Now you see what I did last week. (Linux my timedummy load) 
(or TIME>/dev/null)
So this is the result of what I did...
I found a copy of Joseph W. Vigneau's CPU-Meter on my new Linux CD-Rom 
which can be connected to the printer port and shows the CPU activity in 
a bar graph like fashion.
But there was a problem:
I liked it very much to have a cpu-meter but I need all of my
printer ports and, considering the AS/400 which has the meter on the
front, it would be very nice to replace the MHz display by a CPU meter.
This was the reason to develop an interface card for the cpu-meter.
Another reason was that I needed some I/O-Ports for experimentation
(switching devices on and off - for example my second Linuxcomputer 
and my printer - or read something in like powerfail signals from
an UPS (my old one has no interface build in) etc.).

The interface card's current version is a very early release. My next
project is a LC-Display to print all the status messages to a device
different from my screen (because some people work on this machine and
produce messages like: paper out on some printer or disk error messages).

I have designed the board as simple as possible (for easy rebuilding for
everyone everywhere) I think it must be possible to get the 74LS..
ICs everywhere.

If you need more I/O bits, it is easy to add ports: 
You can add additional 74LS373's for more output bits) 
(you must connect the next free (13, 12, ...) output 
pin to the enable latch pin (11) of the new 74LS373 via an inverter (there 
is a 74LSxx with 4 free inverters, please look in some databook for more 
information about the layout)).
For more input bits you have to add a 74LS138 (connect it 
like the one that is already in the circuit but connect /IOR instead of 
/IOW on pin 5) and use a 74LS244 to get the data from the input to the 
IO-databus.

- or -

You wait until I included it in the next version. :-)

The IO-Address is selectable with a jumper block.
I use the IO-Address 0x280 (but be careful, it is used by some ethernet 
cards).

The jumper setting for 0x280 is: OPEN CLOSE OPEN CLOSE CLOSE CLOSE CLOSE
                                 |                                  |
                                 |---connected to pin 18 of 74LS521 | 
                                                                    |
                                                                  pin 5

If you want to use a different IO-Address here is how you calculate it:
Take you favourite IO-Address, convert it to binary, shift it to the 
right 3 times and take a "0" as CLOSE and a "1" as OPEN. Take the last
seven digits for your jumper block.

Example:
0x280 in binary is 0010 1000 0000
shift right 3x:    ---0 0101 0000
the jumper block: OPEN CLOSE OPEN CLOSE CLOSE CLOSE CLOSE 

Now you have to change the IO-Address: start make config and
set the new IO-address (decimal) 

The devicedriver for this board uses two minor device numbers in this
version. /dev/led0 is the bar graph display and /dev/led1 is free to be 
used with six LEDs (they have to be created with mknod /dev/led0 30 0
and mknod /dev/led1 30 1).

Note: I have no information who gives out the devicenumbers for new 
      devices so I decided to use 30 because it was the next free one in 
      /usr/include/linux/major.h (to avoid any conflict look there).

For more information see ledtest.c and led2.c (two simple programs for
testing).

Use linux-1.2.0.led.diff from directory /usr/src to patch the kernel
(it searches for the kernel in ./linux).

The device driver was tested with kernel version 1.1.92 and 1.2.0.

Installation instructions:

1. untar ledportcard.tgz
2. cd to /usr/src
3. patch -p </usr/src/led/linux-1.2.0.led.diff
   (assuming that you untared ledportcard.tgz to /usr/src/led)
4. cd to /usr/src/linux and run make config (set "LED-port-card support" to
   "y"). Then you can recompile the kernel.
5. to see the CPU meter start the meter program.
6. Have fun! (don't end up staring at the CPU meter..)

Next time there will also be better documentation!

Alexander Tietzel 

any comments are appreciated 
E-Mail to: christian.staege@clipper.de (a friend of mine)
