On 2025-02-11 9:32 a.m., Peter Corlett via cctalk wrote:
The proper solution to dodgy PC serial port performance was of course to upgrade to the 16550 which had a FIFO which could buffer a few bytes while the PC got round to answering the interrupt. It's not the greatest UART and adds novel failure modes, but it does have the extremely useful property that it is register-compatible with the 8250 and so older software can still drive it without needing to be patched.
I thought many 16550 had dud fifo's. Interrupts under DOS was hit and miss.
The 16550 (at 1.8432Mhz) still has the same top speed of 115,200 baud, but that's just fine for the kind of applications which use physical RS-232-compatible serial ports such as dialup modems and serial mice. RS-232 only guarantees up to 20 kilobaud anyway, and anything faster is out of spec and works through luck. Fortunately, we had a lot of luck by the late 1990s when V.90 dialup came around. Want to go even faster over long cable runs? We have Ethernet for that sort of thing, and it's rather more reliable at it.
Sneaker net with van is better yet, moving large data.(10 TB per tape) :).
