Format of COMBI-disk command packet:
Offset	Size	Description	)
 00h	WORD	version
 02h	BYTE	command code (see #01538)
---command code 80h---
 no additional fields
---command code 81h---
 03h	BYTE	new options byte (see #01540)
---command code 82h---
 03h	WORD	number of KB to release
---command code 83h---
 03h	WORD	number of KB to expand
---command code 84h---
 03h	DWORD	-> buffer for block info (see #01541)
---command code 85h---
 03h	DWORD	block ID
---command code 86h---
 03h	BYTE	which counters to reset
		bit 0: hard disk read counts
		bit 1: hard disk write counts
		bit 2: RAM disk read/write counts
Note:	multiple commands may be placed in a single packet by stringing
	  together as many command/argument pairs as desired