I have used a BASIC program to test the baudrates.

10 REM test transmission baudrates
20 BDR = &HFB27
30 REM Baudrate Value
40 REM 1200     170
50 REM 2400     83
60 REM 4800     39
70 REM 9600     17
80 REM 14400    10
90 REM 19200     6
100 REM
110 POKE(BDR),17
120 LPRINT "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG 01234567"
130 LPRINT "the quick brown fox jumps over the lazy dog !@#+-()."
140 GOTO 120

The code worked in all speeds with the given values for the delay loop. but I have tested some values around and verified that above 9600 bauds such value is very critical.