

ISSUES


1) CYLINDER/HEAD/SECTOR  to/from BLOCK
    NUMBER conversion algorithm.

	- MUST be consistant for ALL Operating Systems
	   that run on a particular platform.

2) STRUCTURE-based Interface.

	- Allow multi-threaded access.
	- Allow (require) disconnect.
	- Minimal structure size.

3) Automatic REQUEST SENSE on Check Condition.

4) SCSI Access Library.

5) TARGET Mode.


ISSUES

CYLINDER/HEAD/SECTOR  to/from BLOCK NUMBER conversion algorithm.

OPTIONS:

	1) Use actual geometry parameters from MODE
	     SENSE.

		pros: - maintains status quo.
			   - allows O/S disk access "tuning".

		cons: - cylinder value too large for 10 bits on
				larger disks (as small as 100MB).

	2) Use maximum head (256) and sectors/track
	    (64) values. (using up to 8 bits for head #)

		pros: - easy to implement.
			   - allows larger disks.
			   - maintains structure compatibility.

		cons: - can waste disk space on partial cyl.
				(up to 8MB per "cylinder")
			   - lose O/S disk access "tuning".


ISSUES


	#bits for head	KB/"cylinder"         MB/"disk"
		    4			      504                          504
		    5			    1008                        1008
		    6			    2016                        2016
		    7		           4032                        4032
		    8                   8064                        8064

	3) Define an algorithm that selects optimum values
		for number of heads, sec./trk, and cylinders.

		pros: - less waste on last partial cylinder.
			   - allows larger disks.
			   - maintains structure compatibility.
			   - may allow disk access "tuning".

		cons: - harder to define.
			   - harder to implement.
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