STC89xx series, which is produced by STC MCU Limited, is a 8-bit single-chip microcontroller with a fully
compatible instruction set with industrial-standard 80C51 series microcontroller. There is 64K bytes flash
memory embeded for appliaction program, which is shared with In-System-Programming code.In-SystemProgramming (ISP) and In-Application-Programming (IAP) support the users to upgrade the program and data
in system. ISP allows the user to download new code without removing the microcontroller from the actual end
product;IAP means that the device can write non-valatile data in Flash memory while the application program
is running. There are 1280 bytes or 512 bytes on-chip RAM embedded that provides requirement from wide
field application. The user can configure the device to run in 12 clocks per machine cycle, and to get the same
performance just as he uses another standard 80C51 device that is provided by other vendor, or 6 clocks per
machine cycle to achieve twice performance. The STC89xx series retain all features of the standard 80C51. In
addition, the STC89xx series have a extra I/O port (P4 ), Timer 2, a 8-sources, 4-priority-level interrupt structure,
on-chip crystal oscillator,and a one-time enabled Watchdog Timer.