http://groups.google.com/groups?q=hd20+group:net.micro.mac&hl=en&lr=&ie=UTF-8&group=net.micro.mac&selm=374%40decwrl.DEC.COM&rnum=1

A tip on reformatting the HD20: in January MacTutor one fellow describes how
he got his done after it was 'blasted into bit-heaven' by MacZap.  Apparently
there is an unknown option in the HD20 Test program that appears if you hit
Cmd-D at the dialog box.  (Something about a destructive test)  Using that
and turning the HD20 on and off several times (sounds dangerous to me) he got
the drive 'damaged enough' for the boot disk to initialize it.  The logical
way seems to boot the HD20 startup disk with the mouse down and when the HD20
appears as the second drive, select it and choose initialize.  Has anyone
tried that?  I'm wary of doing it until a decent backup program is in my
hands.  Does anyone know of one, or one to come out soon?  It sure is
necessary...especially since my System is 471K!

Happy Maccing!


Chris Borton, UC San Diego Undergraduate CS 
Micro Consultant, UCSD

--------------------------------------------------------------------------------

Message 2 in thread
 From: Darin Adler (darin@ut-dillo.UUCP)
Subject: Re: HD20 error handling at boot 


Ê

View this article only
 Newsgroups: net.micro.mac
Date: 1986-01-27 21:37:27 PST 
<

> Can anyone explain what the HD20 does upon boot after a crash?  Depending
> upon the situation before "the bomb" it will take 2-3 times longer before it
> ejects the floppy.  During that time some intensive hard disk stuff is going
> on.  Everything always turns up fine, but I'm curious what it's doing.  It's
> particularly bad recovering from Switcher with 2-3 applications.  (Gee, I
> wonder why? :-) )

As explained to me at the developer's conference by Scott Knaster:

 The HFS file system maintains a bit map that determines which
 sectors on a disk are free and which are used.  (This in addition to
 a "extents file" that determines where each file is stored.)  When a
 system crash occurs, some sectors may be marked as used, even though
 they are unused, and vice-versa.  When a volume is mounted, if it
 was not properly Unmounted/Flushed the last time it was used, a
 "scavenge" routine runs, determining which sectors are used/unused.

This was nice to hear, because before using HFS, my Corvus volumes would
gradually lose sectors until I had to re-format them.
-- 
Darin Adler {gatech,harvard,ihnp4,seismo}!ut-sally!ut-dillo!darin

"Such a mass of motion -- do not know where it goes" P. Gabriel

--------------------------------------------------------------------------------

Message 2 in thread 
From: Chris Borton (borton@sdcc3.UUCP )
Subject: Re: HD-20 Test question 

Ê

View this article only 
Newsgroups: net.micro.mac 
Date: 1986-01-18 12:06:56 PST 
In article <536@decwrl.DEC.COM> harrow@exodus.DEC (Jeff Harrow, NCSE LKG1-3/F16 DTN=226-7445) writes: >After reading the comment someone made that you could get more options/info 
>from the HD20  Test  program  supplied on the HD20 Startup disk, I tried it 
>out by hitting COMMAND-D at it's initial dialog box.
>
>Sure enough, it gave  me  some  windows that looked interesting, but when I 
>hit START, the system BOMBed, and did this every time I tried.
>
>Has anyone else tried this and been successful?
>
>Jeff I tried it and it worked fine.  For those curious, if you hit Cmd-D at the
initial dialog box on the HD20 test it then shows two windows: one has boxes
containing Block Count, Iteration, Soft Rate, Hard Rate, Comm Rate, Loops,
Total Blocks, and Failure Code.  There is also a radio button labelled Dstrct
which, I believe, will allow you to reformat the hard disk.  The program also
creates a document file that has a log of the tests done and the results.

I'm not sure if it matters in this case, but I'm using System 3.0/Finder 5.1.
One curious thing I found is that to redo the DeskTop file I can't have the
hard disk as the boot volume, for when it is done redoing the DeskTop it goes
out to lunch and never comes back.  Booting the HD20 Startup disk with mouse
down and Cmd-Opt after the floppy is mounted will redo the hard disk correctly.
Incidentally, this is a good thing to do every 2 weeks since my last time I
retrieved 77K!

