🚀 go-pugleaf

In article <1991Jun18.201125.6198@cs.cmu.edu>, jch+@cs.cmu.edu
(Jonathan Hardwick) writes: 

> A housemate has an original Big Blue IBM PC, running at the blazing
> speed of 4.77MHz.  We want to use this as a dumb terminal to access
> our university workstations.  The university offers 2400 bps service
> with MNP level 5, and a 9600 bps or 19200 bps MCN service using DOV
> modems.  We'd really like the extra speed if possible.  Is the PC
> going to be able to keep up with 19200 bps?  How about 9600 bps?  

Before coming to Hayes, I worked for Datamaxx USA Corp, writing 
firmware for terminal emulators.  Their biggest-selling product was 
based on a Motorola 6800 processor running at 1 MHz, and supported 
up to 9600bps -- without flow control, and without ever losing data! 
So, I _know_ that a 4.77MHz processor _can_ support 9600, even 
19200, _if_ your comm software is well written.  That's the real 
trick: finding a program that is efficiently written, properly 
supports flow control, scrolls fast, properly schedules writes to 
disk to avoid slowdowns, etc.  Hayes Smartcom Exec is one such 
program (its what I use), but I'm sure you can get plenty of 
recommendations for good programs that can keep up with 9600 or 
19200 on a 4.77 MHz PC.

If you're doing anything fancy on the PC (running TSRs that hook 
into the timer interrupt, or a LAN card, or RAMdisk), then you may 
want to invest in a buffered serial port card like Hayes ESP.  This 
provides 1024 bytes of buffer in the hardware, plus automatic 
hardware flow control, so even if the main CPU gets a bit behind 
tending to other things, you still don't lose characters.  It's a 
lot cheaper and easier than getting a new motherboard, assuming 
you're using a modem that has flow control.

So, anyway, my advice is, "go for it".

-- 
Toby Nixon, Principal Engineer    | Voice   +1-404-840-9200  Telex 151243420
Hayes Microcomputer Products Inc. | Fax     +1-404-447-0178  CIS   70271,404
P.O. Box 105203                   | UUCP uunet!hayes!tnixon  AT&T    !tnixon
Atlanta, Georgia  30348  USA      | Internet       hayes!tnixon@uunet.uu.net