GENERAL DESCRIPTION
The Z86C21 microcontroller is a member of the Z8 single-chip 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.
   
FEATURES
■ 8-Bit CMOS MCU with 8 Kbytes of ROM
■ 256 Byte Register File
    - 236 Bytes of General-Purpose RAM
    - 16 Bytes Control/Status Registers
    - 4 Bytes for Ports
■ 40-Pin DIP, 44-Pin PLCC or 44-Pin QFP Package
■ 4.5V to 5.5V Operating Range
■ Low Power Consumption: 220 mW (max) @ 16 MHz
■ Fast instruction pointer: 1.0 µs @ 12 MHz
■ Two Standby Modes: STOP and HALT
■ 32 Input/Output Lines
    FEATURES
■ Full-Duplex UART
■ All Digital Inputs are TTL Levels
■ Auto Latches
■ RAM and ROM Protect
■ Two Programmable 8-Bit Counter/Timers each with
    6-Bit Programmable Prescaler.
■ Six Vectored, Priority Interrupts from Eight Different
    Sources
■ Clock Speeds: 12 and 16 MHz
■ On-Chip Oscillator that Accepts a Crystal, Ceramic
    Resonator, LC, or External Clock Drive.