Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!thyme!kaleb
From: kaleb@thyme.jpl.nasa.gov (Kaleb Keithley)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Setting BAUD rate with MODE command
Message-ID: <1991Jan9.174511.19295@thyme.jpl.nasa.gov>
Date: 9 Jan 91 17:45:11 GMT
References: <1991Jan9.003303.18953@thyme.jpl.nasa.gov> <1991Jan09.150149.15065@cpqhou.uucp>
Distribution: na
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 36

In article <1991Jan09.150149.15065@cpqhou.uucp> randys@cpqhou.uucp (Randy Spurlock) writes:
>
>I hate to be picky, but since I developed the mode command for MS-DOS 3.0
>and programmed BIOS ROM's, I have to take offense! If you would read the
>data sheet for the Intel 8250, the original asynch. chip used in PC's, you
>would have seen that the data sheet said the baud rate generator was only
>good up to 9600 baud, even though you could program it up to 115.2 Kbaud,
>and my experience is that 19.2 Kbaud works on every machine I have tried.
>But to be fair to us "brain-dead" BIOS coders we simply followed the data
>sheet recommendations and only supported up to 9600 baud :)!
>

Asbestos suits on folks...  I smell a flame fest.

Lighten up!  I never said the people who implemented were brain-dead; maybe 
you were looking for something that wasn't there?  Just for the record, I 
did read the Intel data sheet (over five years ago), in fact that's how I 
figured out that I could make the 8250 work at 19200...  (It certainly
wasn't because of anything in the IBM PC BIOS listings.) 

It is my opinion though, that cramming every parameter into a single
register was a tad short-sighted.  Jeez, you left at least two registers 
unused.  Might it not have made more sense to use BX for the baud and CX 
or DX for the stop bits and parity bits....  Also, when you look at the
code in MODE, to pack the data into one register, and the code in the BIOS
to unpack the register...  (And people wonder why companies like Lotus
circumvent DOS and BIOS to squeeze every last little bit of performance
out of their product.)  Then, when technology advanced a little bit 
(God forbid technology should advance) then you wouldn't be hamstrung 
trying to be backwards compatible?  Isn't hind-sight wonderful?

-- 
Kaleb Keithley                      Jet Propulsion Labs
kaleb@thyme.jpl.nasa.gov

Offensive quote coming soon to a .signature file near you.