Talk:Launch Vehicle Digital Computer

Has anyone ever thought to ask if the software could be read from the units on display? 128.194.22.23 18:01, 19 February 2007 (UTC)

I know someone has tried to get hold of the software without any luck so far. I don't know whether they've tried to get access to the displayed Saturn IUs, or whether reading the core memories would even be feasible without specialised hardware. Mark Grant 00:32, 20 February 2007 (UTC)

"with a 2.048 MHz clock cycle, add operations taking 82 microseconds" So "add operations" took 168 clock cycles? Is the LVDC is a kind of serial computer? --68.0.124.33 (talk) 06:09, 4 March 2008 (UTC)

I believe so, yes: the documentation says "the Add/Subtract circuit serially adds or subtracts the contents of the accumulator, the contents of the addressed memory location and any carry that develops from the previous bit summation." Would be worth adding some more info about how the internals worked but it's not particularly clear :). Mark Grant (talk) 02:04, 4 June 2009 (UTC)

I have some LVDC Core Memory Blocks and Page Card Assemblies within my private collection that are photo documented with a description of the LVDC on my personal website. The direct URL is http://www.spaceaholic.com/lunar_module_saturn_v.htm . Please feel free to reference the material on my site if you think it will enhance this article on the LVDC. Spaceaholic (talk) 21:45, 16 October 2008 (UTC)

NASA links dead in 2013

Existing links to NASA reports are dead, and I wasn't able to find them on the NTRS. From http://www.sti.nasa.gov/find-sti/ [30 Nov 2013]: "On March 20, 2013, the NASA Administrator directed that the NASA Technical Reports Server (NTRS) be taken off-line while the Agency conducted a review of whether there is a risk of export-controlled documents being made available on the NTRS website.". For more info regading where this comes from go to [[1]]. Not sure why they bothered since the military of just about every capable nation on earth likely scraped the entire NTRS years ago. Here's one interesting report I was able to track down: Saturn V Apollo Launch Operations Plan [[2]] 203.129.23.146 (talk) 23:14, 29 November 2013 (UTC)

Dates

Some key dates would be welcomed.

Work on computer started around 1963 [3], or even 1962 [4]. --89.25.210.104 (talk) 20:57, 5 April 2018 (UTC)

Originally known as the Saturn Triple Modular Redundancy computer (TMR) [5] - Rod57 (talk) 14:43, 1 November 2018 (UTC)

Questions - could cover

• was the LVDC hardware and s/w architecture based on any earlier computer ? (maybe Gemini Guidance Computer, also by IBM)
• did it have RAM and ROM ? (just r/w core memory ?)
• how were programs prepared ? (punch cards?)
• how was software loaded into the LVDC ?
• how were control signals output ? - Rod57 (talk) 15:07, 1 November 2018 (UTC)

[6] says it had 18 'discrete' outputs and 25 pulsed outputs (& telemetry downlink)

Saturn Launch Vehicles TR X-881 describes the process input-output instruction on pages 20-79 to 20-84. - Rod57 (talk) 12:01, 2 November 2018 (UTC)

[7] p25 says there were ultrasonic glass delay lines for serial arithmetic and storage of the instruction counter. - Rod57 (talk) 17:32, 1 November 2018 (UTC)

• was the circuitry implemented in the 12 layer? boards (MIBs with up to 35 ULDs) or in the back plane they were plugged into ?
• was the voting logic (between the 7 modules in each redundant channel) implemented on the MIBs, (dedicated or mixed with the logic ?) - Rod57 (talk) 12:48, 2 November 2018 (UTC)

Was the LVDA "Enclosure B" ?

[8] p15 says Enclosure A: Timing, Control and Arithmetic, Memory. Enclosure B: power, Interrupt Logic, Input-Output Digital and Analog Circuits. - Rod57 (talk) 15:24, 1 November 2018 (UTC)

This article should describe LVDA too, as it is specific to LVDC - Most refs cover both. - Rod57 (talk) 12:41, 2 November 2018 (UTC)

The article lacks context on how exactly the computations/roles were separated between LVDC and AGS

AGS is said to provide "guidance" and LVDC is said to provide "autopilot". The difference has to be postulated clearly in comparison. 93.185.28.160 (talk) 05:54, 7 August 2019 (UTC)

The AGS does absolutely nothing while the Saturn is active. The LVDC takes care of the Saturn from launch to orbit, *then* the AGS takes over. They are two completely separate systems. MrAureliusR_Talk! 19:50, 28 May 2022 (UTC)