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>... hardware that is 100 million miles away is an interesting experience. Having a read-eval-print loop running on the spacecraft proved invaluable in finding

by na85 10y ago

>... hardware that is 100 million miles away is an interesting experience. Having a read-eval-print loop running on the spacecraft proved invaluable in finding and fixing the problem So... How exactly does it work to have a repl on the spacecraft? Doesn't the system halt while it's waiting for user input?

zengid 10y ago
Not the author, nor an expert, but I'm guessing it could be setup so that the 'OS' throws and interrupt when it receives a transmission signal requesting the REPL process [1]. So whatever normal processes that the device needs to run would get paused by the interrupt signal, and the REPL process would start up. [1] https://en.wikipedia.org/wiki/Operating_system#Interrupts https://en.wikipedia.org/wiki/Operating_system#Interrupts
gkya 10y ago
You can check how SLIME [1] works to get an idea of that. [1] https://common-lisp.net/project/slime/ https://common-lisp.net/project/slime/
lisper 10y ago
No. We used a multi-threaded Lisp. One thread ran the REPL, and other threads ran the RAX code.