The Z86C21 microcontroller is a member of the Z8 singlechip microcontroller family with 8 Kbytes of ROM and 236 bytes of RAM. The device is packaged in a 40-pin DIP, 44-pin PLCC, or a 44-pin QFP with a ROMless pin option available on the 44-pin versions only. With the ROM/ ROMless feature selectively, the Z86C21 offers both external memory and preprogrammed ROM, making it wellsuited for high-volume applications or where code flexibility is required. Zilog's CMOS microcontroller offers fast execution, efficient use of memory, sophisticated interrupts, input/output bit manipulation capabilities, and easy hardware/software system expansion along with low cost and low power consumption.