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From: zambotti@wpowz.enet.dec.com (Walter Zambotti DEC)
Newsgroups: comp.os.os9
Subject: Re: open() + sharable file = no disk
Message-ID: <1991Jun14.013807.9413@tkou02.enet.dec.com>
Date: 14 Jun 91 01:38:07 GMT
References: <1991Jun11.012640.904@tkou02.enet.dec.com> <1656@seq.uncwil.edu> <1991Jun12.012958.10534@tkou02.enet.dec.com> <1991Jun13.164946.25872@watdragon.waterloo.edu>
Sender: usenet@tkou02.enet.dec.com (USENET News System)
Reply-To: zambotti@wpowz.enet.dec.com (Walter Zambotti DEC)
Organization: Digital Equipment Corporation
Lines: 46

Hi there again guys,

Looks like the Tandy Developement Pack RAM disk driver is buggy.

>Not well-known fact: OS-9 also checks the device descriptor M$Mode setting.
>So my immediate thought was that this capability mode byte in the /R0
>device descriptor wasn't fully turned on.  And yep, it wasn't.

>Check the byte at offset $0D in your /R0 descriptor.  It is $BF now...
>which means the shareable attribute is turned off.  Change it to $FF,
>reverify, reboot, and I think all should be fine.

Well I tried this and it doesn't work.  It seems that the ram driver
incorrectly copies this byte into the file permissions byte of the /r0
directory file header.  So that when you do this :

	dir /r0
	error 253    (non-sharable file busy)

this is definitely incorrect.  The /r0 (or root) directory of every disk
has its own file header with its own file permissions attribute byte. 
It is incorrect for the initialization routine of the ram driver to copy
the disk attribute byte into file attribute byte of the file header of
the /r0 directory.

Even though the above error is received when a dir is performed upon /r0
it is still possible to create delete and every else on this now
non-sharable disk???   This must be a bug!  You can either use it or not
use it.  Non-sharable shouldn't just effect the dir command it should
effect any type of access.

Anyway my tstmod program still fails with error 203 (cannot perform
specified function) when run with mode 64+?.  And after running tstmod
any use on the /r0 device returns the error 241 (sector number out of
range).

It looks like its time to disassemble the ram driver.  I'll have a crack
at this but don't hold your breath waiting as I dont have much
experience in this sort of thing.

I'll continue to write the ln(1) command but it's not going to work on
the Tandy ram disk for a while.

regards,

Walter