Re: UMAX 1200S Astra hangs, then resumes

Greg Troxel (gdt@fnord.ir.bbn.com)
14 Dec 1998 08:57:12 -0500

I have a 486-100 with an ASUS SP3G motherboard with a built-in 53c810
and a UMAX 1200S. I had hangs which might have been similar, but I
was never that patient. I guessed that the problem might have been a
page fault occuring in xscanimage while trying to write data from the
scanner; this would then need to use the SCSI bus to page things back
in. I never confirmed this speculation, but I avoided having other
large programs running (I only had 32 Mb of RAM) and this didn't recur
often. I have since upgraded the machine to 96 Mb RAM, and haven't
had the problem since.

The UMAX is said not to support disconnect/reconnect, and thus to hang
the scsi bus for the scan duration. I believe this is true, except
that a scan is typically composed of a number of smaller transfers,
each of which is uninterruptible.

All that said, one could believe that you had a page fault, which
caused the scanner transfer to time out. Then, the page fault could
be serviced, and things would continue. I almost got around to having
scanimage touch all the memory that would be used by a SCSI read
before doing the read, but I haven't lost enough to get motivated.

Greg Troxel <gdt@ir.bbn.com>

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