I worked extensively on the model before this, the 980B, when I was a flight simulator engineer at Britannia Airways in Luton. One system drove the Boeng 737 simulator, with two Century Data 200Mb (!) exchangeable hard drives.
The other drove the visual system for the Boeing 767 simulator.
I recall using an oscilloscope and stepping through a program loaded into memory and checking the processor registers to look for a lost bit! We even disassembled the boot loader program so we step through it to find a problem. Long ago days!