*BSD News Article 71811


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Modem at COM3: can't find it!
Date: 23 Jun 1996 13:41:02 GMT
Organization: Private BSD site, Dresden
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  <31C6C2FF.26FB@www.play-hookey.com>
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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Ken Bigelow <kbigelow@www.play-hookey.com> wrote:

> Not true! MeSsy-DOS recognizes four specific port addresses for serial 
> ports in order: 0x3F8  0x2F8  0x3E8  0x2E8
> 
> However, MacroSquish in their (?)wisdom still left only the two IRQ lines 
> specifically allocated to COM ports.

Not that i really like to defend M$, but that's rather the fault of
Little Blue's geniusses of engineers.  They've been to stingy to use a
tri-state gate for driving the IRQ line, which would have allowed for
shared interrupts, but yet assigned the default IRQs for com1/com3 and
com2/com4 twice.

These funny engineers did more things one could damn them now, like
dropping the READY line from the floppy bus, just for the sake of
their $%@!ing ``twist some lines to change the drive ID'' misfeature.
So now, you don't know whether there's a floppy in the drive without
trying to read something, and having the controller timeout if no
floppy was there (which in turn gets the FDC stuck where only a hard
reset will unwedge it).

There's also the 16-bit DMA controller which is another indication of
their unlimited wisdom...

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)