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