The PIC16F628A is an 18 pin, flash based, 8 bit microcontroller. This device employs an advanced RISC architecture. The PIC16F628A-I/P has enhanced core features, an eight level deep stack, and multiple internal and external interrupt sources. The separate instruction and data buses of the Harvard architecture allow a 14 bit wide instruction word with the separate 8 bit wide data. The two stage instruction pipeline allows all instructions to execute in a single cycle, except for program branches (which require two cycles). A total of 35 instructions (reduced instruction set) are available, complemented by a large register set.