Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ICAEN.UIOWA.EDU!dbfunk
From: dbfunk@ICAEN.UIOWA.EDU (David B Funk)
Newsgroups: comp.sys.apollo
Subject: Re: PAD types
Message-ID: <9002200247.AA00104@icaen.uiowa.edu>
Date: 20 Feb 90 02:36:05 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: Iowa Computer Aided Engineering Network, University of Iowa
Lines: 42

In posting <1990Feb18.230542.24066@idacom.uucp> Danny Wilson writes:

>A while back I ported a UNIX program to SR9.7 and enhanced its
>output because of the way PADs handle character output.

[stuff deleted]

>So, I enhanced the program to create a little window at the top of 
>the pad to display the 'counting' numbers in.  It went something like:
>
>	inquire about stdout;
>	if it is of type pad_$uid, then
>		create a little window with frame
>		open a stream to that window/frame
>		put the output there
>	else
>		put the output to stdout
>
>However, now that we've upgraded to SR10.1, the program no longer works!
>
>The inquiry about ios_$stdout yields that it is of type "input_pad_$uid"
>instead of simply "pad_$uid".
>
>WHY?  I can't really see why the "output" should be of type "input"... etc
>Has anyone out there seen this weirdness and can explain it?

  My guess is that you've been hit with more JLRU. At sr10, the "tty" command
will return a "tty device" for any interactive shell, even a DM pad. Thus 
the "tty" for your DM window is its transcript pad, "/dev/display" and 
all those "/dev/pad*" thingies. Unix expects "/dev/tty" to be both readable
and writeable, and can't understand the idea of having std-in and std-out
going to 2 different types of "devices" for the same "/dev/tty". Thus if
you look at all your standard streams for your shell in a DM window using
the "/com/lopstr" tool, you'll see that they are all "input pad".

  One workaround for this that is OS rev independent: at sr10 they've finally
documented the DM pad call "pad_$isa". Give this little gem your std-out or other
stream, and it'll return a status of OK if its to a DM pad, error otherwise.
I can see where this'll become important when there's more X stuff around.
Then a window may not be a DM pad.

Dave Funk