Description
The Abort Guidance System included the following components:
- Abort Electronic Assembly (AEA): the computer
- Abort Sensor Assembly (ASA): a simple strapdown IMU
- Data Entry and Display Assembly (DEDA): the interface similar to DSKY
The computer used was MARCO 4418 (MARCO stands for Man Rated Computer) whose dimensions were 5 by 8 by 23,75 inches (12,7 by 20,3 by 60,33 centimeters); it weighed 32,7 pounds (14,83 kg) and required 90 watts of power. Because the memory had a serial access it was slower than AGC, although some operations on AEA were performed as fast or faster than on AGC.
The computer had the following characteristics:
- It had 4096 words of memory. Lower 2048 words were erasable memory (RAM), higher 2048 words served as fixed memory (ROM). The fixed and erasable memory were constructed similarly so the ratio between fixed and erasable memory was variable.
- It was an 18-bit machine, with 17 magnitude bits and a sign bit. The addresses were 13 bits long; MSB indicated index addressing.
- Data words were two's complement and in fixed-point form.
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