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
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
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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