P C M E M O R Y M A P (BIOS DATA AREA)

(0000:0400 - 0000:04FF or 0040:0000 - 0040:00FF) Interrupt Vectors

Communications

0000:0400 - 0401 Address of COM1:

0000:0402 - 0403 Address of COM2:

0000:0404 - 0405 Address of COM3:

0000:0406 - 0407 Address of COM4:

Printer

0000:0408 - 0409 Address of LPT1:

0000:040A - 040B Address of LPT2:

0000:040C - 040D Address of 3.printer port

0000:040E - 040F Address of 4.printer port

0000:0410 - 0411 Equipment flag

0000:0412 - 0412 Manufacturing test indicator

0000:0413 - 0414 Memory on planar

0000:0415 - 0416 Memory in I/O channel for 64K PC

Manufacturing test area for XT

Keyboard

0000:0417 - 0418 Keyboard flags

0000:0419 - 0419 Alt key numeric input

0000:041A - 041B Keyboard buffer head pointer

0000:041C - 041D Keyboard buffer tail pointer

0000:041E - 043D Keyboard buffer

Diskette

0000:043E - 043E Disk seek status

0000:043F - 043F Disk motor status

0000:0440 - 0440 Disk motor timeout

0000:0441 - 0441 Disk status

0000:0442 - 0448 Disk controller status bytes

Monitor

0000:0449 - 0449 CRT mode

0000:044A - 044B CRT columns

0000:044C - 044D CRT regen buffer length

0000:044E - 044F Starting address in regen buffer

0000:0450 - 0451 Cursor pos. for CRT page 1

0000:0452 - 0453 Cursor pos. for CRT page 2

0000:0454 - 0455 Cursor pos. for CRT page 3

0000:0456 - 0457 Cursor pos. for CRT page 4

0000:0458 - 0459 Cursor pos. for CRT page 5

0000:045A - 045B Cursor pos. for CRT page 6

0000:045C - 045D Cursor pos. for CRT page 7

0000:045E - 045F Cursor pos. for CRT page 8

0000:0460 - 0461 Cursor mode

0000:0462 - 0462 Activ page number

0000:0463 - 0464 Address of current display adapter

0000:0465 - 0465 CRT mode

0000:0466 - 0466 Palette setting

POST data

0000:0467 - 0468 Ptr to ROM initialization routine

0000:0469 - 046A Ptr to ROM segment

0000:046B - 046B Interrupt flag

Timer

0000:046C - 046D Low word of timer count

0000:046E - 046F High word of timer count

0000:0470 - 0470 Timer overflow

0000:0471 - 0471 Break indicator

0000:0472 - 0473 Reboot (Ctl-Alt-Del) indicator

0000:0474 - 0477 Fixed Disk data area

0000:0478 - 0478 Printer 1 timeout

0000:0479 - 0479 Printer 2 timeout

0000:047A - 047A Printer 3 timeout

0000:047B - 047B Printer 4 timeout

0000:047C - 047C RS232 1 timeout

0000:047D - 047D RS232 2 timeout

0000:047E - 047E RS232 3 timeout

0000:047F - 047F RS232 4 timeout

0000:0480 - 0483 Additional keyboard buffer pointers

0000:0490 - 04CF Used by MODE.COM

0000:04D0 - 04EF Reserved

0000:04F0 - 04FF Intraapplication communication area