LEM Lunar Excursion Module, later named LM Lunar Module
Before going into details of the LM control systems lets study the LM construction, parts and subsystems. LM or LEM consisted of two major parts, the descent stage and the ascent stage.
YouTube video: "Anatomy of the Lunar Module"
The following film made 1966 describes well the structure and various internal parts of the LEM lunar module which was build by the Grumman Aircraft Engineering.
"Landing on the Moon" (1966) - Science Reporter TV Series
Contrary to common knowledge LEM carried two computers on board. The main computer was the LGC (Lunar module Guidance Computer) and the AGS (Abort Guidance System) computer. The purpose of the AGS was to run as a backup for the main steering system and it was capable of aborting the LEM alone.
Apollo Lunar Module external parts
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