Commodore 65
Gallery
Commodore 65 prototype computer
The elusive Commodore 65 prototype, a rare collector's item.
Commodore 65 motherboard detail
The C65's advanced prototype motherboard with custom chips.
Commodore 65 prototype documentation
Development documentation and specifications for the unreleased C65.
Commodore 65 (C65)
“The C65 was the computer that could have been. It was Commodore’s attempt to create a true successor to the C64, with 16-bit power while maintaining backward compatibility. It’s one of the great ‘what ifs’ of computing history.” - Bil Herd, Commodore Engineer
The Commodore 65 (C65) was a prototype computer developed by Commodore in the early 1990s as a successor to the immensely popular Commodore 64. Although it never reached full production, the C65 has become one of the most sought-after collector’s items in computing history, with only a handful of prototypes known to exist today.
The Computer That Never Was
Developed under the code name “64DX” or “Commander 65,” the C65 was intended to be a high-end 8-bit computer with some 16-bit features, designed to compete with early 16-bit systems while maintaining compatibility with the vast C64 software library.
Why the C65 Was Special
- Advanced Graphics: 256 colors from a palette of 4096
- Improved Sound: Enhanced SID chip with 8 voices
- Faster CPU: 3.54 MHz 65CE02 (compatible with 6502/6510)
- More Memory: 128KB RAM (expandable to 8MB)
- Built-in 3.5” Drive: 1.76MB capacity (880KB per side)
Technical Specifications
Technical Specifications
- CPU
- CSG 65CE02 @ 3.54 MHz
- Memory
- 128 KB RAM (expandable to 8MB) + 128 KB ROM
- Graphics
- CSG 4567 VIC-III - 640×400, 256 colors from 4096, 8 sprites
- Sound
- CSG 8580 SID + 2× CSG 8580 SID (3× SID chips total, 8 voices)
- Storage
- Built-in 3.5" DD floppy drive (1.76MB), optional external drives
- Ports
- Cartridge, floppy, serial, user, 2× joystick, TV/RF, RGB, power
- Operating System
- Commodore BASIC 10.0
Design and Features
Physical Design
- Case: Similar to C64C but with a built-in 3.5” drive
- Keyboard: Full-travel with numeric keypad and function keys
- Ports: Similar to C128 but with enhanced capabilities
- Power Supply: External brick design
Graphics Capabilities
- Resolutions: 320×200, 640×200, 640×400
- Colors: 256 on screen from 4096 palette
- Sprites: 8 hardware sprites with collision detection
- Scrolling: Smooth hardware scrolling
- Blitter: For fast graphics operations
Sound System
- Three SID Chips: 8 independent voices
- Stereo Sound: Left/right channel separation
- Filters: Programmable audio filters
- Waveforms: Multiple waveform options per voice
The C65 Experience
For C64 Users
- Backward Compatibility: Nearly 100% C64 compatibility
- Faster Loading: 3.5” floppy and faster serial bus
- Enhanced BASIC: New commands and features
- More Memory: For larger programs
For Programmers
- BASIC 10.0: Significant improvements over BASIC 7.0
- Machine Language: Full access to new hardware
- Development Tools: Built-in monitor and debugger
- Documentation: Extensive technical documentation
For Gamers
- Better Graphics: More colors and higher resolution
- Enhanced Sound: More channels and effects
- Faster Performance: Smoother gameplay
- New Games: Titles taking advantage of the hardware
Technical Deep Dive
CPU and Memory
- 65CE02: Enhanced 6502 with new instructions
- Memory Map:
- $0000-$1FFF: RAM (8KB)
- $2000-$9FFF: RAM (32KB)
- $A000-$BFFF: ROM or RAM
- $C000-$FFFF: ROM or RAM
- MMU: Memory Management Unit for bank switching
Video System
- VIC-III: New graphics chip
- Display Modes:
- 320×200, 256 colors
- 640×200, 16 colors
- 640×400, 16 colors
- Character Modes: Text and bitmap modes
- DMA: Direct Memory Access for fast operations
Storage System
- 3.5” Floppy: 1.76MB capacity
- 1581 Compatibility: Could read/write 1581 disks
- Faster Serial Bus: Improved transfer speeds
- Hard Drive Support: Via expansion
The C65 Legacy
Why It Was Cancelled
- Market Changes: Shift to 16/32-bit computing
- Internal Politics: Management changes at Commodore
- Cost: Would have been expensive to produce
- Timing: Released too late in the 8-bit lifecycle
Prototype Status
- Quantity: Approximately 50-200 units produced
- Completeness: Near-production ready
- Variants: Several motherboard revisions exist
Collector’s Item
- Rarity: Extremely rare
- Value: $10,000-$50,000+ at auction
- Clones: FPGA recreations available
Notable Software
Built-in Software
- BASIC 10.0: Enhanced BASIC interpreter
- Monitor: Machine language monitor
- Disk Utilities: For managing files
Homebrew
- Games: New titles developed by enthusiasts
- Demos: Showcasing the hardware
- Tools: Development utilities
Technical Notes for Enthusiasts
Known Issues
- Incompatibilities: Some C64 software doesn’t run correctly
- Stability: Prototype hardware can be unstable
- Documentation: Limited technical information
Modern Projects
- C65GS: FPGA implementation
- MEGA65: Modern reimagining
- Emulation: VICE and other emulators
The C65 Today
Emulation
- VICE: Accurate C65 emulation
- MEGA65: FPGA-based recreation
- Other: Various emulation projects
Community
- Forums: Active discussion groups
- Preservation: Efforts to document the hardware
- Development: New software and hardware
Did You Know?
- The C65 was code-named “64DX” during development
- Some C65 prototypes were sold at a liquidation auction in 1995
- The C65’s BASIC 10.0 included commands for its advanced graphics and sound
- A few C65s were used in television production after Commodore’s demise
- The C65’s design influenced later Commodore products, including the unreleased C64GS II
The C65 in Popular Culture
- Featured in the documentary “From Bedrooms to Billions”
- Mentioned in retro computing books and magazines
- The subject of numerous YouTube videos and articles
- Inspired the creation of the MEGA65 project