jzitt@dasys1.UUCP (Joe Zitt) (05/08/89)
Is there a way to fake out a PC into talking to a different COM port?
Here's the situation: I have what looks like a really neat Unix Mail clone.
Unfortunately, the code is hard-wired to use COM1:. Since my )!(@*#&$^% MIDI
board is also hard-wired to COM1:, I had to put my modem on COM2:.
Is there a way to get the software to talk to the other port, either through
a small resident or something else?
--
Joe Zitt * {sun!hoptoad,cmcl2}!dasys1!jzitt * Big Electric Cat
PAM Repertory Company also: (killer,uunet,psuvax}!cbis3!elephant!zitt!joe
imagine the clouds dripping. dig a hole in your garden to put them in. yoko '83nelson@sun.soe.clarkson.edu (Russ Nelson) (05/09/89)
In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) writes:
Is there a way to fake out a PC into talking to a different COM port?
Yes and no. Due to the lack of of interrupt driven COM port service
in the BIOS, everyone directly accesses the 8250. So the only way to
do what you want is to patch your program to use the different COM port.
This can be non-trivial.
--
--russ (nelson@clutx [.bitnet | .clarkson.edu])
I'm a right-to-lifer -- everyone has a right to earn a living sufficient to
feed himself and his family.posert@bonnie.ics.uci.edu (Bob Posert) (05/09/89)
In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) writes: > > Is there a way to fake out a PC into talking to a different COM port? > Part of the Baker's dozen utility set is a program called swcom12.com. I haven't tried it, but the documentation is: } SWCOM12.COM } ----------- } Switch RS-232 ports for COM1 and COM2. No parameters. } } To start: } C>swcom12 I'd post, but the package has to be distributed as a whole. Bakers Dozen is shareware, so you might be able to find it on a local bbs, or you can contact the author(?)/distributor directly at: Jim Button P.O. Box 5786 Bellevue, WA 98006 1-800-JBUTTON. -- Bob Posert I'm: posert@bonnie.ics.uci.edu or {sdcsvax|ucbvax}!ucivax!bonnie!posert
tkopp@carroll1.UUCP (Tom Kopp) (05/09/89)
In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) asks: >Is there a way to fake out a PC into talking to a different COM port? The dos assign command should work. I've seen it used to tell something to send to COM1 everything that was supposed to go to lpt: so your mileage may vary. Basically, before you are going to use the modem, enter the following line: assign com1 = com2 If this doesn't work, reverse the com1 and com2. I haven't used the command for a long time, so.... -- tkopp@carroll1.cc.edu or uunet!marque!carroll1!tkopp Thomas J. Kopp @ Carroll College 3B2 - Waukesha, WI
aiko@cs.odu.edu (John K Hayes) (05/09/89)
In article <412@carroll1.UUCP> tkopp@carroll1.UUCP (Tom Kopp) writes: >In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) asks: >>Is there a way to fake out a PC into talking to a different COM port? > >The dos assign command should work. I've seen it used to tell something to >send to COM1 everything that was supposed to go to lpt: so your mileage may >vary. > >Basically, before you are going to use the modem, enter the following line: > >assign com1 = com2 > >If this doesn't work, reverse the com1 and com2. I haven't used the command >for a long time, so.... > > >-- >tkopp@carroll1.cc.edu or uunet!marque!carroll1!tkopp >Thomas J. Kopp @ Carroll College 3B2 - Waukesha, WI I was having the same problem with a Zenith 248 that came with a funky adaptor that plugged into one of the bigger ports on back and had two ports on the other side of it - I forget the specifics, but the effect was that with the adaptor, the modem could not be plugged into COM1 but only COM2 which was on the back of the adaptor. Anyway, I tried the DOS assign command and I believe that command is only useful for assigning a COM port to an LPT port and possibly vice versa. It did not work assigning one COM port to another COM port. I ended up yanking the stupid adaptor off of there. -- ---{john hayes} Old Dominion University; Norfolk, Virginia USA internet: aiko@cs.odu.edu Home: (804) 622-8348 Work: (804) 460-2241 ext 134 <++++++++++++++++++++++++++++++++++> Are you a Have or a Have_Not? Because if you're a Have_Not, you've probably had it; whereas, if you're a Have, you've probably got it and are going to give it away at some point in the future! --- The Clash <++++++++++++++++++++++++++++++++++>
hollen@eta.megatek.uucp (Dion Hollenbeck) (05/10/89)
From article <412@carroll1.UUCP>, by tkopp@carroll1.UUCP (Tom Kopp): > In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) asks: >>Is there a way to fake out a PC into talking to a different COM port? > > assign com1 = com2 > If this doesn't work, reverse the com1 and com2. I haven't used the command > for a long time, so.... Yes, this will work, but only with programs which ask DOS to provide COM service. The majority of programs talk directly to the UART and this would be of no use with those programs. Dion Hollenbeck (619) 455-5590 x2814 Megatek Corporation, 9645 Scranton Road, San Diego, CA 92121 seismo!s3sun!megatek!hollen ames!scubed/
network@mstr.hgc.edu (craig chaiken) (05/10/89)
In article <412@carroll1.UUCP>, tkopp@carroll1.UUCP (Tom Kopp) writes: > In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) asks: > >Is there a way to fake out a PC into talking to a different COM port? > Basically, before you are going to use the modem, enter the following line: > assign com1 = com2 MSDOS's ASSIGN command reassigns block devices (disk drives), not character devices such as COM1. Use the command MODE COM1=COM2 to make COM1 be COM2. You can also achieve this effect by copying the word at address 0000:402 to 0000:400. Craig Chaiken Hartford Graduate Center Computing Services network@mstr.hgc.edu
rayd@laidbak.UUCP (Ray Dueland) (05/10/89)
You could change the binary. Load the program with debug and search for
all occurrances of the IN and OUT instructions. Change the ones that
operate on the COM1 addresses (3f8?) to operate on the COM2 addresses.
