Re: send more than 8 bits with parallel port

On Wed, 22 Feb 2006 16:20:58 GMT, "Michael A. Terrell"
<mike.terrell@xxxxxxxxxxxxx> wrote:

Jonathan Kirwan wrote:

On Tue, 21 Feb 2006 14:15:56 GMT, NoSpam@xxxxxxxxxxx (Bob Masta)
wrote:

<snip>

Others have answered the hardware aspect of your
question. However, note that if you plan to use this
on PCs running Windows versions later than 9x,
you will have to use a special ring 0 device driver to have
access to the printer port. (GIVEIO and USERPORT are
two that I have heard of, put haven't tried myself.)
That might be one advantage for using the serial
port, which can be accessed through more-or-less
standard Windows API functions.

Another thing to think about is that parallel printer ports
are rumored to be slated for extinction... but then again,
aren't we all!

You know? What bugs me about this very true point is that we are
losing all of the really good hobbyist interfaces for adapting a PC.
The ISA bus was really nice and not too complex for a serious hobbyist
to use, in adding boards. Gone now, or nearly so. Ever consider
trying to do a PCI card as a hobbyist? Reflection wave bus, 2ns clock
skew on 33MHz and 1ns clock skew on 66MHz with a 1.5" +/- 0.1" trace
length for the clock (often serpentined in order to get there), etc.
Just getting equipment to monitor the analog characteristics for
debugging a design is a fortune. Lose the parallel, lose the serial,
add USB 2.0, replace the old IDE controller cables with SATA 2, and
what are you left with to use, anymore? It's getting to be a pain in
the ...

Well, of course, there are microcontroller boards. But then you lose
out on the excellent and easy availability of very excellent and well
documented development tools.

Jon

PC-104 is just a reconfigured ISA bus and the cards stack rather than
plug into a motherboard. The last ones I worked with had a Cyrix 586
CPU, and were running embedded NT in the Microdyne/L3-com RCB2000
telemetry receiving system. I still have some of the data on the board
around here, somewhere.

Yes. But I think the PC-104 is dying. As I understand it, from
talking with a few key manufacturers in that business, the ability to
secure PC-compatible CPUs _with_ the ability to provide PC-104
signaling isn't likely to survive many more years. They are meeting
(or were) to try and see if they could collectively (some of the
bigger ones, anyway) pony up for their own ASIC design to handle the
PC-104 bus, before the remaining suppliers stop making their parts.
But I fear this whole attempt will fail and they will be forced to use
PC-104+ only (PCI.)

I'm not privy to the whole picture, but here is about how I see it.

There were some CPU manufacturers who provided x86 CPUs with ISA
interfaces. But there are several pressures away from what remains of
these, if anything does. For one, customers are usually looking for
faster and faster CPUs, even in the PC-104 business. And faster CPUs
probably use the front side bus arrangement for the CPU, followed by a
chip that mediates between that and the PCI, followed by another chip
that mediates between the PCI and the ISA and has all kinds of
sideband channels back to the chip that handles the front side to PCI,
since ISA DMA transactions cannot be properly remapped as PCI
transactions and require "special support." No one wants to keep
making the PCI to ISA bridge for that mess -- except maybe the PC-104
folks. But they don't have the business level to keep those current
makers making those chips. And I don't think they have the steam
themselves to get into that business.

So it will go away, soon. I think.

Jon
.

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