Hardware / Atari and Commodore
The Competition
(Commodore)
Two generations of rivalry: the Atari 800 meets the Commodore 64, and the Atari ST meets the Amiga. A look inside the machines that gave Atari owners so much to debate.
Comparisons cover standard hardware, with regional and revision differences noted. Display figures describe normal modes; software tricks and expansion hardware can push these machines further.
01 / The 8-bit rivalry
Atari 800 vs. Commodore 64
The Atari 800 arrived in 1979; the Commodore 64 followed in 1982. Atari already had a sophisticated graphics architecture when Commodore brought more standard memory, eight sprites, and the distinctive SID synthesizer to the contest.
Trying the other machine? Read C64 for Atari 800 users for disk commands, directory listings, loading programs, and keyboard tips.
On a small screen, scroll the table sideways to compare both machines.
| Hardware | Atari 800 | Commodore 64 |
|---|---|---|
| CPU | 6502-family processor; about 1.79 MHz NTSC or 1.77 MHz PAL. | 6510; about 1.02 MHz NTSC or 0.99 MHz PAL. |
| RAM | Modular memory, up to 48 KB in the standard configuration; installed RAM varied. | 64 KB standard; ROM and I/O overlap parts of the address space. BASIC starts with 38,911 bytes free. |
| Graphics chips | ANTIC display processor plus CTIA, or GTIA in later machines. | VIC-II handles the display, scrolling, and sprites. |
| Bitmap display | Typical full-screen modes include 320 × 192 with two luminance levels of one hue, and 160 × 192 with four colors. | 320 × 200 with two colors per 8 × 8 cell; 160 × 200 multicolor with four colors per cell, including a shared background. |
| Color choices | 128 color-register combinations. GTIA adds 80 × 192 modes with nine selected colors, 16 hues, or 16 shades of one hue. | Fixed palette of 16 colors. All can appear on screen, subject to each mode’s cell restrictions. |
| Moving objects | Four 8-bit-wide players and four 2-bit-wide missiles; height defined by the display data. | Eight 24 × 21-pixel sprites, or 12 × 21 multicolor sprites; hardware size doubling available. |
| Sound | POKEY: four tone/noise channels; channels can be paired for finer pitch control. | SID: three synthesizer voices with selectable waveforms, envelopes, and a shared programmable filter. |
| Storage | External cassette recorder and disk drives through SIO; cartridges. | External Datasette, serial disk drives such as the 1541, and cartridges. |
| Ports & expansion | Four controller ports, two cartridge slots, SIO, monitor output, and TV output. | Two controller ports, cartridge expansion, user port, serial bus, cassette, audio/video, and TV output. |
| BASIC | Atari BASIC on a cartridge; graphics and sound commands built into the language. | Commodore BASIC V2 in ROM; graphics and sound generally controlled through POKE commands. |
Where Atari stands out
ANTIC’s display lists describe how to build the screen, making mixed text and graphics modes and smooth scrolling natural parts of the design. Four controller ports also make the original 800 well suited to multiplayer games.
Where Commodore stands out
The C64 supplies more RAM as standard, wider independent sprites, and detailed control over musical timbre through SID. Those features offer a strong foundation for games and music.
Reading the numbers
CPU clock speed alone does not predict game speed: display hardware takes memory cycles on both machines. GTIA’s often quoted 256-color capability is a hue-and-luminance range, not 256 freely chosen colors in a normal screen mode. Software can change display settings during a frame on both systems.
02 / The 1985 generation
Atari ST vs. Amiga
The original Atari 520ST and Commodore Amiga 1000 both arrived in 1985 with Motorola 68000 processors and mouse-driven desktops. They show two different approaches to the next generation of personal computing.
On a small screen, scroll the table sideways to compare both machines.
| Hardware | Atari 520ST | Amiga 1000 |
|---|---|---|
| CPU | Motorola 68000 at 8 MHz. | Motorola 68000 at about 7.16 MHz NTSC or 7.09 MHz PAL. |
| RAM | 512 KB standard. | 256 KB standard Chip RAM, expandable to 512 KB with the front memory module; additional external expansion possible. |
| Custom hardware | Shifter video chip, GLUE logic, MMU, and DMA controller; no blitter in the original 520ST. | Agnus, Denise, and Paula; includes a blitter for block graphics operations and a Copper display coprocessor. |
| Standard color modes | 320 × 200 with 16 colors, or 640 × 200 with four, from a palette of 512. | NTSC: 320 × 200 with up to 32 colors, or 640 × 200 with up to 16, from a palette of 4,096. |
| High resolution | 640 × 400 monochrome, non-interlaced, with a compatible high-resolution monitor. | NTSC interlace reaches 640 × 400; PAL normally offers 256 lines, or 512 interlaced. Interlace can visibly flicker. |
| Special graphics | Original hardware has no sprite engine; software draws moving objects. | Eight hardware sprites, hardware scrolling, and HAM (Hold-And-Modify) mode for up to 4,096 colors with neighboring-pixel constraints. |
| Sound | YM2149: three tone channels plus a noise generator; mono output. | Paula: four 8-bit sampled-audio channels, arranged as two channels on each stereo side. |
| Floppy storage | External 3½-inch drive; SF354 holds 360 KB, SF314 holds 720 KB. The original 520ST has no built-in drive. | Built-in double-sided 3½-inch drive, storing 880 KB per Amiga-formatted disk. |
| Ports & expansion | Built-in MIDI in/out, serial, parallel, mouse/joystick, monitor, external floppy, ACSI DMA, and cartridge ports. | Serial, parallel, two mouse/joystick ports, RGB/composite video, stereo audio, external floppy, and expansion bus; MIDI needs an interface. |
| System software | TOS with GEM desktop. The earliest units loaded TOS from disk; ROM TOS followed. | Kickstart loads from disk into dedicated 256 KB writable control-store memory, separate from main RAM; Workbench provides the desktop and the OS supports preemptive multitasking. |
Where Atari stands out
Built-in MIDI makes connecting musical instruments straightforward. The 640 × 400 monochrome display provides a sharp, stable workspace for text and desktop applications. Its CPU also has the higher clock rate of this pair.
Where Amiga stands out
The blitter and Copper take graphics work off the CPU, while sampled stereo sound and the larger palette give artists and game developers more options. Its multitasking operating system can keep several programs running.
Comparing the original machines
These are the 520ST and A1000, not later STE or AGA-equipped Amiga models. HAM is useful for richly colored pictures but constrains adjacent pixels. Extra-Half-Brite mode is omitted from the baseline because early NTSC A1000 hardware lacks it. Faster animation still depends on how well software uses each machine.