Z86L972 Datasheet, PDF (8/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
1
Architectural Overview
The Z86L972/Z86L973/Z86L974 family is designed to be used in a wide variety of
embedded control applications including home appliances, infrared (IR) remote
controls, security systems, and wireless keyboards.
It has three counter/timers, a general-purpose 8-bit counter/timer with a 6-bit pres-
caler and an 8-bit/16-bit counter/timer pair that can be used individually for gen-
eral-purpose timing or as a pair to automate the generation and reception of
complex pulses or signals. Unique features of the Z86L972/Z86L973/Z86L974
family of products include 489 bytes of general-purpose random-access memory
(RAM), 256 bytes of which are mapped into the program memory space and can
be used to store data variables or as executable RAM, a low-battery detection
flag, and a controlled current output pin, which is a regulated current source that
sinks a predefined current (I_CCO). Table 1 highlights the basic product features of
these microcontrollers.
Table 1. Z86L972/Z86L973/Z86L94 Comparison
Z86L972
Z86L973
Z86L974
ROM
4K
8K
16K
The Z8 microcontroller core offers more flexibility and performance than accumu-
lator-based microcontrollers. All 256 general-purpose registers, including dedi-
cated input/output (I/O) port registers, can be used as accumulators. This unique
register-to-register architecture avoids accumulator bottlenecks for high code effi-
ciency. The registers can be used as address pointers for indirect addressing, as
index registers, or for implementing an on-chip stack.
The Z8 has a sophisticated interrupt structure and automatically saves the pro-
gram counter and status flags on the stack for fast context-switching. Speed of
execution and smooth programming are also supported by a “working register
area” with short 4-bit register addresses.
The Z8 instruction set, consisting of 43 basic instructions, is optimized for high-
code density and reduced execution time. It is similar in form to the ZiLOG Z80
instruction set. The eight instruction types and six addressing modes together with
the ability to operate on bits, 4-bit nibbles or binary coded decimal (BCD) digits, 8-
bit bytes, and 16-bit words, make for a code-efficient, flexible microcontroller.
PS010504-1002
PRELIMINARY