Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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  Address
  (hex)       Size      Description
 
  0000:0400   4 words   Base addresses of serial ports COM1 to COM4.
 
  0000:0408   4 words   Base addresses of printer ports LPT1 to LPT4.
 
  0000:0410   1 word    List of system equipment in the following
                        format:
 
                        Bit     Meaning (if set)
 
                        0       Disk drive installed
                        1       Coprocessor installed
                        2-3     PC: Amount of system board RAM
                                    00 = 16 KB
                                    01 = 32 KB
                                    10 = 48 KB
                                    11 = 64 KB
                                AT: Not used
                                PS/2:01 = Pointing device installed
                        4-5     Initial video mode:
                                11 = Monochrome text
                                10 = 80-column text
                                01 = 40-column text
                        6-7     Number of disk drives, if bit 0 set
                        8       Not used
                        9-11    Number of serial ports installed
                        12      Game adapter installed
                        13      Not used
                        14-15   Number of printers installed
 
  0000:0413   1 word    Amount of conventional memory in kilobytes.
 
  See also: Interrupt 11h (Get Equipment Configuration),
            Interrupt 12h (Get Conventional Memory Size)
                                    -♦-