Sinclair ZX Spectrum Service Manual

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
7
1 INTRODUCTION
Introduction
Architecture
Z80A CPU
Memory Organisation
Read/Write Operations
Input/Output
TV Picture Generation
Keyboard Scanning
Tape Interface
Power Supplies
1.1 INTRODUCTION
A block diagram of the complete ZX Spectrum micro-computer is given below. It is valid for all build
standards, fitted with either 16k or 48k bytes of dynamic RAM memory. Although functionally identical,
detailed circuit changes have been introduced to improve reliability and to assist with manufacture. The
printed circuit board layout has also been modified. Details of these changes are highlighted where
necessary in the following paragraphs, and in later sections referring to fault diagnosis and repair.

Sinclair ZX Spectrum Specifications

General

Processor	Zilog Z80A
Clock Speed	3.5 MHz
RAM	16KB or 48KB
ROM	16KB
Graphics	256 x 192 resolution
Sound	1-channel beeper
Storage	Cassette tape
Input	Keyboard
Power	9V DC
Release Year	1982
Display	TV via RF modulator
Ports	Expansion, RF
Colors	15 (8 colours with two levels of brightness each, plus black)