Editing Commodore 64 Troubleshooting Guide (section)

=== Chip map ===

The main custom and memory ICs (Commodore service manual, boards 250407/250425/250469):

<templatestyles src="Template:StyledTable/styles.css" />
[[File:Commodore 64 (photo).jpg|thumb|right|300px|Commodore 64. Source: Wikimedia Commons.]]
{| class="wikitable styled-table" style="width:100%; text-align:left;"
! Ref !! Device !! Function
|-
| U1, U2 || 6526 CIA || Keyboard/joystick/paddle + IRQ + serial (U1); user port + serial + NMI (U2)
|-
| U3 || 2364 (901226) || BASIC ROM
|-
| U4 || 2364 (901227) || KERNAL ROM
|-
| U5 || 2364 (901225) || Character ROM
|-
| U6 || 2114 || Colour RAM
|-
| U7 || 6510 || CPU (with the parallel port P0–P5 that banks the memory map)
|-
| (8× 4164) || DRAM || 64 KB main RAM
|-
| U17 || 906114 PLA || Address decode / ROM & I/O select
|-
| U18 || 6581 (or 8580) SID || Sound (audio out pin 27, audio in pin 26)
|-
| U19 || 6567 (NTSC) / 6569 (PAL) VIC-II || Video and the system clock
|}
<ref name="c64svc">[https://portcommodore.com/rcarlsen/cbm/c64/C64_SERVICE_MANUAL.pdf Commodore C64 Service Manual] (Ray Carlsen / PortCommodore); [https://oldsilicon.com/technologies/commodore-64-250407-parts-locator/ C64 250407 Visual Parts Locator], OldSilicon; and [https://www.c64copyprotection.com/commodore-64-chip-set/ Commodore 64 Chip Set]. Source for the IC map, the PLA output-select pins (F1 pin 17 BASIC, F2 pin 16 KERNAL, F3 pin 15 character ROM, F5 pin 12 I/O) and the SID audio pins (27 out, 26 in).</ref>