Commodore 128

Commodore 128
Type:	Home Computer
Producer:	Commodore
Price:	300 US$
Released:	1985
Discontinued:	1989
Processor:	MOS 8502 @ ca. 1,02 or 2,04 MHz Z80 @ 2,04 MHz
Memory:	128 KByte, upgradeable
OS:	BASIC 7.0 BASIC V2.0 Bootable from disk: CP/M
Info:	Alias C128 and CBM-128 different models C128, C128D and C128DCR Predecessor: C64

The C128 home computer (known as the Commodore 128, CBM 128, and C=128) was Commodore’s successor to the C64. It functioned as a dual home/office computer and was 99% compatible with existing C64 programs. It featured two processors: an MOS 6502 variant and a Z80. The Z80 enabled it to run the industry standard CP/M operating system and software. The C128 had more free working memory than the C64, a built-in reset button, a numeric keypad, a machine code 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, Commodore introduced another model, the C128D, which integrated the C128 and 1571 floppy disk into a single desktop case. Both models will boot automatically from floppy disk. The C128D/C128DCR also featured a detachable desktop keyboard (all other C64/C128 models had a fixed keyboard).

Worldwide, Commodore sold around 4,500,000 units, with 284,300 units sold in Germany.

Construction

The C128 has following connectors, switches and interfaces:

Right side

Commodore 128 - 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, mouse or paddles
3. Reset switch
4. Power on/off switch
5. Power connector (Power; 5 pin angular) for the power supply)

Rear

Commodore 128 - backside

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 interface or Serial Port (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

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)

Commodore 128 - Mainboard

• 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

Startscreen of Commodore 128

• 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

Function Keys

The C128/D/DCR function keys are normally:

• F1  GRAPHIC
• SHIFT +F2  DLOAD+CHR$(34)
• F3  DIRECTORY+CHR$(13) (the key RETURN  is hit)
• SHIFT +F4  SCNCLR+CHR$(13)
• F5 DSAVE+CHR$(34)
• SHIFT +F6  RUN+CHR$(13)
• F7  LIST+CHR$(13)
• F8  MONITOR+CHR$(13)

An overview or a modify of the function keys follows through the BASIC-command KEY in direct mode or in programs. After a reset or a reboot are the normally function key configuration active.

Links

Wikipedia: Commodore_128

• PDF:"Mapping the Commodore 128"
• C128 Systemguide at www.commodore.ca
• C128 Gamebase
• List of all C128 software
• "Tips and Tricks for C128"