Editing Commodore 64 (section)

==== Internal hardware ====
* Microprocessor CPU:
** [[MOS Technology 6510]]/8500 (the 6510/8500 is a modified [[MOS Technology 6502|6502]] with an integrated 6-bit I/O port)
** Clock speed: {{nowrap|0.985 MHz ([[PAL]])}} or {{nowrap|1.023 MHz ([[NTSC]])}}
* Video: [[MOS Technology VIC-II]] 6567/8562 (NTSC), 6569/8565 (PAL)
** 16 colors<ref name="the-commodore-zone.com">{{cite web|url=http://www.the-commodore-zone.com/articlelive/articles/88/6/Software-Superstars/Page6.html |title=Software Superstars |website=The-commodore-zone.com |date=December 5, 2007 |access-date=March 18, 2017}}</ref><!--to be listed-->
** Text mode: 40×25 characters; 256 user-defined chars (8×8 [[pixel]]s, or 4×8 in multicolor mode); or extended background color; 64 user-defined chars with 4 background colors, 4-bit color RAM defines foreground color
** Bitmap modes: 320×200 (2 unique colors in each 8×8 pixel block),<ref name="Rautiainen">{{cite web| url=http://www.devili.iki.fi/Computers/Commodore/C64/Programmers_Reference/Chapter_3/page_123.html |title=Programmers_Reference|last=Rautiainen|first=Sami|access-date=March 23, 2011}}</ref> 160×200 (3 unique colors + 1 common color in each 4×8 block)<ref name="Rautiainen"/>
** 8 hardware [[sprite (computer graphics)|sprites]] of 24×21 pixels (12×21 in multicolor mode)
** Smooth scrolling, [[raster interrupt]]s
* Sound: [[MOS Technology SID|MOS Technology 6581/8580 SID]]
** 3-channel{{r|the-commodore-zone.com}} [[synthesizer]] with programmable [[ADSR envelope]]
** 8 [[octave]]s
** 4 [[waveform]]s per audio channel: [[Triangle wave|triangle]], [[Sawtooth wave|sawtooth]], [[Square wave (waveform)|variable pulse]], [[white noise|noise]]
** [[Oscillator sync]]hronization, [[ring modulation]]
** Programmable filter: [[high-pass filter|high pass]], [[low-pass filter|low pass]], [[band-pass filter|band pass]], [[Band-stop filter|notch filter]]
* Input/Output: Two [[MOS Technology CIA|6526 Complex Interface Adapters]]
** 16 bit parallel I/O
** 8 bit serial I/O
** 24-hours (AM/PM) Time of Day clock (TOD), with programmable [[alarm clock]]<ref>{{cite web|url=http://www.6502.org/documents/datasheets/mos/mos_6526_cia.pdf |archive-url=https://web.archive.org/web/20081204114028/http://www.6502.org/documents/datasheets/mos/mos_6526_cia.pdf |archive-date=2008-12-04 |url-status=live|title=MOS 6526 CIA datasheet (PDF format)|website=6502.org}}</ref>
** 16 bit interval timers
* RAM:
** 64&nbsp;KB, of which 38&nbsp;KB were available for BASIC programs
** 1024 [[nybble]]s{{r|prg|p=262}} color RAM (memory allocated for screen color data storage)<ref name="Rautiainen_Service_Manual">{{cite web| url=http://www.devili.iki.fi/Computers/Commodore/C64/Service_Manual/Page_08.html |title=Service_Manual: RAM Control Logic.|last=Rautiainen|first=Sami|access-date=March 13, 2011}}</ref>
** Expandable to 320&nbsp;KB with [[Commodore REU|Commodore 1764]] 256&nbsp;KB [[Commodore REU|RAM Expansion Unit]] (REU); although only 64&nbsp;KB directly accessible; REU used mostly for the [[GEOS (8-bit operating system)|GEOS]]. REUs of 128&nbsp;KB and 512&nbsp;KB, originally designed for the C128, were also available, but required the user to buy a stronger power supply from some third party supplier; with the 1764 this was included.
[[Creative Micro Designs]] also produced a 2&nbsp;[[megabyte|MB]] REU for the C64 and C128, called the 1750&nbsp;XL. The technology actually supported up to 16&nbsp;MB, but 2&nbsp;MB was the biggest one officially made. Expansions of up to 16&nbsp;MB were also possible via the CMD [[SuperCPU]].
* ROM:
** {{nowrap|20 KB}} ({{nowrap|9 KB}} [[Commodore BASIC]] 2.0; {{nowrap|7 KB}} [[KERNAL]]<!-- the BASIC continues into the upper ROM chip-->; {{nowrap|4 KB}} character generator, providing two {{nowrap|2 KB}} character sets)