3 hours ago
After you left I had to look up the SIO technical specs, and you were right about the Happy speeds being faster than 19.2k. It's spec'd as running at 52k. The SIO has a theoretical speed of 120k, but you have to remove two capacitors and add a resistor in order to unlock that speed. It was originally capped at 19.2k because of two things: 1) the FCC putting a limit of how much interference was allowed and 2) Atari at the time didn't have any equipment that could handle speeds faster than 19.2k and therefore weren't able to measure interference above it. But the coolest thing was the 6532 MOS chip in the drive was called the RIOT (Ram In/Out Timer)...