Types of 8051 Timers and Counters. The 8051 microcontroller mainly has two timers they are Timer 0 and Timer 1.These are used as both timers as well as counters.They are 16-bit long but the format of the microcontroller is 8-bit, due to that the Timers or counters are divided into two 8-bit parts a low byte and a high byte.Let’s see one by one,