would be pretty simple for the programmer/engineer to know this is a limitation of the device based on just theory since presumably the axle count is being stored in 16 bits with 0 as the "clear" state
See, that's what I would have assumed. But the wording of "exactly 256 axles" instead of "no more than 255" makes it sound like you can have more, just not that specific number (assuming there isn't nuance lost in the translation...)
nah the counter is probably designed to just loop (maybe it's mechanical or a primitive counter made of AND and OR gates) and only ever signals clear when 0'd, with some method for the end of the train to trigger the zeroing, so you'd theoretically have a false signal during the 256th axle...
i think they recently removed this rule
it's also important to know that the rule didn't really matter because trains weren't allowed to be longer then 750m which is about 200 axles
yeah. i mean it took huge infrastructure projects for the swiss railways to consider longer trains than 750m so i assume back when they installed the system they thought an 8bit counter would be fine for a long while
😂👍 And yet, just over 25 years ago, as we desperately tried to avoid the world's computer systems going haywire, people were sneering at us that 'the millennium bug' wasn't real ..
considering it is as small as 8-bit, it is probably a very old, entirely hardware/electrical counter. No software involved, all on chip.
And probably not a bug, but a known limitation of the design, and for cost/performance reasons they cover the limitation socially rather than complicate the chip
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so only every n256 axles are a problem case
it's also important to know that the rule didn't really matter because trains weren't allowed to be longer then 750m which is about 200 axles
And probably not a bug, but a known limitation of the design, and for cost/performance reasons they cover the limitation socially rather than complicate the chip
Swiss people are notoriously paranoid. e.g. they have two completely redundant municipal water systems in much of the country.
easier to regulate the existence of exactly 256 axles than do a sweep to fully decommission any 8 bit counter installed somewhere