The port address can be any of the following: $278, $378, $3BC.
Monochrome video adapters usually have a parallel port hard wired at $3BC.
If you have more than one parallel port, the BIOS assigns LPT numbers to them from highest to lowest. For example, if a system has ports at $3BC and $278, LPT1=$3BC and LPT2=$278.
Printer ports are set to IRQ 7 in about 85% of cases; the other 15% is IRQ 5.
It is usually safe to share the IRQ with another peripheral, as the IRQ line on the parallel ports are almost NEVER actually used (even while printing).
When in doubt, tell your software you have a Sound Blaster Pro at the following settings: Port $220, IRQ 5, DMA 1, High DMA 5. If this doesn't work, try a regular Sound Blaster at Port $220, IRQ 7, DMA 1. This will work most of the time. If not, updated drivers may be available for your software. Unfortunately, some programs simply refuse to work with some sound cards at any settings; but this is pretty rare.
|1||Keyboard||Not currently, but maybe when USB catches on|
|2||Slave to 9||Linked with 9|
|3||COM2,COM4||If you don't have these COM ports, it's probably free|
|4||COM1,COM3||Same as for IRQ3.|
|5||Soundcard, parallel port||Rarely|
|7||Printer||Can usually be shared sucessfully|
|9||MPU-401||Sometimes; the MPU-401 on your soundcard can often be disabled|
|12||PS/2 Mouse||Usually in clones, rarely in retail systems|
|13||Math co-processor||Very Rare|
|15||Primary IDE||Only in XT or SCSI only systems|
|$220||Sound card digital audio|
|$388-$38B||FM synthesis (music)|