Description: At the same time compatible with AT, STC series MCU Single chip microcomputer 40 IO pinout With self-locking switch, it is convenient to switch the power on and off With power indicator LED 3.5mm*1.3mm external power supply The pin header leads out 3 way VCC and GND, can input or output power Pull-up resistor P0 has been pulled up With RC and manual reset circuit Support ISP download and serial download program Integrated ISP 10P download interface, easy to download AT89S52 microcontroller. Below the crystal oscillator is a round hole socket, easy to replace the crystal two types of power input methods: DC power socket (supporting carrier is 3.5mm*1.3mm) and single-row pin (next to power switch) With a programmable LED, can do LED experiments 40P locking seat, easy to replace the SCM chip, batch processing, eliminating the need for hands-on welding trouble Specification: Material: PUC sheet Size: 90*40*18mm/3.54*1.57*0.71'' Package Includes: 1x 51 Development Board (4 Pack)