Commodore 128

Released: January 1985 Original Price: $299.95

Gallery

Commodore 128 computer
Commodore 128 computer The Commodore 128 in all its glory, featuring a full-travel keyboard and dual-processor design.
C128 keyboard detail
C128 keyboard detail The C128's keyboard featured 92 keys with four cursor keys and a numeric keypad.
C128 system setup
C128 system setup A complete C128 setup with monitor and dual disk drives, showing its business-oriented design.

Commodore 128

“The Commodore 128 was a Swiss Army knife in a world of single-blade pocket knives. It wasn’t just three computers in one—it was a statement that Commodore was serious about the future of computing.” - Bil Herd, Lead Engineer of the C128

The Commodore 128 (C128) was Commodore’s last 8-bit home computer, released in January 1985. Marketed as “The Power to Command,” it was one of the most technically sophisticated 8-bit computers ever produced, featuring three operating modes in one machine: C128 mode, C64 mode, and CP/M 3.0 compatibility.

A Computer of Firsts

The C128 was groundbreaking for several reasons:

  • First home computer with 128KB of RAM
  • First with a full-travel keyboard and separate numeric keypad
  • First with a built-in machine language monitor
  • First with a Z80 processor for CP/M compatibility
  • First with 80-column display capability (with RGBI monitor)

Technical Specifications

Technical Specifications

CPU
MOS 8502 @ 2 MHz (1 MHz in C64 mode) + Z80 @ 4 MHz (CP/M mode)
Memory
128 KB RAM (bank-switched) + 72 KB ROM (including BASIC 7.0 & KERNAL)
Graphics
VIC-II (40/80 columns, 320×200, 16 colors) + VDC (640×200, 16 colors in 80-column mode)
Sound
SID 6581 (3 channels, 4 waveforms, filter, ADSR)
Storage
1571 Floppy Drive (5.25", 360KB), 1581 (3.5", 800KB), Datasette
Ports
Cartridge, tape, serial, user, RGBI, TV/RF, composite, 2× joystick, power
Operating System
Commodore BASIC 7.0, C64 KERNAL, CP/M 3.0

Three Computers in One

1. C128 Mode

  • Full 128KB RAM
  • 80-column display (with RGBI monitor)
  • Advanced BASIC 7.0
  • Built-in machine language monitor
  • 2 MHz processing speed

2. C64 Mode

  • Full hardware compatibility with C64
  • Access to thousands of existing games and applications
  • Uses original C64 BASIC 2.0

3. CP/M Mode

  • Runs CP/M 3.0 business software
  • Z80 processor at 4 MHz
  • Access to thousands of CP/M applications
  • 80-column display support

The C128 Experience

For Business Users

  • Professional keyboard with numeric keypad
  • 80-column text for word processing and spreadsheets
  • CP/M compatibility for business software
  • Dual floppy drive support

For Programmers

  • Built-in machine language monitor
  • BASIC 7.0 with sound and graphics commands
  • Structured programming constructs
  • Sprite and character set editors

For Gamers

  • Full C64 compatibility
  • Some games took advantage of the extra RAM
  • Faster disk access in C128 mode
  • Better keyboard for text adventures

Technical Deep Dive

Memory Architecture

  • Bank 0: 64K (shared with VIC-II)
  • Bank 1: 64K (accessible when VIC-II isn’t using the bus)
  • ROM: 32K BASIC + 32K KERNAL + 8K character ROM
  • I/O Area: Memory-mapped I/O registers

Video Capabilities

  • 40-column mode: 320×200, 16 colors, 8 sprites
  • 80-column mode: 640×200, 16 colors (via separate VDC chip)
  • RGBI output: For sharp 80-column display
  • Composite/RF: For standard TVs

Sound Features

  • Same SID chip as C64
  • Stereo sound possible with expansion
  • Four-voice synthesis with ring modulation
  • Programmable filters

The C128 Legacy

Commercial Success

  • Sold over 5 million units
  • Popular in schools and businesses
  • Strong following in Europe and South America

Technical Influence

  • Demonstrated the potential of 8-bit computing
  • Inspired later multi-mode computers
  • Showcased the value of backward compatibility

Collector’s Item

  • Highly sought after by retro computing enthusiasts
  • Active development of new software continues
  • Strong community support

Notable Software

C128 Native

  • GEOS 128: Advanced graphical environment
  • SuperCPU: 20 MHz accelerator
  • ProTerm 128: Terminal program
  • SpeedScript 128: Word processor

CP/M Software

  • WordStar: Word processing
  • dBase II: Database
  • SuperCalc: Spreadsheet
  • Multiplan: Spreadsheet

Technical Notes for Enthusiasts

Hardware Revisions

  1. Original C128 (1985): First release, 8502 CPU
  2. C128D (1986): Desktop version with built-in 1571 drive
  3. C128DCR (1988): Cost-reduced version

Common Issues

  • PLA Chip: Can fail and cause system instability
  • SID Chip: Same issues as C64
  • Power Supply: Original PSUs can fail and damage the computer

Modern Upgrades

  • RAM Expansion: Up to 2MB with modern expansions
  • Storage: SD card solutions like the 1541 Ultimate
  • Networking: Ethernet and WiFi interfaces

The C128 Community Today

User Groups

  • Active communities on forums and social media
  • Annual Commodore conventions
  • Local user groups worldwide

New Development

  • Homebrew games and demos
  • Hardware expansions
  • Development tools and compilers

Emulation

  • VICE: Full C128 emulation
  • MAME: Arcade emulation with C128 support
  • FPGA: Hardware-accurate recreations

Did You Know?

  • The C128 was the first home computer to ship with a demo program (“The Commodore 128 Personal Computer”)
  • It could address up to 16MB of RAM with bank switching
  • Some C128s were used as bulletin board system (BBS) computers well into the 1990s
  • The C128’s Z80 processor runs at 4 MHz but only when the 8502 is idle, as they share the same bus
  • Featured in the movie “The Manhattan Project” (1986)
  • Appeared in the TV show “Mr. Robot” as part of a retro computing setup
  • Referenced in the book “Ready Player Two” by Ernest Cline