INT 11 - BIOS Equipment Determination / BIOS Equipment Flags
no input data on return: AX contains the following bit flags: │F│E│D│C│B│A│9│8│7│6│5│4│3│2│1│0│ AX │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └──── IPL diskette installed │ │ │ │ │ │ │ │ │ │ │ │ │ │ └───── math coprocessor │ │ │ │ │ │ │ │ │ │ │ │ └─┴────── old PC system board RAM < 256K │ │ │ │ │ │ │ │ │ │ │ │ │ └───── pointing device installed (PS/2) │ │ │ │ │ │ │ │ │ │ │ │ └────── not used on PS/2 │ │ │ │ │ │ │ │ │ │ └─┴─────── initial video mode │ │ │ │ │ │ │ │ └─┴────────── # of diskette drives, less 1 │ │ │ │ │ │ │ └───────────── 0 if DMA installed │ │ │ │ └─┴─┴────────────── number of serial ports │ │ │ └─────────────────── game adapter installed │ │ └──────────────────── unused, internal modem (PS/2) └─┴───────────────────── number of printer ports - bits 3 & 2, system board RAM if less than 256K motherboard 00 - 16K 01 - 32K 10 - 16K 11 - 64K (normal) - bits 5 & 4, initial video mode 00 - unused 01 - 40x25 color 10 - 80x25 color 11 - 80x25 monochrome - bits 7 & 6, number of disk drives attached, when bit 0=1 00 - 1 drive 01 - 2 drives 10 - 3 drive 11 - 4 drives - returns data stored at BIOS Data Area location 40:10 - some flags are not guaranteed to be correct on all machines - bit 13 is used on the PCjr to indicate serial printer