Minuteman D-17b: The Desktop Computer Was Born in an ICBM

At 26:14 I should have said 'dodecagon' not 'dodecahedron'. My script even said the correct term, I just read it wrong! Thanks @__a_4444 I recommend Usagi Electric's video on the Bendix G15 drum memory for anyone wanting to know more about exactly how the magnetic disc storage worked. The drum memory he describes is almost identical, just in a different form factor. He is able to communicate it far better than me and answers questions a few viewers here have asked in the comments. 1:01:19 should be the Gemini computer, I have absolutely no idea why I said ‘Mercury’ (which didnt have a computer). Thanks @AMcAFaves https://www.youtube.com/watch?v=ijRV_7sr4_k

So technically the missile knew where it was because it knew where it was, and by subtracting where it was from where it ought to have been it can derive a difference, or delta velocity…

"Your first desktop will blow you away". (I'll show myself out).

"Jesus, your computer is slow. What are your specs?" "One 800 kilotonne thermonuclear warhead." "What?"

apparently, IBM was the abbreviation for intercontinental ballistic missile, its all coming together

Real talk, "can it doom," is actually one of the best definitions of a computer I've ever heard. It's simultaneously very easy to understand and very accurate

21:28 The reason why thrust termination ports work is due to the St. Roberts Burn Rate Law. It states that the regression rate, or how fast the propellant is burning back, is equal to a constant a times chamber pressure raised to the constant n power: rb = a*Pc^n. The a and n coefficients are based on the propellant mixture and are determined through strand burner analysis. When the thrust termination ports open, the chamber pressure drops rapidly, and thus the regression rate goes down. This is known as 'quenching'. The ports are angled forwards because the regression rate will not reach zero immediately, and will instead taper off as gas exits both the nozzle and the open ports. The angle of these ports results in zero net thrust. Some ICBMs actually angle the ports further forwards and use them to 'back off' the spent stage from the warheads and guidance bus. If you'd like to learn more there are a few good NASA papers online on solid motor quenching.

So they gave a serial number to every resistor in a computer and tracked it all using paper. A logistical nightmare is an understatement.

Maybe Alexander only the ok, but man, that film was great

Spinny magnetic things were apparently a pretty established memory technology back then. A fella on Usagi Electric youtube channel is restoring a 1956 vacuum tube computer that uses a large magnetic drum at its core. The drum that came in his machine was shot but he managed to find another one in better condition in a museum machine and swap it.

A CNC controlled by a Minuteman guidance computer is the most awesome thing I've heard in a while! Amazing video as always

Back in the mid 70s we had one of the University donation units in our EE department. One of the advanced students built a seven segment numitron display (incandescent filaments) and switch setup that could be used to enter short programs. The S/N on each component was no joke. For their time the components were top notch. Our unit consisted of the processor half of the round split apart and mounted on a rack. I was very impressed by the reverse voltage protection. There was a huge stud mounted rectifier across the power input ready to short out the supply if it was connected up backwards. Sadly no exciting projects were ever built around it.

Beryllium is exceptionally stiff. It is terrible to work with, the dust in particular though. Great video, thank very much for the time these take.

JWST primary mirrors are made from beryllium with a thin gold coating. Very minimal expansion coefficient , so the mirror alignment won't need massive corrections

Early computers like this are fascinating, stuff like the core rope used in the AGC, really amazing tech.

27:00 - Huh! The pcb’s make me think of isolinear chips on Star Trek TNG. Very cool that this was possible back then!

I commanded a Missile Combat Crew in the early 80s. My system was Minuteman III. One morning when I was sitting in the Squadron waiting to go on alert, I happened to stumble upon an old Dash 1 Tech Order for the original Minuteman I system and started to read. I was shocked to learn that the first Launch Control system had no computer at all. The entire thing was based on mechanical relays. The Enable commands were simply electrical continuity circuits. Interrupt the circuit and the sortie enabled. If power at the capsule dropped, all the sorties in the flight would enable. Daily SCN tests dropped connected sorties into Standby mode so the crew could verify communication. The whole design was surreal to me given all the nuclear surety that was deliberately built into the software that I used. I couldn't conceive of that kind of system without a computer. But I guess it makes sense given the level of technology in the early 60s. The computer in my capsule was a Rolm 1666B, especially built for the mission. Not much by today's standard but it did the job.

Soviet R7 used measurement and correction ground stations. But the first generation of R7 was more of a technology demonstrator or stop-gap solution than weapon system Later rockets used vacuum tube computers on board, with miniaturized vacuum tubes which had a size like a small part of the pencil and a lifetime from several minutes to several hours.

The Hard Drive architecture isn't as confusing if you think about it as a solid state version of delay line memory.

I love this series on early computing history! The intersection with the more advanced weapons of war is fascinating (although very much expected); I may abhor war but its still a very interesting topic (probably because of them having to solve novel, and difficult problems), which further complements my interest in learning about early computers and the like. I appreciate you way of relaying information in videos quite a bit too!