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Author Topic: Virtual AGC P06 "Standby mode"  (Read 12810 times)
bluespace88
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« on: April 10, 2008, 04:19:18 AM »

Tried with both orbiter and yaAGC, but I can't seem to get the CMC to shutdown all the way.  I do get a standby light when I enter V37E06, and I get the flashing V50N25 and have R1 as 00062, but hitting or holding down PRO does not cause the computer to shutdown.  I know of at least one topic on here that seems to have it working, and I'm wondering how it is done, as I do notice that the actual manual and the doc provided in project apollo is different with respect to the shutdown procedure.
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Tschachim
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« Reply #1 on: April 10, 2008, 05:35:50 AM »

Yes, VAGC standby mode isn't working, sorry. We didn't figure out how it works yet, basically because a lot of the standby mode is handled outside the AGC as far as I know.

Cheers
Tschachim
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bluespace88
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« Reply #2 on: April 10, 2008, 09:27:08 AM »

ok, thanks for the answer.
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dseagrav
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« Reply #3 on: April 10, 2008, 01:02:06 PM »

As I understand it, P06 somehow causes a relay outside of the computer to open a switch that partially shuts down the power supply. I never found the means by which the relay was triggered. If someone can figure out which bit where, we can try to handle it.

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movieman
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« Reply #4 on: April 10, 2008, 01:31:50 PM »

There is some kind of standy input or output bit on the AGC, isn't there? Maybe we could figure things out from the source code for the P06 function.
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irnenginer
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« Reply #5 on: April 10, 2008, 02:35:12 PM »

Looks to be Bit 11 of CHAN13 (standby enable) goes 1 during standby.
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Tschachim
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« Reply #6 on: April 10, 2008, 02:46:12 PM »

As far as I remember this channel bit controls the STBY light on the DSKY and comes up before you actually press PRO, but perhaps if both this bit and the PRO key are present the AGC goes to standby? There are some details in one of the systems handbooks, I'll try to investigate...

Cheers
Tschachim
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bluespace88
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« Reply #7 on: April 10, 2008, 03:28:19 PM »

the light should come on after pressing pro and not before.

As far as I know, Channel 13 controls test alarms and lights and the standby light, but thats just for vAGC.  Not sure how the real AGC handles it, but I can take a look as well, as right now I don't know where it is headed to on the schematic.
« Last Edit: April 10, 2008, 03:33:08 PM by BlueDragon8144 » Logged
Tschachim
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« Reply #8 on: April 10, 2008, 05:15:21 PM »

Yes, you're correct. Meanwhile I found what I was looking for, unfortunately it doesn't help much. Anyway, the diagram I mean is in this fragment of the LM systems handbook, I attached the relevant section below: http://www.ibiblio.org/apollo/Documents/LM_Systems_Handbook_060269.pdf

P06 sets the standby bit and if the PRO key is pressed, too, the standby light of the DSKY is turned on and the signal is routed to something on drawing 10.7, which seems to be not available.  Confused

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Tschachim


* agcstby.jpg (225.02 KB, 1617x922 - viewed 365 times.)
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dseagrav
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« Reply #9 on: April 10, 2008, 06:03:08 PM »

It can't be just the lamp bit, otherwise the AGC would standby when you did a lamp test.
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bluespace88
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« Reply #10 on: April 10, 2008, 06:07:57 PM »

which is that other signal that is sent off to somewhere where we don't have the schematics for. 
There's still the Apollo 9 Systems Handbook to look through.

More info on the channel 13 bit for the light: The word number is 92A
« Last Edit: April 11, 2008, 03:20:46 AM by BlueDragon8144 » Logged
kneecaps
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« Reply #11 on: May 04, 2008, 12:23:23 PM »

I'll look at this mechanism when I'm done with the FDAI error needles.
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
kneecaps
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« Reply #12 on: May 09, 2008, 07:12:30 PM »

Okay..things don't look good on a proper P06 standby. I currently feel a yaAGC changes/work/new code is required.

This is how it apparently functioned with the real hardware/software

1) Enter P06 (after killing the DAP of course!)
2) Hold PRO for upto 5 seconds (until STBY illuminates).

How this put the AGC into standby:

1) P06 does various cleanup stuff which our vAGC does.
2) P06 Sets the output chan 13 bit 11 to 1.
The output feeds into an AND gate that's wired to the pro key according to the drawing.

However what happens next is the key. P06 setting the ENABLE STANDBY bit and the PRO key being held causes an input contact on the AGC known as 'STANDBY ALLOWED' to close. When 'STANDBY ALLOWED' is closed the AGC begins to output a modified switching signal to it's power supply. This switching signal causes the AGC power supply to cease generation of one of three of its power outputs (3vdc B supply).

As long as the 3vdc B signal from the powersupply is inhibited then various counters etc etc will not advance and the machine is in standby.

So in short, I don't believe the AGC emulator models any of the hardware type functions beyond whats needed to run the code and produce 'computer' IO.

That's not to say some code couldn't be added to inhibit the emulator by copying the end result of killing the power (which is stopping the
various counters).

Pete
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
kneecaps
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36711000 kneecaps@shockpulse.co.uk
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« Reply #13 on: May 10, 2008, 06:13:55 AM »

Since this is a 'physical' hardware part of the AGC, it is going to need to be added in some way to the AGC engine. If there is real interest in having this function (did they EVEN actually put the CMC into STBY in the real flights) work I can continue to research, come up with a spec and prehaps attempt to produce a patch or make a suggestion to Ron on how to implement it?

I don't believe it's much work for somebody familiar with yaAGC code, but 80% of my time to implement would be swallowed up by learning the code.

Pete 
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"Okay. As soon as we find the Earth, we will do it."
- Frank Borman, Apollo 8

Current Work: ?? What next??

Future Work:
I know the AGC pretty well so anything need doing there?

On Hold/Completed:
SPS TVC in P40 issues.
P11 FDAI Error Needles (98%) complete. Comitted. Working A7 scenario.
P06 AGC Standby. Concluded. It's done by the AGC PSU.
Got us a complete AOH Volume II
movieman
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« Reply #14 on: May 10, 2008, 12:16:30 PM »

I presume Apollo 13 used standby.

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