INT 12h (18)             Report Memory Size

Reports the number of contiguous 1K memory blocks in the system (up to
640K).

On entry:      No parameters

Returns:       AX         Memory size (up to 640K)

                                                                          

Notes:         This service determines memory by either examining
the DIP switches on the system board or using the
value stored in the CMOS battery, depending on the
type of machine.

The value returned in AX is the same as that stored
at memory location 0:0413h, which is initialized
during the power-up tests.

This is the amount of memory available to the entire
system. This is not the amount of memory available
to the user's program. Use INT 21h, Function 48h, to
determine the amount of memory available to a user's
program.

To determine the amount of memory above the 1024K
address range, use INT 15h, Service 88h.

If the CMOS battery memory value or the DIP switch
value is greater than the actual amount of memory,
then the actual amount of memory is returned by this
interrupt.

See also: 48h
See also: INT 15h, 88h

INT 12h (18) Report Memory Size