Well, on a stock A500, you were limited by the CPU, and the serial.device (Driver), if you used the Commodore supplied Device, then you could not go over 19200 (From memory) without getting errors. But then you had replacement drivers that gave more speed for the basic CPU. (Like Baudbandit.device). I personally had A500 to A500 at 56k, but I am pretty sure there were devices that ran at 115k on a stock A500.
Whao so it was all dependant on CPU power. Back then I kept on relating it to UART FIFO.
haha I remember Baudbandit.device and tried it, but hmm kept on getting drop outs. Come to think of it yes my Ami was unstable above 19k2. Hey coime to think of it what happened to my old Dick Smith Spirit 2 modem, that was a bucket of poo hence the reason I spent $600 AUD on the utlimate USR at the time.
Im happy to know my AMI can achieve high baud rates, just needs a accelerator card

have to try it one day if Im lucky enough to come across a cheapo one.
Serial is as obsolete as my C64, C128, SX64, A1200, A2000, A3000, Mac IIci, Power Mac G3, Archimedes 310, Sun Ultra 2 and some other oldies I have.
Just because it's obsolete, doesn't mean it's not usefull anymore. Hell, we're at Amiga.org here, which is devoted to fully obsolete computers. :-)
Amen! Im still learning things from my Ami but more for hardware design prespective.
haha I got a SGI O2 and SUN LX (Lunchbox) just coz I could and they were cheap back when ppl started to give them up. back in the day I looked up to SGI/SUN machines as if they were the holy grail. I probably thought that way since I was learning *nix in general back then.