DF-224

As with many spacecraft computers, the design is very redundant, since servicing in space is at best difficult and often impossible.

[2] The processor used fixed-point arithmetic with a two's complement format.

[3] The DF-224 on HST was augmented with a 386 co-processor on the first servicing mission (SM1).

[4]: fig 7-3 In Hubble servicing mission 3A the DF-224 (with co-processor) was replaced by the Advanced Computer using a 25 MHz Intel i486, and much more storage[4]: 1–7 The DF-224 was one of the candidate computers for the Space Shuttle, but was not selected.

[5] It was also baselined in a version of a reusable Agena upper stage for use with the Shuttle,[6] but this was never built.