The instruction set of the W78E516D/W78E058D is fully compatible with the standard 8052. The W78E516D/W78E058D series contains a 64K/32K bytes of main Flash EPROM and a 4K bytes of auxiliary Flash EPROM which allows the contents of the 64K/32K bytes main Flash EPROM to be updated by the loader program located in the 4K bytes Flash EPROM; a 256 bytes of SRAM; 256 bytes of AUXRAM; 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 an 8 sources 2-level interrupt capability. To facilitate programming and verification, the Flash EPROM inside the W78E516D/W78E058D series allows the program memory to be programmed and read electronically. Once the code is confirmed, the user can protect the code for security.
The W78E516D/W78E058D series 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.