ZiLOG Z8 Series User Manual

Z8
®
CPU
User Manual
UM001604-0108 Address Space
6
Registers can be accessed as either 8-bit or 16-bit registers using Direct, Indirect, or
Indexed Addressing. All 236 general-purpose registers can be referenced or modified by
any instruction that accesses an 8-bit register, without the requirement for special instruc-
tions. Registers accessed as 16 bits are treated as even-odd register pairs (there are 118
valid pairs). In this case, the data’s most significant byte (MSB) is stored in the even num-
bered register, while the least significant byte (LSB) goes into the next higher odd num-
bered register. See Figure 2.
By using a logical instruction and a mask, individual bits within registers can be accessed
for bit set, bit clear, bit complement, or bit test operations. For example, the instruction
AND R15, MASK performs a bit clear operation, Figure 3 on page 7 displays this
example.
F4 T0 Timer/Counter 0
F3 PRE1 T1 Prescaler
F2 T1 Timer/Counter 1
F1 TMR Timer Mode
F0 SIO Serial I/O
EF R239
General-Purpose Registers (GPR)
04 R4
03 P3 Port 3
02 P2 Port 2
01 P1 Port 1
00 P0 Port 0
Figure 2. 16-Bit Register Addressing
Table 2. Z8 Standard Register File (Continued)
Hex Address
Register
Identifier Register Description
MSB
LSB
Rn Rn+1
n = Even Address

ZiLOG Z8 Series Specifications

General

Brand	ZiLOG
Model	Z8 Series
Category	Microcontrollers
Language	English

Summary

Address Space

Z8 CPU Standard Register File

Details the standard register file structure, including I/O, general-purpose, and control registers.

Z8 Expanded Register File (ERF)

Reset

Reset Pin, Internal POR Operation

Explains the function of the RESET pin and internal Power-On Reset for chip initialization.

Watchdog Timer

Watchdog Timer

Describes the retriggerable one-shot timer that resets the CPU if it reaches its terminal count.

Counters and Timers

TIN Modes

Interrupts

Interrupt Sources

Lists interrupt types, sources, and vectors available in the Z8 family processors.

Interrupt Initialization

Power-Down Modes

Halt Mode Operation

Explains HALT mode, suspending execution while keeping the oscillator active.

Stop Mode Operation

Details STOP mode for lowest standby current by turning off internal clocks.

Serial Input/Output

UART Introduction

SPI Operation

Details SPI usage in master and slave modes, including data transfer and chip select.

External Interface

Introduction

External Addressing Configuration

Instruction Set

Processor Flags

Condition Codes

Instruction Description

Provides detailed descriptions of Z8 instructions, including syntax, operation, and flags.