Path: utzoo!censor!geac!becker!bdb
From: bdb@becker.UUCP (Bruce Becker)
Newsgroups: unix-pc.general
Subject: Re: Optical disk for a unix-pc, is it possible?
Message-ID: <1226@becker.UUCP>
Date: 30 Nov 89 14:07:34 GMT
References: <614@mbph.UUCP> <1037@icus.islp.ny.us>
Reply-To: bdb@becker.UUCP (Bruce Becker)
Distribution: unix-pc
Organization: G. T. S., Toronto, Ontario
Lines: 40

In article <1037@icus.islp.ny.us> lenny@icus.islp.ny.us (Lenny Tropiano) writes:
|[...]
|The CD optical disk would have to be ST-506/MFM compatible.  If it's not, 
|then you can pretty much forget it.  When and *if* the 3B1 ever sees a
|SCSI interface, those opportunities will open right up.  Most likely
|the CD technology quoted here was for the 3B2 SCSI products.   I'd pretty
|much impossible to get 650MB using MFM recording.

	It's not impossible, but noone does it - RLL &
	similar encodings are generally used for large
	capacity magnetic drives.

	The 3B1 problem is addressability - 8 heads,
	1024 cylinders, 16 sectors/track, 1 drive. At
	512 bytes/sector, the total is 67,108,864 bytes.

	If a WD2010 controller is used, then one can
	use up to 2048 cylinders, for 134,217,728
	bytes, though I've never seen a ST506/MFM
	drive with that many cylinders.

	If the P5.1 upgrade is done, then 16 heads
	are addressable, for 268,435,456 bytes.
	With this upgrade it is also possible to
	have 2 drives, but the total maximum possible
	is still less that 650MB.

	The most that seems available are drives
	like the Maxtor 2190, with 1224 cylinders
	& 15 heads, giving 150,405,120 bytes/drive.

	SCSI, SCSI, SCSI, if I say it enough times
	will it magically appear? 8^)

Cheers,
-- 
   ^^ 	 Bruce Becker	Toronto, Ont.
w \**/	 Internet: bdb@becker.UUCP, bruce@gpu.utcs.toronto.edu
 `/v/-e	 BitNet:   BECKER@HUMBER.BITNET
_/  >_	 Ceci n'est pas une |    - Rene Macwrite


Brought to you by Super Global Mega Corp .com