Validating a LED matrix circuit

Thread Starter


Joined Oct 25, 2020
A few days ago I decided to see if I could reverse engineer a display board just from a couple close-up pictures of it.
Two things helped - I had some passing familiarity with it as years ago, from time to time I would service the units that used this particular display, and its overall design was very similar to another display board I'd reverse engineered a couple years ago. Both boards were built around the same IC: the Intel 8279 keyboard / display controller.

I'm confident that I figured out the LED matrix itself and reasonably confident on the interface side of the 8279, but I'm a bit murky on the scanning circuit for the anode-side drivers (which uses three 74LS138s). Can someone have a look to ensure the layout makes sense?