the manufacturers of equipment that use those areas made up their own way of doing things that isn't 6016 compliant. So you can comply to the standard, or you can actually work with platforms in the real world, but you can't do both.
- bencollier49 7y ago
  Ah, that's like RFC 4210 for PKI!
- atribecalledqst 7y ago
  I've read and nearly memorized large portions of 6016 as well and I can commiserate with you. I feel a bit of pride mixed with shame at the fact that I know how to quickly jump around in the document and follow all the threads of logic. On the whole I think it's an interesting read, though. And I'm sure knowing it so well doesn't hurt my employability in the industry. Technically I think platforms are supposed to document the areas where they're noncompliant with 6016 and submit it for approval. The name of the process escapes me at the moment. Not sure if anybody ever does it, though.
  - euler_angles 7y ago
    The biggest noncompliant areas I know of are...difficult to even talk about.

euler_angles 7y ago

The 1553 bus is ancient, but it's electrically and logically simple. The concepts necessary to use and incorporate 1553 into designs is easily acquired by a fresh engineer (I should know, I first used 1553 in a design as a 24 year old straight out of grad school) and it's already incorporated into all kinds of avionics and weapons. Why not use it?

wrp 7y ago

What was your experience switching from Coral 66 to Ada? An equivalent language in the USA at the time was JOVIAL. I heard from some old JOVIAL programmers that they thought Ada was an inferior tool for the job. When I looked at Coral 66, it seemed to be rather less polished than JOVIAL, so I have wondered whether British programmers might have welcomed the switch to Ada.