WITH
8K ROM
Z86C21 MCU
P
RODUCT
S
PECIFICA TION
Z86C21
8K ROM Z8
®
CMOS
M
ICROCONTROLLER
FEATURES
s
s
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
s
s
s
s
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.
s
s
s
s
s
s
s
4.5V to 5.5V Operating Range
Low Power Consumption: 220 mW (max) @ 16 MHz
Fast instruction pointer: 1.0
µs
@ 12 MHz
s
s
Two Standby Modes: STOP and HALT
s
32 Input/Output Lines
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 exter-
nal memory and preprogrammed ROM, making it well-
suited for high-volume applications or where code flexibil-
ity is required.
Zilog’s CMOS microcontroller offers fast execution, effi-
cient use of memory, sophisticated interrupts, input/output
bit manipulation capabilities, and easy hardware/software
system expansion along with low cost and low power
consumption.
The Z86C21 architecture is characterized by Zilog’s 8-bit
microcontroller core. The device offers a flexible I/O
scheme, an efficient register and address space structure,
multiplexed capabilities between address/data, I/O, and a
number of ancillary features that are useful in many indus-
trial and advanced scientific applications.
For applications demanding powerful I/O capabilities, the
Z86C21 provides 32 pins dedicated to input and output.
These lines are grouped into four ports. Each port consists
of eight lines, and is configurable under software control to
provide timing, status signals, serial or parallel
I/O with or without handshake, and an address/data bus
for interfacing external memory. There are three basic
address spaces available to support this configuration:
Program Memory, Data Memory, and 236 general-pur-
pose registers.
1
WITH
8K ROM
Z86C21 MCU
GENERAL DESCRIPTION
(Continued)
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
Power
Ground
Circuit
V
CC
GND
Device
V
DD
V
SS
Output Input
Vcc
GND
XTAL /AS /DS R//W /RESET
Port 3
Machine Timing and
Instruction Control
UART
ALU
Counter/
Timers
(2)
FLAGS
Prg. Memory
8192 x 8-Bit
Interrupt
Control
Register
Pointer
Register File
256 x 8-Bit
Program
Counter
Port 2
Port 0
Port 1
4
I/O
(Bit Programmable)
4
8
Address/Data or I/O
(Byte Programmable)
Address or I/O
(Nibble Programmable)
Figure 1. Z86C21 Functional Block Diagram
\2
WITH
8K ROM
Z86C21 MCU
PIN DESCRIPTION
VCC
XTAL2
XTAL1
P37
P30
/RESET
R//W
/DS
/AS
P35
GND
P32
P00
P01
P02
P03
P04
P05
P06
P07
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
P36
P31
P27
P26
P25
P24
P23
P22
P21
P20
P33
P34
P17
P16
P15
P14
P13
P12
P11
P10
Z86C21
DIP
31
30
29
28
27
26
25
24
23
22
21
Figure 2. 40-Pin DIP Pin Assignments
Table 1. 40-Pin DIP Pin Identification
Pin #
1
2
3
4
5
6
7
8
9
10
Symbol
V
CC
XTAL2
XTAL1
P37
P30
/RESET
R//W
/DS
/AS
P35
Function
Power Supply
Crystal, Oscillator Clock
Crystal, Oscillator Clock
Port 3, Pin 7
Port 3, Pin 0
Reset
Read/Write
Data Strobe
Address Strobe
Port 3, Pin 5
Direction
Input
Output
Input
Output
Input
Input
Output
Output
Output
Output
Pin #
11
12
13-20
21-28
29
30
31-38
39
40
Symbol
GND
P32
P00-P07
P10-P17
P34
P33
P20-P27
P31
P36
Function
Direction
Input
Input
In/Output
In/Output
Output
Input
In/Output
Input
Output
Ground
Port 3, Pin 2
Port 0, Pins 0,1,2,3,4,5,6,7
Port 1, Pins 0,1,2,3,4,5,6,7
Port 3, Pin 4
Port 3, Pin 3
Port 2, Pins 0,1,2,3,4,5,6,7
Port 3, Pin 1
Port 3, Pin 6
3
Talking
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