8-bit CMOS Microcontroller
DIP8 +---\/---+ Vdd | 1 40| Vss GP5/OSC1/CLKIN | 2 39| GP0 GP4/OSC2 | 3 38| GP1 GP3/*MCLR/Vpp | 4 37| GP2/T0CKI +--------+
DIP8
Set reader to FREQ, put black probe to GND, red probe to 2 and 3 to measure CPU clock
12C5xx Datasheet