The only other thing I can think of that would need to be done is to
change where the interrupt vector gets loaded.
--
Ray Dueland
{amdahl|clout|masscomp|nucsrl|sun|tellab5}!laidbak!raydtj@gpu.utcs.utoronto.ca (Terry Jones) (05/10/89)
Even programs that go directly to hardware may work with the "switched" com ports. There is an area in memory that stores the hardware addresses of installed ports (40:0) and software that actually looks there to find the address of com1 or 2 should switch properly. In this guy's case maybe he will get lucky in that ONE and ONLY ONE of the programs he wants to use with com1 will look at the address to find where the hardware is and go there and if they are switched then it will access com2, now if the other program just goes to hardware at com1 address then they will behave! tj
cb@cci632.UUCP (Just another hired gun (n2hkd)) (05/11/89)
In article <412@carroll1.UUCP> tkopp@carroll1.UUCP (Tom Kopp) writes:
.In article <9593@dasys1.UUCP> jzitt@dasys1.UUCP (Joe Zitt) asks:
.>Is there a way to fake out a PC into talking to a different COM port?
.
.The dos assign command should work. I've seen it used to tell something to
.send to COM1 everything that was supposed to go to lpt: so your mileage may
.vary.
.
.Basically, before you are going to use the modem, enter the following line:
.
.assign com1 = com2
^^^^^^^^^^^^^^^^^^^^
Gee that's what I thought, however they gone and changed this
again. According to my Compaq 3.2 manual, they assign command
is only available for a "specific drive" to a "different drive".
The Mode command can reassign, but only the printer ports!!
Looks like they decided that we don't need that feature anymore...
--
my signature file just got squashed......................
email: cb@cci632 or !rochester!kodak!n2hkd!curtis
Curtis Braun, Computronics, PO Box 1002 Fairport NY, 14450 gordon@eecea.eece.ksu.edu (Dwight Gordon) (05/11/89)
In article <1989May10.111641.8831@gpu.utcs.utoronto.ca> tj@gpu.utcs.UUCP (Terry Jones) writes: >Even programs that go directly to hardware may work with the "switched" >com ports. There is an area in memory that stores the hardware addresses >of installed ports (40:0) and software that actually looks there to find the >address of com1 or 2 should switch properly. . . . The problem comes if your software uses interrupts. Normally COM1 is hard-wired to INT4 and COM2 is hard-wired to INT3. Swapping the pointers will fool the bios into believing that the hardware COM1 is really COM2 and visa-versa, however the interrupts will remain the other way around. This will cause any (well, almost any :-) software to be confused. Theoretically, the software could look for standard port assignments, and make some assumptions if they are not so, but this is a lot to expect of any programmer :-) (no flames please, I program too!). Dwight W. Gordon | 913-532-5600 | gordon@eecea.eece.ksu.edu Electrical & Computer Engineering Department | dwgordon@ksuvm.bitnet Kansas State University - Durland Hall | rutgers!ksuvax1!eecea!gordon Manhattan, KS 66506 | {pyramid,ucsd}!ncr-sd!ncrwic!ksuvax1!eecea!gordon
donp@bucket.UUCP (Don Park) (05/12/89)
> > Is there a way to fake out a PC into talking to a different COM port? > One way would be to use BNUCOM - a Level 5 compatible F.O.S.S.I.L. driver. It comes with a utility to change BNU's com addresses to effectively use different ports without changing the program. (Assuming this program uses a fossil driver) Hope this helps, Don -- +------------- Bark Technologies - Don Park - Bryan Bybee ------------------+ : BBS (503)-257-3666 - VOICE (503)-246-0025 - (503)-256-2195 - Bark Tech. /\ : : Hardware - Software - IBM - TANDY COLOR COMPUTER - Support - Tech. Line \/ : +----------------- ...!tektronix!teksce!bucket!donp --------------------------+