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

	|7|6|5|4|3|2|1|0| Offset 26
	 | | | | | `------- index count
	 | | | | `-------- reserved (0)
	 | | | `--------- error
	 | | `---------- acknowledge
	 | `----------- resend
	 `------------ command in progress

Pointing Device Flag Byte 2

	|7|6|5|4|3|2|1|0| Offset 27
	 | | | | | `------- package size
	 | `-------------- reserved
	 `--------------- device driver far call flag

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

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

Pointing Device Flag Byte 1

Pointing Device Flag Byte 2

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