16450 was the one with buffer issues
On February 11, 2025 11:49:23 AM EST, ben via cctalk <cctalk@classiccmp.org> wrote: >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) :). > >
