Nate Cull (.social)natecull@mastodon.social
May 28, 2018, 11:26 PMah, actually they did have 4096... 36-bit words of writeable core RAM. Weird. Was the Gemini computer *bigger* than the Apollo one ????
Replies
- Nate Cull (.social)natecull@mastodon.socialMay 28, 2018, 11:29 PM
The Apollo LVDC is the third computer on the ship that never gets any love cos it just ran the engines and wasn't sexy
- Nate Cull (.social)natecull@mastodon.socialMay 28, 2018, 11:30 PM
<< and the MIT Instrumentation Labs' antibodies flooded in to destroy the invader with critiques and reports negative of the IBM report. >>
lol programmers then just like today
- Nate Cull (.social)natecull@mastodon.socialMay 28, 2018, 11:34 PM
Ah! The LVDC had no ROM at all! Good lord. The entire program sat in RAM. Aaaaaaaaaaaa
- Nate Cull (.social)natecull@mastodon.socialMay 28, 2018, 11:42 PM
<< A so-called "bugger word" has been stuck at the end of each bank—no comments on this terminology, please, since I didn't invent it; when I asked Don Eyles some question that involved them, he somewhat-laconically stated "we called them check sums">>
- Nate Cull (.social)natecull@mastodon.socialMay 29, 2018, 12:00 AM
Huh, and if you have ROM and RAM I guess it literally is a Harvard Architecture
http://www.ibiblio.org/apollo/BlockIII.html
I never thought of that before!
May 28, 2018, 11:36 PM@natecull please tell me they at least had a bunch of toggle switches somewhere in case it got wiped so houston could read it back to them and they could program it back in
- May 28, 2018, 11:37 PM
@natecull innovative Over-The-Air Update feature
Jan 4, 2023, 6:21 PM@jk @natecull it was CORE ram, which is nonvolatile. You can still recover the databits in the old core planes you find on ebay, but you have ONE (1) chance to get them right. If your sense amps dont work and cant read them, it's done. The cores can only be read destructively and need immediate reprogramming to retain the value.
If you already know this please forgive me, I just think it's cool info that will be interesting for someone else.
Jul 9, 2023, 12:08 AM@natecull Magnetic cores are non-volatile. So no ROM needed. Von Neumann all the way.
nilrognilrog@mastodon.nuJan 5, 2023, 8:25 AM@natecull I’m going to use “bugger word” instead of checksum from now on 😁
Mechele Gmechele@infosec.exchangeJan 4, 2023, 8:50 PM@natecull I have fond memories of a system that I created a boot disk for which rewrote the operating system to all things to do with bunnies. To RUN something you had to HOP it, etc. I would boot the computer with my disk and then watch my friend try to figure out what I’d done. We had many laughs at that.
- Jul 9, 2023, 12:02 AM
@natecull I was a coop in Astrionics lab. The LVDC guys were down the hall. LVDC did more guidance and nav then engine control.
Those guys bragged that they hit their orbits within 50 feet on every Apollo flight. 
Íñigo Huguetihuguet@mastodon.socialJan 6, 2023, 8:46 AM@natecull and what about the speed? Clock frequency of SEVEN HERTZ!!!
Clifton RoystonCliftonR@wandering.shopOct 28, 2024, 10:35 AMFrom my reading, 18-bit and 36-bit architectures were popular through the '60s and early '70s. Computer designs didn't really settle down to power-of-2 word sizes until the mid-70s.
There were weirder sets of numbers in use too - 24-bit, 30-bit, 48-bit, 60-bit, etc.
Stumpy The MuttStumpyTheMutt@social.linux.pizzaOct 28, 2024, 1:02 PM
Oct 28, 2024, 9:59 PM- Clifton RoystonCliftonR@wandering.shopOct 28, 2024, 10:08 PM
Yep, I just summarized by giving some of the more popular ones.
Wikipedia lists some really oddball ones - 25 bit, 26 bit (from IBM!), and even 31 bit!
That last was a crippled 32-bit computer made for selling into the Soviet bloc when selling them 32-bit CPUs was prohibited due to military applications.
Yes, I fell down a Wiki rabbit hole double-checking my facts before replying.
Timjantimjan@social.linux.pizzaOct 29, 2024, 6:54 AM
Oct 12, 2026, 8:05 PMIIRC my work on raw GPS data down links, decades ago (for some French official agencies), GPS words were 5 x 6 bits "sextets" instead of octets (30 bits words)
The sextets bit ordering was in the opposite direction of the endianness of the 30 bits word.
Required some translation routines to-from 64 bits sytems (Linux).
Was a 24/365 monitoring system providing data for geodesy post processing (RINEX) and to some Aviation Security agencies (eventual proof of GPS spoofing)
