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Apparently the Dominion ICP runs on uClinux without support for an MMU, and this means that it can only count 4,000ish votes before having to be power cycled. This is really dumb, here's why (thread) sos.ga.gov/admin/uploads/…
Modern computers use lots of memory, and typically rely on memory management to give every program it's own space to do what it needs to do.
This is typically done through virtualization, where the processor tells each process that it has the whole memory space available to it.
To do this, the processor has to keep track of all the processes so that when it gets asked for more memory at location X, it can translate that into a physical location in RAM.
Modern processors rely on a technique called paging to do this, and a specific piece of hardware called a memory management unit to do all the translation for them.
However, it wasn't always this way, and older and low power devices may not have an MMU, as they assume that there's never going to be more than a handful of processes running, and that not that much memory is being used at any one time.
MMUs do incur a bit of overhead, so there's a tipping point where it becomes inefficient to use one. (spoiler: voting machines are not on the side of the tipping point where you shouldn't use one).
Certain operating systems have been developed to support MMU-less processors, notably flavors of Linux like uClinux (used by Dominion's Image Cast Precinct). uClinux also support machine with an MMU, so it's a matter of whether you compile it to use an MMU or not.
Here's the really stupid, absolutely baffling design decision: the Dominion ICP runs on a VIA C7 processor, which HAS AN MMU en.wikipedia.org/wiki/VIA_C7
For some reason, Dominion just didn't compile uClinux to use it. Perhaps their application is written in MMU-less C code or something and they can't be bothered to port it (yay technical debt!)
The result of this is that the OS eats up more and more memory as ballots are scanned in, and, because there's not sophisticated memory management, fragments memory so bad that eventually the machine has to be rebooted before it can scan more ballots.
Fortunately, no ballots are lost in this process, and it is exceedingly unlikely that more than a few thousand ballots will be scanned on one single ICP between power cycles, but nevertheless this is baffling. </thread>
P.S. yes talking about the ImageCast Precinct likely results in lots of confused juggalos.
