Details on Spirit Breakdown

(Eric Chomko) writes:

Scratchpad RAM, at least, to work with the ROM will also be needed.

JPL said at a briefing that the MERs have 256 MB flash RAM, 128 MB
dynamic RAM, and some EEROM. And they said the images are stored in
flash. They didn't mention unerasable ROM or rotating disks. So the
latter seems very unlikely, but I wouldn't want to bet on the former;
it *might* be used for bootup code or math tables or even one version
of the OS. They said they can boot up without using the flash and,
IIRC, they said they have a couple of copies (or versions) of the OS.
I'm guessing that boot code in EEROM copies the OS from EEROM to DRAM
and boots it from DRAM. There is probably a hardware gizmo to cause a
second copy/version of the OS to be booted if the first one doesn't
work well enough to play with the gizmo properly, etc...

The long and short of the Spirit debacle: Test what you intend to
do, and Do what you tested for. In the lab, they tested for 9 days
at a time, then cleaned things up, and ran again.

Ugh, another short of it would be: don't have tight margins when
bigger margins are cheap.


-Lex