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From: AWCTTYPA@UIAMVS.BITNET ("David A. Lyons")
Newsgroups: comp.sys.apple
Subject: expanded ProDOS volume dirs; Finder trick
Message-ID: <8901202038.aa01625@SMOKE.BRL.MIL>
Date: 21 Jan 89 19:12:09 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 59
X-Unparsable-Date: Friday 20 Jan 89 7:39 PM CT

>Date:         Wed, 18 Jan 89 12:43:00 CDT
>From:         MSER001%ECNCDC.BITNET@CUNYVM.CUNY.EDU
>Subject:      finder..osgs
>
>along, the line of flashing bell, press option about osgs on desktop..
>no wonder the thing is so slow...lots of hidden overhead!

The little piece of code that flips the screen upside-down if you hold
down Option while choosing About the Finder... can't be all that large;
I would be surprised if it added more than 1 or 2 blocks to the Finder's
size (the file *:system:start unless you rename it), and it certainly
doesn't slow down the system during operations other than looking at
the About the Finder... box.

>Date:         Fri, 20 Jan 89 11:05:10 MST
>From:         demarco%cpsc.UCalgary.CA%Ucnet.UNCA.AdhocNet.CA@UNCAEDU
>Subject:      Re:  GS-BBS

>[...]
>Or if you have Davex create a sys alias in the root directory that
>will run ACOS in the directory that it is  located in.

My favorite method for that sort of thing!  :-)

>Also in prodos you are limited to a max of 51 files in the root or
>top directory there is a program avalible on GEnie to change this to
>more files though.

There are at least two utilities that will expand your ProDOS volume
directory beyond the standard 4 blocks, _but_ there is a catch, and
I have never seen this discussed in the documentation for those
utilities.  (I pointed it out to one of the authors and have not
received a reply.)

The catch is that when ProDOS 8 opens a volume directory for
reading, the end-of-file is always considered to be the standard
2048 bytes ($800 bytes; 4 blocks), regardless of the number of
blocks actually in the directory.  Although files stored beyond
the first 4 blocks are accessible by pathname, they never show
up in CATALOG listings in any programs that OPEN and READ the
directory in the correct way, since they hit the end of the
file even if there's more data in there.

Only _nonstandard_ utilities that read directories by doing
direct READ_BLOCK calls will see the extra files under ProDOS 8;
such utilities are _not_ compatible with networked file servers
like AppleShare over the AppleTalk network.

Interestingly, GS/OS (more specifically, the ProDOS File System
Translator) _does_ see the extra files in an expanded volume
directory.  (It reads the whole directory when it is opened and
apparently counts up the blocks at that time.)

>Vince

--David A. Lyons              bitnet: awcttypa@uiamvs
  DAL Systems                 CompuServe:  72177,3233
  P.O. Box 287                GEnie mail:    D.LYONS2
  North Liberty, IA 52317     AppleLinkPE: Dave Lyons