As for parking the heads being necessary, can someone at Apple or in the know
comment?  I would feel much happier if I KNEW safeties were provided for.
The glaring lack of any backup facility for the HD20 doesn't make me feel
that 'Apple knows best' in this case at all.

A salesman at a local computer store told me yesterday when questioned about
SCSI 'upgrades' for the HD20 that it was already built in, and could simply
be plugged in as is.  This is very well done, if it is correct.

Happy Maccing!

--Chris
---------

Chris Borton, UC San Diego Undergraduate CS 
Micro Consultant, UCSD

--------------------------------------------------------------------------------
From: authorplaceholder@inmet.UUCP (authorplaceholder@inmet.UUCP)
Subject: Re: Lightspeed C & Hard Disk 20 


Ê

View this article only
 Newsgroups: net.micro.mac
Date: 1986-07-12 13:39:00 PST 

It is true that there are at least two versions of the HD20 driver
file.  This file is used by those of us who kick start our HD20's.  The
one dated in Sept of 85 is bogus.  The one dated in early 86 is fine.
They are exactly the same size.  The HD20 file used is the one on your
kick start disk, not the one on your HD20.

  In LightspeedC the bogus HD20 driver will manifest its short comings
by refusing to let you add projects or libraries from the Lightspeed
system folder.
  - ben hyde, cambridge.

--------------------------------------------------------------------------------

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&threadm=486%40well.UUCP&rnum=47&prev=/groups%3Fq%3Dhd20%2Bgroup:net.micro.mac%2Bgroup:net.micro.mac%2Bgroup:net.micro.mac%2Bgroup:net.micro.mac%26hl%3Den%26lr%3D%26ie%3DUTF-8%26group%3Dnet.micro.mac%26start%3D40%26sa%3DN

From: Frederick A. Huxham (bmug@well.UUCP)
Subject: Only 391K in disk? 


Ê

View this article only
 Newsgroups: net.micro.mac
Date: 1986-01-14 00:44:26 PST 
Someone recently posted something about formatting floppys with
Finder 5.* and coming up with only 391K in disk?  They were somewhat
upset.  

No need to worry, the reason you (seem to) lose 9K on every disk
is that Apple used to count 1K as 1000 bytes.  Unfortunately, 1K =
1024 bytes.  They figured it out by the time they got to Finder
5.* so now when it adds up how much space you have on disk it 
comes up with a slightly smaller number.

Also, for the people that have copied black holes into their
HD20's, there are 2 programs floating around called
HD Diag, and Scavenger Mac which are HD utilities.  The programs
seem to allow you to format individual tracks, zero and initialize the
disk, recover lost files and a zillion other things.  I don't have 
an HD20 so I can only boot them up and read the menus, I'm not
absolutely sure what the applications do, but they seem like they
might be what you want.  

They're Apple's programs so I'm not in a position to post them, but
if Apple would like to...

Fred A. Huxham

--------------------------------------------------------------------------------

http://www.mactech.com/articles/mactech/Vol.02/02.01/Jan86Mousehole/


Hacking into the HD-20
  

JIM REEKES
 

Just got a few new "hacking" tools for the HD20.  FEdit 3.21 (can view the HD20);  F/DA Mover 2.5  Backup DA (a DA that will backup the HD20?);  HD Diag (diagnostic program used in dev. by Nisha and Rodime, this puppie can read/write any bit on the HD20.  A note about the HD Diag says "Do not use Init Mac Dir or the Init Spare Table unless you've had a personal discussion with R. Mohme). Also, what's the story behind RENE'?  That's the name of the device driver  for the HD20.  I heard something about this girl who liked to party with  software engineers.  Can anyone fill us in on this?

Scavenger Mac is on one of the floppies at:

http://www.applefritter.com/software/bcs/