Technical information

Serial Solutions NewBIOS Reference
IRQ NORMAL USE COMMENTS STATUS
2 VGA GRAPHICS CARD Used by very few VGA cards Usually OK
3 COM2 Dedicated to COM2 at 2F8hex COM 2 ONLY
4 COM1 Dedicated to COM1 at 3F8hex COM 1 ONLY
5 LPT 2 DOS/WIN don’t use this IRQ Good in DOS
Avoid with OS/2 Novell WinNT & Windows
6 FLOPPY DISK Dedicated to Floppy Disk AVOID !!!
7 LPT 1 DOS/WIN don’t use this IRQ Good in DOS
Soundblaster Avoid with OS/2 Novell WinNT & Windows
10 Usually Free Recommended for COM3 GOOD
11 Usually Free Recommended for COM4 GOOD
Adaptec SCSI if not Adaptec SCSI card
12 POINTING DEVICE Free if Mouse is on COM port Usually OK
14 IDE HARD DISK Usually In Use. Usually BAD
Free when SCSI disks in use
15 Usually Free Recommended GOOD
0 Timer Tick, 18 per second, not on expansion bus CAN’T USE
1 Keyboard interrupt, is not on expansion bus CAN’T USE
8 Real Time clock interrupt, not on expansion bus CAN’T USE
9 Best left unexplained, is not on expansion bus CAN’T USE
13 Maths coprocessor int, not on the expansion bus CAN’T USE
Each serial port needs its own interrupt line for trouble free
performance, if two serial ports are allocated the same IRQ line
only one can use it at any time. NewCOM allows one port to
use the IRQ line, and any others allocated that line are polled.
For DOS and Windows 3.x use, after COM1 and COM2
installed, then IRQs 5, 7, 10, 11, 12 and 15 are available.
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