Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!wuarchive!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpfcso!hpfinote!pnl
From: pnl@hpfinote.HP.COM (Peter Lim)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Harddrive led won't stop
Message-ID: <19450043@hpfinote.HP.COM>
Date: 1 May 90 19:51:07 GMT
References: <10090@sdcc6.ucsd.edu>
Organization: Hewlett Packard CICD
Lines: 30

> 
> This is quite normal for most AT hard disks.  The controller is in 'latched'
> mode and keeps the last physical drive selected until another physical 
> drive is
> selected.  If you only have one hard disk then the drive will remain selected
> until you turn off the computer.  I use a WD controller and it has 
> a jumper to
> enable/disable the latched mode.  I have no idea why they have this latched
> mode.  The only possibility would be speed but surely it doesn't take 
> that long just to select the drive.
> 

I use a DTC 6280 and it also has a jumper to enable/disable the latched mode.
I tried to disable the latched mode once and the disk runs a LOT SLOWER.
Very noticeable difference.  It probably do more than just select the drive;
probably keep the drive in a ready state (may be high speed spinning ??
-- can hard disk be slowed down and placed in a sleep mode by the
controller ? -- sounds reasonable if they are to be usable in a
portable computer).

Anyway, it is normal.


Regards,                       ## Life is fast enough as it is ........
Peter Lim.                     ## .... DON'T PUSH IT !!          >>>-------,
                               ########################################### :
E-mail:  plim@hpsgwg.HP.COM     Snail-mail:  Hewlett Packard Singapore,    :
Tel:     (065)-279-2289                      (ICDS, ICS)                   |
Telnet:        520-2289                      1150 Depot Road,           __\@/__
  ... also at: pnl@hpfipnl.HP.COM            Singapore   0410.           SPLAT !