Commodore 128

From C64-Wiki

This article is under construction and classified as "work in progress" !!!

The C128 (short for "Commodore 128", also CBM128 or C=128) is the successor and the "big brother" of the C64. It was not only developed as a home computer, but also an office computer. It is almost entirely backwards compatible with the C64 and has two processors: one MOS 6502 variant and one Z80. The Z80 processor enables it to run the CP/M operating system, as well as any CP/M software. In addition, the C128 has more free working memory, a built-in reset button, an additional numeric keypad, an assembler monitor and a higher display resolution.

The C128 has three modes:

1. BASIC 7 (available after turning on the C128)
2. BASIC 2; C64 mode (available after entering GO64 or holding down the C= key at startup)
3. CP/M+ (version 3.0; available after inserting and loading the CP/M system from disk drive)

In 1986, the C128D was introduced, which integrated the C128 and 1571 into a single case that resembled a desktop PC. The C128D also had a detachable keyboard, the only C64/128 variant to have one.

The C128 will automatically boot from drive 8 if a disk is in the drive while the computer is turned on.

In Germany, a total number of 284,300 units were sold, while about 4.5 million units have been sold worldwide.

Contents 1 Construction 1.1 Right side 1.2 Rear 1.3 Main board 2 Links

[edit] Construction

The C128 has following connectors, switches and interfaces:

[edit] Right side

1. Game port (Control port) 1; 9 pin Sub-D connector for connecting a joystick, light pen, mouse or paddles
2. Game port (Control port) 2; 9 pin Sub-D connector for connecting a joystick, light pen, mouse or paddles
3. Reset switch
4. Power on/off switch
5. Power connector (Power; 5 pin angular) for the power supply)

[edit] Rear

1. Main memory expansion (Expansion port; 44 pin; I/O) for connecting cartridges
2. Cassette/Datasette port (Cassette port); 12 pin; I/O) for connecting a Datasette drive
3. Serial bus or Serial interface (IEEE-488; 6 pin; I/O) for connecting disk drives or a printer
4. Audio/Video connector (8 pin; I/O) for connecting a monitor/TV in 40 char mode,
5. Antenna connector for connecting to TVs in 40 char mode (left of it: L-H for channel adjustment (optional)).
6. RGBI connector (9 pin, output only) for connecting an RGB or monochrome monitor in 80 char mode.
7. Userport (RS-232 or Centronics; 24 pin; I/O), which can be used by the C128 for connecting a modem or printer interface

[edit] Main board

• Processor: HMOSII 8502 with about 1.02 or 2.04 MHz memory clock, Z80B processor 4 MHz version with 2.04 MHz clocked
• Memory: 128 KByte RAM on two 64 KByte Chips (expandable internal on max. 256 KByte, external max. 640 KByte), from this are 38,911 or 122,365 Bytes free for use under BASIC
  • Picture frequency memory VDC-8563 (16 KByte video RAM)
  • Color memory 8564 (4×2 KByte)

• ROM: 64 KByte, split:
  • C64 mode (16 KByte), Commodore BASIC V2.0 (8 KByte) and KERNAL (8 KByte)
  • C128 mode (64 KByte), Commodore BASIC V7.0 (48 KByte in 2×16 KByte Chips), KERNAL (16 KByte) and C128 BIOS (16 KByte)
  • CP/M BIOS (4 KByte)
  • Special character set NMOS-ROM (8 KByte)
  • Free connector for 32 KByte ROM (e.g. EPROM or additional character ROM)
• Video:
  • The VIC-II or VIC-8564 for the 40 character mode has the ability for 25 (rows) × 40 (columns) characters (singlecolor and multicolor) in text mode (either big letters/graphic signs or big/small letters) or in graphic mode (HiRes) 320×200 pixel in 16 colors, 16 frame colors and 16 background colors or Multicolor mode (4 colors) 160×200 pixel, as well as 8 Sprites (singlecolor or multicolor, 24×21) displaying.
  • VDC-8563 for 80 character mode 25 (rows) × 80 (columns) with 16 colors, 8 character attributes, 16 frame colors and 16 background colors in text mode (either big letters/graphic signs or big/small letters) or in graphic mode (HiRes) 640×200 pixel singlecolor or 640×400 interlaced

• Audio: SID 6581/8580
  • Sound generator for three voices, 0-4 kHz
  • 4 wave forms per generator (Sine, Triangle, Pulse, Noise)
  • 3 amplitude modulators, 48dB
  • 3 ADSR envelope generators
  • Oscillator sync
  • Ring modulation
  • Programmable filters (low, band-pass, high-pass or notch filter)
  • Random generator
  • 2 connections for potentiometers
  • Audio inputs
• Keyboard: 92 keys (QWERTY/QWERTZ), which are multiple reserved, with numeric keypad, German keyboard with DIN mode and

<ESCape>, <TAB>, <ALT>, <CAPS LOCK/ASCII+DIN>, <HELP>, <Line Feed>, <40/80-DISPLAY>, <NO SCROLL>, the Function buttons are predefined

• Miscellaneous: 2 CIA-6526 for the I/O control (Input/Output), IC for memory management MMU-8722

[edit] Links

Wikipedia: Commodore_128

• Blogger Joe Kirps and C128 designer Bil Herd talk about how the C128 came to be
• Commodore 128 Systems Guide
• VICE: Versatile Commodore Emulator
• Commodore128 Alive!