tumbling in space

I came across this paragraph from wikip's Gemini_8 article:
"Emergency
There was some suspicion on the ground that the Agena's attitude control system was acting up and might not have the correct program stored in it. This suspicion was found to be incorrect. Shortly before radio blackout, Mission Control cautioned the astronauts to immediately abort the docking if any abnormalities occurred with the Agena.
After the Agena began execution of its stored command program, which instructed the Agena to turn the combined spacecraft 90° to the right, Scott noticed that they were yawing. Armstrong used the Gemini's OAMS thrusters to stop the yaw, but after it stopped, it immediately started again. Gemini 8 was out of range of ground communications at this time.
Armstrong reported that the OAMS fuel had dropped to 30%, indicating that the problem could be on their own spacecraft. With concern that the high yaw rate might damage one or both spacecraft or even cause the propellant-heavy Agena to rupture or explode, the crew decided to undock from the Agena so they could analyze the situation. Scott switched the Agena control back to ground command, while Armstrong struggled to stabilize the combined vehicle enough to permit undocking. Scott then hit the undock button, and Armstrong fired a long burst of translation thrusters to back away from the Agena. Without the added mass of the Agena, Gemini starting tumbling end-over-end more rapidly.
The astronauts realized that the problem was on the Gemini. NASA turned off the squawk box at Armstrong's home, alarming his wife[citation needed]. By now the tumble rate had reached one revolution per second, blurring the astronauts' vision and threatening loss of consciousness or vertigo. Armstrong decided to shut down the OAMS and use the Re-entry Control System (RCS) thrusters to stop the tumble. Scott later praised Armstrong's actions as their spacecraft spun: "The guy was brilliant. He knew the system so well. He found the solution, he activated the solution, under extreme circumstances ... it was my lucky day to be flying with him."[9] The spacecraft came in range of the ground communications ship Coastal Sentry Quebec. After steadying the spacecraft, the crew tested each OAMS thruster in turn and found that Number 8 had stuck on. Almost 75% of the reentry maneuvering fuel had been used to stop the tumble,[10] and mission rules dictated that the flight be aborted once the Re-entry Control System was fired for any reason. Gemini 8 immediately prepared for an emergency landing....
Cause and outcome No conclusive reason for the thruster malfunction was found. The most probable cause was determined to be an electrical short, most likely due to a static electricity discharge. Power still flowed to the thruster, even when it was switched off. To prevent recurrence of this problem, spacecraft designs were changed so each thruster would have an isolated circuit. ....
Spacecraft location The spacecraft is on display at the Neil Armstrong Air and Space Museum, Wapakoneta, Ohio."
Did the best computers use vacuum tubes in those days.
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On Thursday, October 11, 2018 at 1:26:07 AM UTC-4, micky wrote:

t,

No, they were semiconductor based. A computer with vacuum tube computers would never get off the ground.
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On 10/11/2018 12:26 AM, micky wrote:

...

I presume you don't really mean "best" here but are talking about onboard. See <https://www.ibiblio.org/apollo/Gemini.html for compendium of info that is available; it was custom designed/built by Federal Systems of IBM and is nothing like what we envision now as far as there being just a CPU on a board and some i/o...
--



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I think they were using the UC.5 processor that later became the support processor on larger systems along with being the main processor in smaller I/O
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That is not the one I was thinking of. That looks more like what we called the "Gusher" because of the relatively fast clock rate for those days.
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On Thursday, October 11, 2018 at 7:18:58 PM UTC-4, snipped-for-privacy@aol.com wrote:

According to the link, that Apollo guidance computer was built from 5600 nor gates and had a 1 mhz clock. A nor gate takes 4 or 5 transistors, so that would be about 25K transistors. Today's PC CPUs are in the tens of billions of transistors, 5 Ghz clock. That's some progress.
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On 10/11/2018 9:46 AM, dpb wrote:

great link,
7090 computer, 2000' long punched tape, custom assmbly code switch from FORTRAN II to FORTRAN IV occurred, but it could have been as early as 1963-64, in time for Gemini 7/6.
those were the days, not!
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wrote:

No
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Except for Sergio, all the replies were about my qustion about computers.
That was just an afterthought.
Mostly I hoped people would enjoy the story.
The Toronto group was using slide rules for some reason. Maybe they didn't even have vacuum tube computers yet. (Again, just an afterthought.)
In alt.home.repair, on Thu, 11 Oct 2018 01:26:01 -0400, micky

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