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From: wutcd@chemnitz.guug.de (Joerg Wunsch)
Newsgroups: comp.unix.bsd
Subject: Re: How do I enable COM3 and COM4?
Message-ID: <wutcd.719854141@hadrian>
Date: 23 Oct 92 15:29:01 GMT
References: <veit.719567281@du9ds3> <1992Oct15.014800.729@skitzo.dseg.ti.com> <1992Oct15.162922.24566@fcom.cc.utah.edu> <1992Oct19.032151.29724@cs.cornell.edu> <1992Oct22.111534.17570@rdg.dec.com>
Sender: bin@hrz.tu-chemnitz.de (Owner of all binaries)
Organization: tu-chemnitz
Lines: 41
franzoni@sixter.var.dec.com (Mauro Franzoni) writes:
>> >>In article <1992Oct15.014800.729@skitzo.dseg.ti.com>
>dittman@skitzo.dseg.ti.com (Eric Dittman) writes:
>|> >>>How do I enable COM3 and COM4 in the binary distribution of 386BSD 0.1
>|> >>>from agate.berkeley.edu? Or do I have to do this from the source?
>|> >>
[[[dont' wanna repeat too much here]]]
>|> works for me". In real situations, it will fail miserably.
>Yes, it fails - and block all of /dev/com0[1-4]
For those who really do use that $10-style i/o cards (_NOT_ recommended
for on-board com ports), and who are able to use a solering iron, there
could be another simple solution which is really cheap and doesn't re-
quire software patches:
Scratch out the original IRQ lines from the additional PCB (or, if you
can do so, remove all IRQ jumpers), then either:
- if you don't have a second line printer port, nor any ethernet card,
you should be able to connect the IRQ outputs to IRQ5 (reserved for
LPT2), or IRQ2 (reserverd for EGA vertical retrace, but seldom used;
or for network adaptors) resp.
- build a dummy plug for the extension slot of ISA bus (simple i/o cards
are normally only 8-bit wide), and use one of the unused IRQ's from AT's
secondary interrupt controller (PIC), only IRQ 13 (npx0) and IRQ 14
(hard disk) are used, sometimes (SCSI controller) even IRQ 11. All
the other ones are available! What a waste inserting another slave
PIC... The PIC handling for secondary PIC is done in locore.s (or so)
depending on the IRQ level, so you don't need to care for (unlike
with DOS s/w, such as mouse drivers which surely won't work on second-
ary PIC).
Dont't blame me for any damaged boards;-) it's your own risk, of course.
J"org
--
J"org Wunsch, TCD GmbH Dresden, R"ahnitzgasse 18, D-O-8060 Dresden
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