Commodore 128

"Equipped with 2 CPUs and capable of running multiple Operating Systems"

Manufactured between 1985 and 1989, the Commodore 128 was Commodore's last 8-bit home computer. Based on its 2 CPUs, C128 is capable of running Commodore Basic and GEOS through the MOS 8502, plus CP/M through the Zilog Z80. Note, that there are also 2 desktop versions of C128 with a built-in 5.25'' 1571 Floppy Disk Drive and a 93-key QWERTY detachable keyboard.

C128 was initially priced at $299 ($850 in today's money), and the later C128D at $499.95 ($1,420 in today's money)
Overall, the C128 sold about 4 million units (estimation) -The original C128 sold about 2.5 million units, and 1.5 million the two desktop models (C128D and C128DCR)

C128 AT A GLANCE

The C128 was released in July 1985 in the United Kingdom and in November 1985 in North America. Key hardware engineers include Bil Herd, Dave Haynie, and Frank Palaia.

There are three different C128 models, these are their common features:

All C128s are fully compatible with C64
Two CPUs (MOS 8502 CPU running at 2 Mhz & Zilog Z80 CPU running at 4 Mhz)
128 KB of RAM (2x64 KB banks and up to 512 KB REU expansion RAM)
72 KB ROM
16 colors palette (RGB) and up to 640 x 200 px (non-interlaced)
Commodore BASIC 7.0 replacing the C64's Commodore BASIC 2.0
CP/M operating system through Z80 CPU
A software library of thousands of titles, but only a few exclusives for C128

Variants / Additional Features of the C128 Desktop Models (C128D & C128DCR)

C128D These are the additional features of the two C128 desktop models:

□ C128D (Sold in Europe -resembling the Amiga 1000)

Plastic case with a carrying handle and a keyboard dock
Cooling fan built-in
16 KB VDC video RAM (8563 VDC chip)
Built-in 5.25'' Floppy Disk Drive (1571) 360k capable of reading GCR and MFM formats (Double Sided/Double Density) with a 6502 co-processor for the drive
93-key QWERTY Detachable Keyboard
Fully compatible with C64 and C128

□ C128DCR (Mainly sold in the US)

Metallic case without cooling fan, carrying handle, and keyboard dock
Metalic joystick ports and Torx screws instead of Philips screws
New ROMs (1986 ROMs) that address some bugs of the previous 128D
64 KB VDC video RAM (8568 VDC chip)
MOS 8580 SID (DCR) sound chip
Built-in 5.25'' Floppy Disk Drive (1571) 360k capable of reading GCR and MFM formats (Double Sided/Double Density) with a 6502 co-processor for the drive
93-key QWERTY Detachable Keyboard
Fully compatible with C64, C128, and C128D

Operating System

C128DCR from collection.. The Commodore 128 can operate in different modes but without being able to perform multitasking operations. The computer can boot either in Commodore Basic 7.0 or CP/M.

Commodore Basic 7.0 allows running classic C64/C128 applications
C128 can run CP/M applications and it was shipped with CP/M 3.0
C128 can run the mouse-driven GEOS (There is an enhanced GEOS version for the Commodore 128) -More about GEOS

Notes:

Commodore DOS is accessed through BASIC
Commodore DOS is built into the ROM of Commodore disk drives

Boot Process Using the 2 CPUs

During the C128 boot process, the Z80 CPU executes a small loader ROM in advance to check if a CP/M disk is inside the disk drive. If there is NO disk, then the 8502 CPU takes control of the boot process and the C128 starts in native mode.

Starting in C64 Mode

The C128 is almost perfectly compatible with Commodore 64. The C128 can start in C64 mode in three ways:

(1) Holding down the 'COMMODORE LOGO' key when booting

(2) Typing the GO 64 command

(3) Booting directly from a C64 cartridge

Software Library

There is a vast software library available of nearly 10,000 C64 commercial titles
There are a few dedicated C128 business apps (Superscript 128, Superbase 128, etc.)
Thousands of CP/M applications (word processors, graphics, sound, business applications) are available through the use of Zilog Z80
GEOS applications are also available

Video Games

Many thousands of video games (C64 mode)
About 50 dedicated C128 video games

Colors & Graphic Modes

C64/C128 Color Palette C128 offers some improvements compared with C64:

Compatible with all the original C64 modes
16 RGB colors
A dedicated graphics chip called Video Display Controller (VDC) provides 80-column color video output (CGA-compatible display)
16KB VDC video RAM for C128 and C128D
64 KB VDC video RAM for C128DCR

Video Modes:

320 x 200 (16-color palette)
640 X 200 (16-color palette)
640 x 400 (interlaced)
40 x 25 columns (Text mode 1)
80 x 25 columns (Text mode 2)

Sound Capabilities

The sound of the C128 was the same as the C64, which means fantastic sound capabilities for its time via the incredible SID synthesizer chip.

MOS 6581 SID or MOS 8580 SID (DCR) chip
3 voices, ADSR-controllable
Waveforms include triangle, sawtooth, variable pulse, noise, and combined modes

I/O Ports

These are the basic ports of C128s.

On all C128s:

2 Joystick/Mouse ports (compatible with classic 9-pin joysticks)
CBM Serial port (Round female DIN)
CBM Datasette port
User port (parallel programmable)
Monitor port
RF Audio/Video port
C64 expansion port

On Desktop Models:

Keyboard port

Expansions & Upgrades

There are a lot of decent upgrades for the C128, these are some essential ones:

VIDEO CABLES

Commodore 128 RGBI 40/80 Columns 16 Color SCART Cable (Connecting C128 to any modern TV via SCART)
C128 Upscaler VGA monitor video converter
RCA Video S-Video Stereo Cable

STORAGE UPGRADES

SD2IEC 1541 Disk Drive Emulator (SD Card Reader)
Kung Fu Flash Cartridge (SD Card)
Pi1541 1541 Floppy Disk Drive Emulator (real-time and cycle-exact) that runs on a Raspberry Pi (SD Card Reader)
Sidekick64 (Kernal/SID/FM/Freezer/RAM)
Fast-Loader Cartridge
TeensyROM Cartridge for Commodore 64/128 offering MIDI, Fastload, Emulation, and Network

RAM UPGRADES

C1750 512K RAM Expander
Extender Card for memory expansion port
NeoRAM Remix 2MB expansion for Commodore 64/128
RAD Expansion for Commodore 64/128 -RAM expansion using a Pi Zero 2

MISCELLANEOUS UPGRADES/ADD-ONS

C64/C128 StrikeLink WiFi modem
1351 MOUSE FOR COMMODORE 64/128 (For GEOS)
Diagnostic Cartridge for Commodore C64/C128

■ Commodore 128 Computers

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