Acorn Electron Service Manual

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– Keyboard and keyboard buffer. – Serial interface, input and output, and buffers. Many of the operating system calls are vectored to enable the user to change them if required. 3.3 BASIC The BASIC interpreter is a fast implementation, very close to Microsoft standard but with numerous powerful extensions: – Long variable names. – Integer, floating point and string variables. – Multi-dimension integer, floating point and string arrays. – Extensive support for string handling. — IF...THEN...ELSE. — REPEAT...UNTIL. – Multi-line integer, floating point and string functions. – Procedures. – Local variables. – Full recursion on all functions and procedures. – Effective error trapping and handling. – Cassette loading and saving of programs and data. – Full support for the extensive colour graphics facilities. – Easy control of the built-in music generation circuits. – Built-in 6502 mnemonic assembler enabling BASIC and assembler to be mixed, or pure assembly language programs to be produced. 3.4 Power supply Transformer: Maximum AC input 264V AC Minimum AC input 216V AC Rating 14 watts Supply frequency 47 to 63Hz Power supply module: Maximum AC input 20.9V RMS Minimum AC input 17.1V RMS Maximum current +5V rail – 1.5A –5V rail – 100mA 3.5 Cassette interface Output impedance Less than 1k ohms Input impedance Greater than 100k ohms Output level Nominal 200mV peak to peak, 70mV RMS Dynamic input range Nominal 50mV to 5V peak to peak, –25 to +15dB, 0dB 350mV RMS Motor control By miniature relay within computer Contact rating 1A at 24V DC Baud rate 1200 baud using standard CUTS tones Connector 7-pin DIN socket 3.6 Video outputs Modulated output Standard 625-line PAL A UHF colour television signal Channel E36 Vision carrier Nominal 591.25MHz RF output 1.0 to 2.5mV 6db bandwidth 15 to 20MHz RF output impedance 75 ohms Connector Phono 4
Composite video Output level Nominal 1V peak to peak Output impedance Nominal 75 ohms Option Chrominance information (wire selectable) allows composite PAL monitors to be used Connector Phono Colour monitor RGB signals TTL type levels CSYNC signal TTL type level +ve/–ve going (link selectable) Connector 6-pin DIN 3.7 Audio output Loudspeaker 1.5" diameter Impedance 16 ohms Rating 0.2 watt Output power Nominal 0.1 watt maximum (from computer) Note: Sound circuit is largely independent of loudspeaker impedance. 3.8 Environment Air temperature System on: 0 to 35°C System off: –20 to 70°C Humidity System on: 85% relative humidity at 35°C System off: 95% relative humidity at 55°C Storage conditions Air temperature: –20 to 70°C Humidity: 95% relative humidity at 55°C 5
Page 3 and 4: Electron Service Manual Part no 040
Page 5: Contents 1 Introduction 1 2 Packagi
Page 8 and 9: 2 Packaging and installation The El
Page 12 and 13: 4 Disassembly and assembly To servi
Page 14 and 15: 6 The uncommitted logic array (ULA)
Page 16 and 17: 8 Fault finding inside a dead Elect
Page 18 and 19: ) If the RGB works but the UHF does
Page 20 and 21: To test the cassette input, press B
Page 22: 8.2 Oscillator 16
Page 25 and 26: 8.5 ROM 19
Page 27 and 28: 8.7 Video 21
Page 29: 8.10 Sound 23
Page 33: Electron block diagram
Page 37: Main PCB circuit diagram
Page 41: Main PCB silk-screen
Page 45: Keyboard matrix
Page 48 and 49: 18 19 890,001 Rubber foot 4 20 - 21
Page 50 and 51: 98 820,160 Crystal 16MHz 1 X1 99 10
Page 52: NOTES

Acorn Electron Service Manual

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