Tom Lyon ✅Jun 12, 2023
#MainframeMonday The IBM 9020 was a "clustered" system for FAA air traffic control consisting of multiple IBM 360s - for redundancy and parallelism. https://en.wikipedia.org/wiki/IBM_9020 #ComputerHistory
IBM 9020 - Wikipedia

Show threadJohnMasheyJun 12, 2023

@aka_pugs
~1980 FAA Was looking for replacements, and Bell Labs got asked (I think) to consider bidding on it. I got asked by my director to look at code ... which was IBM S/360 assembler, including some nonstandard instructions added to 360/50 microcode to make some computation go fast enough.

I didn't fly for a while...

Show threadcynicalsecurity Jun 12, 2023
@JohnMashey “go fast enough” is the kind of expression which I do not feel comfortable associating with air traffic control… having said this the Bell Labs document on the Sprint/Spartan ABM code mentions how shaving some ms from a calculation “might save Philadelphia”… @aka_pugs
Show threadJohnMasheyJun 12, 2023
@cynicalsecurity @aka_pugs
It’s been 40+ years … but I recall this code was part of real-time input processing, probably something to accelerate handling of some nonstandard data formats by microcode implementation.That kind of thing needs predictable timing that is “fast enough”😊
I worked with folks who’d been involved with Safeguard ABM. They all said:
1) met the specs!
2) and in a real attack, goodbye…
Show threadcynicalsecurity 

@JohnMashey thank you for the historical context - I'm too young and part of the "Nuclear War in Europe" PTSD generation so for me Safeguard remains mostly an incredibly sophisticated technology from the 1960s. It was also always rather clear to me that when the US OPLAN had assigned 69 warheads just to take out the ABM around Moscow the chances of us ever surviving nuclear war were (and are) pretty much zero all along…

I am quite interested in the µcode implementations you mention: would it be possible to elaborate or give me references to read up on it? I have dabbled with µcode (on Intel/AMD) and am interested in both malicious and useful modifications.

@aka_pugs

Jun 14, 2023 at 6:14amWeb
Show threadJohnMasheyJun 14, 2023
@cynicalsecurity @aka_pugs
Yes, Nuclear War would be a Bad Thing.
In early 1970s I wrote most of a fast S/370 assembler for students:
https://en.wikipedia.org/wiki/ASSIST_(computing)
so I knew S/370 opcodes rather well, why I got asked to look at the 9020 code.
I recognized nonstandard opcodes when I looked at code, but knew nothing of the underlying microcode extras, but there is a some discussion here:
https://en.wikipedia.org/wiki/IBM_System/360_Model_50
And IBM Sys Jm vil 6, no 2.
This has TOCs only, but a start.
https://ftp.math.utah.edu/pub/tex/bib/toc/ibmsysj.html
ASSIST (computing) - Wikipedia

Show threadcynicalsecurity Jun 14, 2023
@JohnMashey oh, thank you :)
@aka_pugs