The SID chip (if clocked at 1MHz) samples its POTX, POTY lines every 512us. It does this by discharging each POTx line's capacitor to ground for 256us, then floats the line for another 256us. A corresponding counter increments monotonically until the voltage across the capacitor exceeds 2.5V.
The mouse starts out by floating its POTx outputs high, waiting for the SID to bring POTX (specifically) low. When this happens, the mouse then drives the POT line low and waits for 320us to elapse, making sure to exceed the 256us sync window.
It then waits an additional 0 to 127 microseconds depending on the coordinate it wants to send. The mouse then drives the POT line high for a microsecond or two, slamming the capacitor in the computer to 5V. This also freezes the A/D counter, since it exceeds the 2.5V threshold.
After that procedure, the mouse floats its output again, knowing that the POT line is once again in a state where it can detect the SID chip's synchronization pulse, and the process starts all over again.
This means that, on each POT line, 7 bits of data are transferred every 512us, for an equivalent serial data rate of 13671.875 bits per second. There are two POT lines in operation at the same time, for a total data rate of 27343.75 bps.
Not too shabby!
I'm leaving Google with a bitter smile 💔
@codewiz @patrick @lubimaer @5tr34k_ @ilwoody it looks like this is a thing people are working on: https://github.com/WebOfTrustInfo/rwot9-prague/blob/master/topics-and-advance-readings/fediverse-did-integration.md I'm skeptical as to whether that many users would actually use this though since it'd almost certainly be more involved than the status quo of creating an account on an instance.
already 2 years old, but amazing blog post on reverse-engineering physical geomery of hard disks using micro bench marks: https://blog.stuffedcow.net/2019/09/hard-disk-geometry-microbenchmarking/
Landed. And passed through US immigration without showing a passport or other ID: just face recognition 😨
Today I'm relocating to #LosAngeles and looking for long-term housing.
I have zero friends in LA. Any fedinauts living around here?
🇮🇹 → 🇺🇸 → 🇯🇵 → 🇹🇭 → 🚀
Nomadic Linux developer, currently in Los Angeles.
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