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Apollo On Board Computer Emulator
frankk74 writes "For those of you interested in Historical Computing and the Apollo manned spaceflights Ron Burkey has created a open source emulation of the Apollo Guidance Computer called vAGC. I use it as my desktop clock of choice. Note it only keeps mission time so after 24 hours you have reset the time :-). P.S. Another cool Apollo toy free and payware can be found here."
In three two one... Huston, we have a problem.
"It is a miracle that curiosity survives formal education." - Albert Einstein
Took a quick scan at the architecture of the machine, and I'm suprised that it's so simple.
People say over and over again that simple handheld calculators are more powerful than that thing, and it seems that the oft-parroted line is more accurate than they realize.
Add to that: RTL (before TTL) and magnetic core memory bring up the nostalgic value.
What I would like to see is a complete Apollo computing system simulator, consisting of the hardware simulator, where you could realistically simulate the effects of increased core voltage, heat, power surges, fluctuations, etc. coupled with the hardware emulator capable of running native Apollo code, just like vAGC.
Do they have this at NASA? For them it must be easier and more reliable to just use an identical environment for testing purposes, but some Apollo enthusiasts would enjoy tinkering with such a combined simulation-emulation environment (SEE).
A quick inspection of an Apollo capsule reveals why they didn't just use a PDP8.
Think of three fat guys trying to move one of those things in a Mini Cooper.
KFG
...without having a "Start" button? ;)
I tried to use this to run games. It didn't work at first, there just wasn't enough power. Then I used the gravitational pull of my neighbor's house as a slingshot and was running Doom 3 in no time.
And they made Buzz Aldrin sit in the back. No wonder he gets cranky if someone says that he didn't go to the Moon!
One line blog. I hear that they're called Twitters now.
Humorous snippet from the landing module code...
...
P63SPOT3 CA BIT6 # IS THE LR ANTENNA IN POSITION 1 YET
EXTEND
RAND CHAN33
EXTEND
BZF P63SPOT4 # BRANCH IF ANTENNA ALREADY IN POSITION 1
CAF CODE500 # ASTRONAUT: PLEASE CRANK THE
TC BANKCALL # SILLY THING AROUND
CADR GOPERF1
TCF GOTOP00H # TERMINATE
TCF P63SPOT3 # PROCEED SEE IF HE'S LYING
P63SPOT4 TC BANKCALL # ENTER INITIALIZE LANDING RADAR
CADR SETPOS1
TC POSTJUMP # OFF TO SEE THE WIZARD
CADR BURNBABY
They didn't use artificial gravity to seperate the LOX; quite the opposite.
In fact, in zero gravity LOX tends to divide up into regions of gas and liquid. If the gas happens to float past the sensor, then they get an incorrect reading of the density, and hence they don't know how much is in there. This was a big problem on previous flights. Stirring the tank mixes it all up and makes it the same density; allowing a reliable reading to be taken.
Yes and no. In zero g the bubbles and liquid have no reason to separate. In a gravity field the bubbles float just like the do in water - so you get a liquid without voids in it - which you can measure.
Aluminum, particularly bulk aluminum is *not* combustible in LOX. It's used on the Space Shuttle main tank fer heavens sake!
Aluminum will burn in air if there is enough energy to break through the surface layer of aluminum oxide which builds up on the surface. In fact aluminum is so reactive with oxygen that this layer forms instantly when the metal is exposed to oxygen. Anything which will burn in air will really burn in LOX.
Graphite can't really burn either; for it to burn it needs to reach ~3000K, and the LOX is pretty keen on it not reaching that temperature.
There was an experiment where a scientist used LOX and charcoal to see how fast it would burn - it esentially flashed in less than a second. DO NOT ATTEMPT THIS. IT IS RIDICULOUSLY DANGEROUS. Your statement is like saying Nitro Glycerin is safe to have in your house. NOTE FOR THE YOUNG AND INEXPERIENCED: DO NOT STORE NITRO GLYCERIN IN YOUR HOUSE. IT WILL BLOW UP AND KILL YOU!!!
Provided the brushes are carefully chosen, this need not be a problem.
This is exactly the sort of thinking which resulted in the original disaster. Brushes are mechanical devices - there is inductance in a motor - when the brush connection is broken the inductance of the motor will cause a spark. We have studied the ignition properties of such sparks in LOX in my group. There is a statistical probability of a given spark igniting the brush material.
That's not actually what caused the explosion anyway.
During testing a relay welded itself shut due to incorrect voltages. In flight, the wiring overheated- and the insulation burnt in the LOX. That caused the LOX tank to overpressure, and it blew away half the side of the vehicle
That is the official theory which was reached by people who knew nothing about the spark ignition problem. The voltage in the GFE power supply used in the test was not enough to weld contacts - the LOX would have cooled the wires so that they wouldn't have reached ignition temperature. The explosion didn't happen until the tank was stirred. The thinking behind reaching that official theory was "Well none of the other tanks blew up so the design was OK so it must have been someing which was done to that particular tank that caused the problem."
Thanks for demonstrating the "Whirr click, whirr click " mind set to everyone.