Editing Acorn Electron (section)

== Main board components ==

IC designators are from the Service Manual parts list.<ref name="sm" />

{| class="wikitable styled-table" style="width:70%; text-align:center;"
! Component !! Device !! Designator !! Notes
|-
| '''CPU''' || 6502A (Synertek SY6502A / Rockwell R6502AP) || IC3 || Clock stoppable by the ULA
|-
| '''ULA''' || Ferranti 12C021 || IC1 || 68-pin, in a holder (Issue 1&ndash;4)
|-
| '''RAM''' || 4× 4164 (64K×1 DRAM) || IC4&ndash;IC7 || 32 KB; 4-bit-wide
|-
| '''ROM''' || Single 32 KB mask ROM || IC2 || MOS 1.0 + BBC BASIC II
|-
| '''Clock''' || 16 MHz crystal oscillator || IC8 (74S04) || Divided by the ULA
|-
| '''Cassette/audio amp''' || LM324 || IC13 || Needs +5 V and &minus;5 V
|-
| '''Sync logic''' || 74LS86 || IC14, IC15 || RGB / CSYNC generation
|}

=== The ULA ===

The ULA (IC1) coordinates the whole machine in a 68-pin package. Its pins include the data lines to/from RAM (controlled by RAS/CAS/WE), the multiplexed RAM address lines, the keyboard inputs (KBD0&ndash;3), the 16&nbsp;MHz clock input, the cassette CAS&nbsp;IN/CAS&nbsp;OUT (1.8&nbsp;V&nbsp;p-p), the sound output, the processor address/data lines, IRQ, NMI (used by the ULA to arbitrate RAM access), R/W, the ROM-select output and RST (asserted at power-up and when BREAK is pressed).<ref name="sm" />