Microsoft KB Archive/61806

= BIOS Equipment-List Word =

Article ID: 61806

Article Last Modified on 11/16/2006

-

APPLIES TO


 * Microsoft MS-DOS 3.1
 * Microsoft MS-DOS 3.2 Standard Edition
 * Microsoft MS-DOS 3.21 Standard Edition
 * Microsoft MS-DOS 3.3 Standard Edition
 * Microsoft MS-DOS 3.3a
 * Microsoft MS-DOS 4.0 Standard Edition
 * Microsoft MS-DOS 4.01 Standard Edition
 * Microsoft MS-DOS 5.0 Standard Edition
 * Microsoft MS-DOS 5.0a
 * Microsoft MS-DOS 6.0 Standard Edition
 * Microsoft MS-DOS 6.2 Standard Edition
 * Microsoft MS-DOS 6.21 Standard Edition
 * Microsoft MS-DOS 6.22 Standard Edition

-



This article was previously published under Q61806



SUMMARY
This article describes a quick way to determine how many floppy disk drives, serial ports, and parallel ports are connected to the machine on which your software is running.



MORE INFORMATION
During the boot process, the ROM BIOS examines the computer's various connectors and sets an equipment-list word accordingly. This word is located at absolute address 410 hex or segment 0000, offset 0410 (hex). Interrupt 11 hex returns the word in the AX register. The bits of the word are defined as follows:   Bit       Description -

0        Set if any floppy disk drives present

1        Set if math coprocessor installed

2        Set if pointing device attached (PS/2)

3-2      System board RAM size (only for original IBM PC, PCjr):

00 = 16K 01 = 32K 10 = 48K 11 = 64K

5-4       Initial video mode:

00 = reserved 01 = 40-column color 10 = 80-column color 11 = 80-column monochrome

7-6       Number of floppy disk drives (if bit 0 set):

00 = 1 drive 01 = 2 drives 10 = 3 drives 11 = 4 drives

8        Reserved

11-9     Number of serial ports

12       Set if game adapter installed

13       Set if serial printer attached (PCjr) Set it internal modem installed (PC and XT only)

15-14    Number of parallel ports

Additional query words: 3.20 3.21 3.30 3.30a 4.00 4.01 5.00 5.00a 6.00 6.20 6.21 6.22

Keywords: KB61806

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.