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Electron Motherboard Power Supply

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Mains adaptor. Click on this thumbnail to enlarge

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IC1

Ferranti 12CO21M (ULA). This is the Electron core chip, combining the BBCs 6845 CRT controller, 5C094 Video ULA, 6850 ACIA, 2C199 Serial ULA, plus most of the driving circuitry for the system memory.

IC2

HN613256 OS + Basic ROM

IC3

SY6502A CPU

IC4,5,6,7

4x TMS4164-15 DRAM

IC8

74S04N (TTL Hex inverter)

IC9

74LS169 (TTL 4-bit up/down counter)

IC10

74LS00 (TTL Quad 2-input NAND gate)

IC11

74S74 (TTL Dual D-flipflop)

IC12

74LS74 (TTL Dual D-flipflop)

IC13

LM324N (Quad OPAMP)

IC14,15,16

74LS00 (TTL Quad 2-input NAND gate)

IC17,18

Empty, used for installing the speech generator

IC19

Buffers the output from the ULA RGB signals to the rest of the machine. Thanks to Duncan Gunn for this information

IC20

64k, 8bit SIP memory module (alternative to ICs 4-7). Only on later boards.

PL1

Expansion Port

POWER IN

POWER OUT

RL1

SK1

SK2

SK3

SK4

UHF Modulator

SPEAKER

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