Previous VMW Meter Designs

This page is an archive of previous attempts to get an Alpha-numeric CPU meter going. See my ongoing work on the same project here.

Back in 1998 I had hoped to find a readily-available LED driver that could handle a 14-segment display, hopefully with multiplexing and other nice features. At the time I could not find spec sheets for anything except 7-segment drivers. Thus I decided to do things the hard way.

The prototype used 7400 series logic (there were flip flop arrays to store state, serial/parallel converters to take the info from the PC over the parallel port, and a 555 timer to run the multiplexer).

Here are some pictures (circa 2001). It is displaying a "W" on the alphanumeric LED. It is programmed via the parallel port into a 16-bit shift register.

Here some of the register-set RAM is hooked up. It is displaying an "M".

Here multiplexing is working and lighting up 2 digits at once. It's hard to see but it is saying "OK".

Sadly I ran out of time and the project languished for years. I only recently (in 2010) removed all of the parts from the above pictured breadboards, and re-implementing things using an LED driver chip (see here).
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