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From: vishniac@wanginst.UUCP (Ephraim Vishniac)
Newsgroups: net.micro.mac
Subject: Re: HFS on MacSCSI?
Message-ID: <1525@wanginst.UUCP>
Date: Wed, 8-Jan-86 08:39:03 EST
Article-I.D.: wanginst.1525
Posted: Wed Jan  8 08:39:03 1986
Date-Received: Thu, 9-Jan-86 06:03:31 EST
References: <1717@rocksvax.UUCP>
Distribution: net
Organization: Wang Institute, Tyngsboro, Ma.  01879
Lines: 31

> Has anyone out there in net land made this work?  I am still patiently
> waiting for my developers package I ordered last month, but in the
> interim I obtained a copy of the Hard Disk 20 system disk.  I have
> looked at what block #2 has in it and tried to emulate all I saw.
> When I set it up like the old file sys, zero out the disk and write block 
> with volume info, I get the Sys Bomb 27 (your directory is mangled message).
> 
I've had no trouble (except the trouble of getting the software, but that's
another story) running HFS through the MacSCSI hardware with my own driver.
To change from flat to HFS, I simply chose "erase disk" from the finder's
"special" menu.  

Erase disk makes a #5 control call (format) followed by a #6 control call
(verify formatting).  For format, I do a real format of the disk, then
rewrite every sector with all zeroes.  For verify, I return success immediately
without doing anything.  The finder then rebuilds the volume header.

***It is very important that your drive queue entry have the correct drive
size in it.***  The last word of the drive queue entry gives the number
of sectors.  IM lists this as an INTEGER, which it was under finder 4.1 and
earlier, but finder 5.0 and later seem to read it as UNSIGNED.  That's a
good thing, because otherwise you were shafted after 16 Megs: finder 4.1
went bananas with "negative" drive sizes.

Has anyone (except Shulman @ Rutgers) received the December supplement?
I'm still waiting for my copy, and Apple's had my $25 for six weeks now...

-- 
Ephraim Vishniac
  [apollo, bbncca, cadmus, decvax, harvard, linus, masscomp]!wanginst!vishniac
  vishniac%Wang-Inst@Csnet-Relay