> From: Stephen Leake [mailto:[log in to unmask]]
> Sent: Thursday, February 07, 2002 6:33 AM
>
> Ah, the luxury of having the bandwidth to upload the entire code set
> :).
>
> I never had the experience directly, but apparently in the Bad Old
> Days you could not do that, and had to upload the smallest possible
> patches. Actually, some of my current missions still plan to operate
> in that mode.

We still operate that way due to limited contact time with our birds.
"Patchability" can become a driving factor in the software design and
tool selection.  Rational Software has a "patch linker" which supports
small code patches.  Similar tricks can be performed with GNU tools.

Changes to data structures present the biggest problem when patching
flight software.  Ada provides a lot of options (access functions,
reserving space with 'Size rep clause, etc.), but the safest approach
seems to be uploading a new flight image (which may require multiple
orbits).