davidwhess@gmail.com said:

You can do the same trick without special hardware.  Use the printer port.
Of course, that assumes your PC/Laptop still has a printer port.

I have a laptop with a printer port on the thing Dell calls a MediaBase.
It's an extender/fattener that includes a CD drive with connectors for
printer port and serial port.  It plugs into a big connector on the bottom of
the laptop.

Many laptops plug into docking stations for use at a desk.  Sometimes/often
they have printer ports and/or serial ports.

You could probably do it with just a serial port by flapping one of the
output modem control signals.

If you don't have a printer port or serial port, how are you getting the
interrupt into your box?

Many years ago, I helped a friend with this sort of thing.  We were working
for DEC back in the days before Intel had captured everything and
workstations still needed lots of chips and chips had big pins so you could
get a scope probe on them.  My part was to connect scope probes to the
interrupt line from the ethernet chip and the chip select for the MAC address
ROM.  He patched the driver's interrupt routine to read the ROM.

--
These are my opinions.  I hate spam.

On Sat, 01 Dec 2012 19:10:54 -0800, Hal Murray
hmurray@megapathdsl.net wrote:

I almost always end up installing a PCI/PCIe serial and parallel
expansion card into my systems even now.

I could not always depend on having access to built in serial or
parallel ports.  These days of course both are pretty much deprecated
in favor of USB which is useless for this type of work.

Since this was back in the ISA days, I had access to the whole ISA bus
including the interrupts.  I never built a version for PCI but I did
consider it.

The card I built had a pair of 8254 timers, hexadecimal display,
keypad, a bunch of auxiliary I/O, and all of the decoding to use it. I
usually end up building something similar for microcontroller projects
that operates via SPI although serial to a PC running a terminal
program is often better.

I have also done that on occasion and sometimes still do.  Usually I
solder a little grab point for the probe into place.  Sometimes I will
just add a resistor or transistor buffer depending on impedance issues
and an RG-316 pigtail.

The funny part is that back then, I was using one of the early
Tektronix series TDS oscilloscopes.  Now I do the same thing with an
older Tektronix 2230, 2232, or 2440 series oscilloscope and I have a
word recognizer for my 2440 which works surprisingly well.  At some
point, I need to pick up a DSO that supports variable and infinite
persistence.

Hi

Maybe I'm just shopping in the right places. I have yet to build up a desktop machine that does not have at least one COM port on the motherboard. That's been true all the way from simple little Atom based ITX boards right through monster boards with all sorts of crazy stuff on them.  Yes, it's not out the back, but that's very easy to take care of if you need the port.

Laptops are a bit different. They seem to die of some sort of display issue long before a desktop. I don't use them in test setups.

Bob

On Dec 1, 2012, at 11:37 PM, David davidwhess@gmail.com wrote:

On Sun, 2 Dec 2012 08:43:39 -0500, Bob Camp lists@rtty.us wrote:

When I built my most recent workstation a couple years ago, I
specifically looked for motherboards that included a COM port and
thought I had found one but when it arrived, I discovered that they
left off everything except the UART which was integrated.  Instead of
trying to figure out what level translator they used, I just bought a
PCI serial card instead.  None of the USB serial dongles I tried
worked well.

I have stopped using laptops as well.  They are too fragile even when
just sitting in one place.  I have seen a lot of old used working ones
for sale at HAM swap meets though that are inexpensive.

Hi

Strange - I must indeed have been lucky on the last dozen or so systems I built up.

Bob

On Dec 2, 2012, at 1:14 PM, David davidwhess@gmail.com wrote: