engle@wdl1.wdl.loral.com (David Engle) (04/11/91)
I have a shortage of COM ports on my 386SX system. I'd like to ask the net's help to see if I can "fix" the problem. The system: 386SX-16, Award Bios V3.11, C&T chip set, SVGA, etc., running DOS 4.01 (and on occasion Windows3). The problem is I need three fully functional, separate com ports. The "normal" approach seems to be to assign the IRQ for com1 to com3 when com3 is present, with the expectation that the two comm ports will share the IRQ. Com1 is where my mouse is and Windows will not allow me to multiplex that IRQ. I have also tried sharing com2 and com4 on the same IRQ and that does not work either. I have tried to utilize an IRQ normally utilized by LPT for com3 and I have tried to utilize IRQ2 (which is the chained expansion interrupt for AT class PCs). Neither of these approaches works. It appears that the problem is in the driver assignments to the IRQ addresses. That is, my PC expects comm interrupts only on the "normal" comm IRQs, any attempt to fool it fails. An individual I know says that a more recent version of the BIOS will allow multiple non-shared comm ports. This guy's advice is somewhat suspect, as he has trouble figuring out the on-off switch. So....Is what I need a new BIOS chip set? Or does anybody know of any ather approaches that will work? A rational alternative could be to get a bus mouse (thus freeing up my 2nd comm port). However, I need to know that I can assign its IRQ to someplace out of the way (like a printer IRQ). Can anybody tell me what bus mouse you have and what IRQ range it (by product) can be set to? Thanks in advance, Dave engle@wdl1.wdl.loral.com -- David Engle, KE6ZE - engle@wdl1.wdl.loral.com - 408/473-4419 @ work Facts, what facts? I don't got to show you no stinking facts. These are opinions expressed here.
jrd@cc.usu.edu (04/14/91)
In article <1991Apr11.161906.23360@wdl1.wdl.loral.com>, engle@wdl1.wdl.loral.com (David Engle) writes: > I have a shortage of COM ports on my 386SX system. I'd like to ask > the net's help to see if I can "fix" the problem. > > The system: 386SX-16, Award Bios V3.11, C&T chip set, SVGA, etc., > running DOS 4.01 (and on occasion Windows3). > > The problem is I need three fully functional, separate com ports. > The "normal" approach seems to be to assign the IRQ for com1 to > com3 when com3 is present, with the expectation that the two comm > ports will share the IRQ. Com1 is where my mouse is and Windows > will not allow me to multiplex that IRQ. I have also tried sharing > com2 and com4 on the same IRQ and that does not work either. > > I have tried to utilize an IRQ normally utilized by LPT for com3 > and I have tried to utilize IRQ2 (which is the chained expansion > interrupt for AT class PCs). Neither of these approaches works. > > It appears that the problem is in the driver assignments to the > IRQ addresses. That is, my PC expects comm interrupts only on the > "normal" comm IRQs, any attempt to fool it fails. An individual > I know says that a more recent version of the BIOS will allow multiple > non-shared comm ports. This guy's advice is somewhat suspect, as he > has trouble figuring out the on-off switch. > > So....Is what I need a new BIOS chip set? Or does anybody know of any > ather approaches that will work? > > A rational alternative could be to get a bus mouse (thus freeing up > my 2nd comm port). However, I need to know that I can assign its IRQ > to someplace out of the way (like a printer IRQ). Can anybody tell me > what bus mouse you have and what IRQ range it (by product) can be set to? > > Thanks in advance, Dave engle@wdl1.wdl.loral.com > > -- > David Engle, KE6ZE - engle@wdl1.wdl.loral.com - 408/473-4419 @ work > Facts, what facts? I don't got to show you no stinking facts. > These are opinions expressed here. ----------------------- Dave, First, DOS and the Bios don't use interrupts (and hence IRQs) for the serial ports, but applications programs can. One cannot have today's typical serial boards placing two serial ports on the same IRQ line, so something will have to move. A common solution is to a) think about how many serial devices are really used simultaneously (typ two) then b) purchase an ABCD box for $30 and place it on one port. Some serial port boards permit assigning a port to IRQs other than 4 or 3. The current MS-DOS Kermit v3.10 comms program, and I believe Procomm, let you tell the program which IRQ you wish to use with a port. Another alternative is to purchase a parallel to serial converter box (see back pages of BYTE) and hang your serial printer (I'm guessing here) on that to the computer's parallel port. Easier than fighting City Hall. Joe D.
tar@pa.reuter.COM (Dan Tarnower) (04/16/91)
I believe tahhat the PS/2 family has a redesigned COM port which allo multiple ports to share a single IRQ line. I also remember reading about a new serial card that does the same thing, but I don't have any details. This hardware ability is fine, but unless all ISR's on the same IRQ know that they may be sharing the line, I doubt if it will work. /Dan Tarnower