campbell@perth.honeywell.com.au
Wed, 1 Jul 1998 08:30:48 +0800
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> Just bought a new scanner today... boy have the prices come down. Anyway,
> if this isn't already an emerging topic for this list, it should be! Every
> single one of the scanners in my price range (< $200) is now parallel-port
> driven. So of course I shrugged and thought, "well, there goes all
> possibility for Linux support."
*sigh* And I thought I was going to avoid this topic.
Yes, the prices for parallel port scanners have fallen to rock bottom
prices. A quick tour of Sim Lim Square (a shopping tower with seven floors
of electronics/computers in Singapore - I visit it everytime I come here
[currently doing a two week stint in Singapore]) reveals at least 10 different
brands with each brand having several different models.
Without being involved in the SANE (Scan Anywhere Now Easy) project I do not
know how complicated the protocol will be. (See URL later)
Some scanners may actually be a SCSI beasts internally with a parallel to SCSI
interface. These typically load device drives before windows starts (Win 3.1).
Others use a proprietry protocol.
Normally for parallel port devices it is possible to load the MS-DOS driver
under DOSEmu and pick apart the protocol. The SCSI protocol is very obvious to
spot providing you understand the SCSI sequence. Presumably IDE protocol is the
same. The problem with scanners is that no-one has a DOS based scanning
program, they all use at least Win 3.1
As far as I know (correct me if I am wrong), nobody has managed to fire up
Win 3.1 under DOSEmu and load a scanner. Also I do not know of any report of
WINE (I haven't heard much about WINE lately) supporting scanners. Until this
has been accomplished it will be next to impossible to obtain a port trace of a
scanner (unless someone has a 16 channel 10 MHz bandwith digital storage
oscilscope).
A comment about 9-12 months back suggested writing a virtual device driver
(VXD) for Win95 which would create a phantom parallel port for tracing
purposes. Nothing has come of this.
If someone actually finds a way to obtain a port trace under windows, this
would be a BIG help in several areas other than parallel port scanners
I have a page which describes the "current state of play" for parallel port
scanners. I do not claim this to be authorative or complete and welcome any
additions/suggestions. The page has a link to the SANE project (for those
wanting more info).
http://www.torque.net/~campbell/scanner.html
David Campbell
PS: Another 12 hour day dealing with VMS again, it is enough to drive a
programmer to kernel hacking.
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