`LCD Text Display for Linux`

When I worked at Cray Systems we had a server room full of VAX 6000 and 7000 series machines. With 187 servers in the place there wasn't much room for terminals.

Luckily for most of the machine minding stuff we didn't need them. An LCD readout on the front of the server told us what condition it was in, what jobs were running and how full the disks were. This was really useful and provided an 'at-a-glance' synopsis of what was happening without having to go to all the hassle of finding a terminal, logging in and performing system checks. I wanted the same for my Linux servers at home.

I had seen at many radio rallies some LCD displays based on the Hitachi 44780. These displays are very common and are used in all sorts of things (I have one in my washing machine) and so I bought a few at the Harwell rally.

I had seen on the Net some software that would push the system stats out of a printer port. This works well as the Hitachi chip uses parallel data to convert into a display. I went back to the Net and downloaded 4 bits of source code and set about compiling them.

When I settled down to bone up on the software I discovered instructions on how to connect the display to the printer port. The only extra bits I needed were a 10K pot for the contrast and a 5v regulator for the supply and a 25pin male D-type connector for the printer port.

I fired up the soldering iron and set about doing the mods. Half an hour later I was ready to compile the software. This was quite straight forward as anyone whom owns a Linux box will tell you.

To my surprise the software compiled with no errors. Even more to my surprise was that when I ran the software the LCD started to display stuff. If you look hard you may be able to see the writing in the picture on the right. The pictures are a bit dodgy as I don't have a macro lens for my camera.

The display shows the system time and up-time first, then shows the CPU, memory and swap space usage next. The latter is displayed for about 15 seconds and is updated during this time to give a true real-time picture of what's happening to the machine.