Extended BIOS Data Area

 Format of Extended BIOS Data Area (see 40:0Eh for ptr) [PS only]
 Offset  Size    Description
  00h    BYTE    Length of EBDA in kilobytes
  01h 15 BYTES   reserved
  17h    BYTE    Number of entries in POST error log (0-5)
  18h  5 WORDS   POST error log (each word is a POST error number)
  19h-21h        reserved
  22h    DWORD   Pointing Device Driver entry point
  26h    BYTE    Pointing Device Flags 1
                    bit 7:    =1 command in progress
                    bit 6:    =1 resend
                    bit 5:    =1 acknowledge
                    bit 4:    =1 error
                    bit 3:    =0 reserved
                    bits 2-0: index count
  27h    BYTE    Pointing Device Flags 2
                    bit 7:    =1 device driver far call flag
                    bits 6-3: reserved
                    bits 2-0: package size
  28h  7 BYTES   Pointing Device Auxiliary Device Data
  2Fh    BYTE    reserved
  30h    DWORD   Vector for INT 07h stored here during 80387 interrupt
  34h    DWORD   Vector for INT 01h stored here during INT 07h emulation
  38h    BYTE    Scratchpad for 80287/80387 interrupt code
  39h    WORD    Timer3: Watchdog timer initial count
  3Bh    BYTE    ??? seen non-zero on Model 30
  3Ch    BYTE    ???
  3Dh 16 BYTES   Fixed Disk parameter table for drive 0 (oh really?)
  4Dh 16 BYTES   Fixed Disk parameter table for drive 1 (oh really?)
                     Neither of above seen on any Model 30, 50, 60 yet.
  5Dh-6Bh        ???
  6Ch    BYTE    Fixed disk: (=FFh on ESDI systems)
                     bits 7-4: Channel number 00-0Fh
                     bits 3-0: DMA arbitration level 00-0Eh
  6Dh and up:    ??? seen non-zero on Model 60
 3F0h    BYTE    Fixed disk buffer (???!!!)