Universal countdown timer

This universal countdown timer is good example of what can be achieved in terms of bare-bones hardware when using a powerful microcontroller like the AT89C2051 from Atmel. This 20-pin microcontroller has a 2-kBytes Flash ROM which is compatible with the 8051 Intel architecture. Here, the author has loaded the AT89C2051 with a program that simply eliminates a lot of hardware. The microcontroller is available ready-programmed from the Publishers.