3 ms·
Really interesting comment from the linked article by one of the Acorn developers, Paul Fellows: ... we had one of the machines that we just could not get this
by joosters 6y ago
Really interesting comment from the linked article by one of the Acorn developers, Paul Fellows:
... we had one of the machines that we just could not get this thing to boot reliably. You could boot it, turn it off, reboot it and sometimes it would work and sometimes it wouldn't. It turned out, it would boot fine if you left it long enough, but if you didn't turn it off for very long then it didn't reset properly, and this was because the fan on the board was still spinning and the back EMF on the fan was enough power to keep the ARM running. And that's why you've got an ARM in your phone today, it would take no power to keep a 3 micron ARM with 25000 transistors would run for 30 seconds off the energy stored in the fan.
- rsecora 6y agoOoops. I used PACE based STB by 2002 and they had booting problems. I have blame the OS for 18 years. But that explanation about EMF makes sense.
- timthorn 6y agoPaul is one of the lesser known players in the Cambridge tech story, and deserves greater recognition.
- guenthert 6y agoAnd the CPU is the only part being powered by that fan. Never mind the voltage regulators 12V, 5V (or were the 3u ARM already 3V3?)... Seems to be a sport among the distinguished engineers to take the kids for a ride.
- marshray 6y agoWell the fan could have been downstream of the 5V regulator... but I agree that this story is pushing the limits of plausibility. Generally fans are a very effective way of dumping energy, not storing it. They're literally used for this purpose in exercise bikes.