Z86C21 Datasheet, PDF (2/35 Pages) Zilog, Inc. – 8K ROM Z8 CMOS MICROCONTROLLER

GENERAL DESCRIPTION (Continued)
Z86C21 MCU
WITH 8K ROM
To unburden the program from coping with the real-time
tasks, such as counting/timing and serial data communi-
cation, the Z86C21 offers two on-chip counter/timers with
a large number of user selectable modes, and an on-board
UART.
Notes:
All Signals with a preceding front slash, "/", are active Low, e.g.,
B//W (WORD is active Low); /B/W (BYTE is active Low, only).
Power connections follow conventional descriptions below:
Connection
Circuit
Device
Power
V_CC
V_DD
Ground
GND
V_SS
Output Input
Vcc GND
XTAL /AS /DS R//W /RESET
Port 3
UART
Counter/
Timers
(2)
Interrupt
Control
ALU
FLAGS
Register
Pointer
Register File
256 x 8-Bit
Machine Timing and
Instruction Control
Prg. Memory
8192 x 8-Bit
Program
Counter
Port 2
Port 0
Port 1
I/O
(Bit Programmable)
4
4
Address or I/O
(Nibble Programmable)
8
Address/Data or I/O
(Byte Programmable)
Figure 1. Z86C21 Functional Block Diagram
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