Address comments and ideas to dan@landiss.com 
Visit Dan@Work
Not all so-called "diagnostic" programs report the truth about your COMport and IRQ# assignments. The following is a table of data gathered during several tests of available diagnostic software, all applied to the same PC system.
The serial ports were physically set (hardware switches) to COM1/IRQ4, (modem) COM2/IRQ3, and COM4/IRQ5. The BIOS was patched to instruct it to skip the COM3 assignment via the CTSSPU set mentioned below. The bus mouse card is jumpered to IRQ2 which is really only true on an 8-bit (XT) bus. On a 16-bit (AT) bus, that pin is actually physically wired to IRQ9.
| Trouble Shooter (2.02) | IRQInfo Pro (2.0a) | MSD (DOS 6) | QEMM MFT (3.0) | NDiags (NU8.0) | SysInfo (NU8.0) | QAPlus (4.70) | |
| IRQ# | CTS | Microsoft | QDeck | Symantec | Symantec | ||
| 00 | timer | timer | timer | timer | timer | timer | timer |
| 01 | keyboard | keyboard | keyboard | keyboard | keyboard | keyboard | keyboard |
| 02 | cascade | 2nd contr | mouse | mouse | unknown* | mouse | cascade |
| 03 | COM2 | COM2 | COM2&4 | COM2 | not in use | COM2 | COM2 |
| 04 | COM1 | COM1 | COM1&3 | COM1 | Serial 1 | COM1 | COM1 |
| 05 | COM4 | COM4 | - - - | unass'd | Serial 3 | LPT2 | COM3 |
| 06 | diskette | floppy | floppy | floppy | floppy | floppy | floppy |
| 07 | LPT1 | LPT1 | LPT1 | unass'd | not in use | LPT1 | - - - |
| 08 | clock | clock | clock | clock | clock | clock | clock |
| 09 | redirect | mouse | IRQ2 | redirect | - - - | reserved | mouse |
| 10 | - - - | available | - - - | unass'd | not in use | reserved | - - - |
| 11 | - - - | available | - - - | unass'd | not in use | reserved | - - - |
| 12 | - - - | available | mouse | not in use | reserved | - - - | - - - |
| 13 | coproc | coproc | - - - | NCP | coproc | coproc | 80486DX |
| 14 | fixed disk | hard disk | fixed disk | hard disk | hard disk | fixed disk | hard disk |
| 15 | - - - | available | - - - | unass'd | not in use | reserved | - - - |
| *NDIAGS freezes the bus mouse |
As can be seen above, only The TroubleShooter ($200, call 1-800-653-4933) and IRQInfo (Computer Telecommunications Systems; sales@comminfo.com or call 1-800-380-2666 or 1-770-263-8623) correctly identified all the serial ports and their IRQ#s.
CTS also offers the Serial Port Utilities (http://www.comminfo.com) or the Compuserve BENCHMARK forum, Library 8, CTSSPU.ZIP). They include PortInfo which also identifies the serial ports correctly. Only IRQInfo, PortInfo and QAPlus correctly report the mouse card IRQ9. The Norton Utilities, justifiably famous for their disk repair modules, aren't even internally consistent between NDiags and SysInfo when dealing with the rest of the hardware.
Address comments and ideas to dan@landiss.com Visit Dan@Work