On 9/20/2015 10:21 AM, Marlon Ng wrote: > I forgot to mention. The pci parallel expansion is a 3-in-1. It has > one parallel, and two serial (I think). Could this be the reason why > the computer sees it as LPT3? If so, how do I change it to LPT1? I > can't see anything in BIOS that would allow me to do that (?). I've > also read about CMOS being different from BIOS, but I don't know how > to get in there. No, I used hundreds of 3-in-1 cards "back in the days". I did have many machines with 3 (or even 4) parallel ports, 3-8 serial ports.
But which "LPT" port DOS (and hence a program running on DOS) sees depends on where the BIOS is entering the base port address in that BIOS data segment address I mentioned put. Contrary to common belief, there is no fixed port addresses associated with a specific LPT port (or COM port for that matter). The originally IBM PC BIOS was scanning for ports in a specific order and that is what most other manufacturers followed. "Standard" parallel port used to have 378h and 278h, which were assigned to LPT1 and LPT2 (if present) from high to low. That meant that the add-on parallel port on a Hercules (and compatible) video adapter, which was fixed at port address 3BCh, became LPT1 when added to a PC (which meant that an otherwise present parallel port on 378h, which would have been assigned to LPT1 in case without the Hercules card, now would be LPT2). So if you have a program that works only with LPT1 (and not with a hard coded base port address!) will use what ever address is put into 0040:0008. You can change that address to match what your expansion card is using either by using debug (-e 0040:0008) or one of the many port changing programs that used to be around for just that purpose... Ralf --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------ _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
