The W78L365A is an 8-bit microcontroller which has an in-system programmable Flash EPROM for firmware updating. The instruction set of the W78L365A is fully compatible with the standard 8052.The W78L365A contains a 64K bytes of main ROM and a 4K bytes of auxiliary ROM which allows the contents of the 64KB main ROM to be updated by the loader program located at the 4KB auxiliary ROM; 256+1K bytes of on-chip RAM; four 8-bit bi-directional and bit-addressable I/O ports; an additional 4-bit port P4; three 16-bit timer/counters; a serial port. These peripherals are supported by a eight sources two-level interrupt capability. To facilitate programming and verification, the ROM inside the W78L365A allows the program memory to be programmed and read electronically. Once the code is confirmed,, the user can protect the code for security.

　　The W78L365A microcontroller has two power reduction modes, idle mode and power-down mode, both of which are software selectable. The idle mode turns off the processor clock but allows for continued peripheral operation. The power-down mode stops the crystal oscillator for minimum power consumption. The external clock can be stopped at any time and in any state without affecting the processor.