Newsgroups: sci.image.processing
From: paul@pcserv.demon.co.uk (Paul Carpenter)
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!usenet.eel.ufl.edu!eng.ufl.edu!spool.mu.edu!howland.reston.ans.net!pipex!demon!pcserv.demon.co.uk!paul
Subject: Re: high speed digital i/o board
References: <compusco.5.000DD7B5@silcom.com>
Organization: PC Services
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Date: Sat, 22 Oct 1994 08:56:30 +0000
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In article <compusco.5.000DD7B5@silcom.com> compusco@silcom.com  writes:
-Does anybody know a manufacturer of high speed digital i/o boards (>=1MB/s)?  
-24 bit wide parallel.  Simple communications, data is latched 12-16 bits. The 
-board should plug into a IBM PC/ compatible without a fuss.  Data needs to be 
-dumped to video and CPU RAM for image analysis.

From this brief requirement I can only assume that the following:-

1	Digital I/O is TTL levels? (not RS422/ECL...)
2	Data run is probably 1-4Mb? As you are talking of video images.
3	ISA bus card (as data is latched 12-16 bits) ?

As 'standard' ISA bus traffic is about 1MHz flat out, direct plug in to the PC
*may* well be reaching or exceeding the limits of the ISA bus. I am currently 
unaware of any EISA/PCI/VESA bus Digital I/O cards for any sort of speed work.

The most common ways I have come across is for people to use cards with specific
digital inputs and on board memory, in order to save a copy of the data at the 
rate the data is coming in. Some typical types of cards:-

	Frame Grabbers (only seen 8bit wide transfers personally)

	DSP cards with Digital I/O interfaces (eg Alacron DSP with DI I/F)

Note the Alacron DI interface can cope with 8 to 64bit I/P data width as TTL or 
RS422 or RS423 level signals clocked at upto 30MHz (240Mb/s). By using some of
the DSP memory cards it is possible to put some large amounts of memory on board
for sequences of images that could not be captured into Host RAM.

Also some imaging applications like Foster Findlay's C-Images work on the DSP
direct.

Just a few suggestions that is a _non-exahustive_ list.

-- 
Paul - "Any people you should meet are the products of a deranged imagination"
