Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!mcvax!ukc!reading!cf-cm!cybaswan!iiit-sh
From: iiit-sh@cybaswan.UUCP (Steve Hosgood)
Newsgroups: comp.os.os9
Subject: Re: SCF Device Driver Query (68K)
Summary: It's the Echo Device field
Keywords: SCF
Message-ID: <468@cybaswan.UUCP>
Date: 25 May 89 14:37:04 GMT
References: <455@cybaswan.UUCP>
Reply-To: iiit-sh@cybaswan.UUCP (Steve Hosgood)
Organization: Institute for Industrial Information Technology
Lines: 31

In article <455@cybaswan.UUCP> iiit-sh@cybaswan.UUCP (that me!) writes:
>I wonder if any readers here are familiar with this problem..
>...in that the WRITE routine never gets called by the SBF file manager.
>

OK, I found the answer. I'd not set the PD_D2P field in the descriptor to
refer to the driver. This is the 'Echo Device Name' field.

I consider this to be indicative of a broken SCF manager, what do you think?
For instance, I can understand that if the manager itself was trying to write
characters that are echoes for input characters then it uses the input device's
'echo device' to write them. However, in my case I was WRITING them to the
device from a program. This is not really the same thing as ECHOING them, so
SCF shouldn't use the 'echo device' field.

Even so, when it found it couldn't write my characters, it returned status
indicating OK to me, the user. This too is broken isn't it? If it didn't
write then the 'write' call should return -1, and errno should tell me why.

Mutter mutter mutter......

This has cost me 2 weeks :-(

-----------------------------------------------+------------------------------
Steve Hosgood BSc,                             | Phone (+44) 792 295213
Image Processing and Systems Engineer,         | Fax (+44) 792 295532
Institute for Industrial Information Techology,| Telex 48149
Innovation Centre, University of Wales, +------+ JANET: iiit-sh@uk.ac.swan.pyr
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