From: utzoo!decvax!harpo!seismo!hao!hplabs!sri-unix!GILLMANN@USC-ISIB
Newsgroups: net.micro.pc
Title: Re: XT Async Port Query
Article-I.D.: sri-arpa.1059
Posted: Fri Apr 22 13:15:00 1983
Received: Mon Apr 25 01:54:30 1983

From:  Dick Gillmann <GILLMANN@USC-ISIB>

You're quite right that the BIOS async routine loses characters at
speeds greater than 300 baud.  This is because it just waits for a
character to arrive and then returns it.  If you don't call the
routine often enough, you will lose characters.

To go faster, you have to handle the serial port interrupts yourself.
The PC can handle 9600 baud, but can't quite keep up at 19.2K baud.
I suspect that Basic handles the interrupt itself.

To write your own interrupt handler, you probably want to use
assembler.  But why re-invent the wheel, anyway?  There are lots
of terminal emulator, file transfer and communications programs
for sale at modest prices that do what you want.  Just be sure
they run at 9600 baud before you buy (some don't).  And if you
don't want to spend any money, the Info-IBMPC Free Program Library
has several free ones that you can FTP.

/Dick
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