back2root:ibm-pc-ms-dos:hardware:informations:edba

Table des matières

Pointing Device Flag Byte 1
Pointing Device Flag Byte 2
Notes

EBDA - Extended BIOS Data Area EBDA (PS/2)

Offset	Size	Description
00	word	number of bytes allocated to EBDA in Kbytes
01-21	21bytes	reserved
22	dword	device driver far call pointer
26	byte	pointing device flag (1st byte, see below)
27	byte	pointing device flag (2nd byte, see below)
28-2F	8 bytes	reserved

Pointing Device Flag Byte 1

bit	Offset 26
0-2	index count
3	reserved (0)
4	error
5	acknowledge
6	resend
7	command in progress

Pointing Device Flag Byte 2

bit	Offset 27
0-2	package size
3-6	reserved
7	device driver far call flag

Notes

EBDA is located in highest memory just under 640K on PS/2
word at BIOS Data Area 40:0E is segment address of EBDA

back2root/ibm-pc-ms-dos/hardware/informations/edba.txt · Dernière modification : 2023/01/16 18:03 de frater