Commodore 128

Commodore released the C-128 in 1985 as a dual-CPU, triple-mode home computer with 128K RAM and compatibility with both C64 software and CP/M applications, positioning it as a high-end upgrade path for existing users.

The C-128 was designed to serve as a bridge between the wildly successful C64 and the business computing world, offering three distinct operating modes: native 128 mode, C64 compatibility mode, and CP/M mode¹²¹³¹⁴. This tripartite architecture, described contemporaneously as "drei verschiedene Betriebsarten", allowed users to run legacy C64 software, access enhanced capabilities via Commodore Basic 7.0, or execute CP/M 3.0 applications¹³¹⁴⁵⁹. The machine’s dual-processor configuration centered on an 8502 microprocessor, compatible with the 6502 family and switchable between 1 MHz and 2 MHz operation¹³¹⁴. In C64 mode, the system reverted to using a 6510A CPU running at 1.02 MHz¹³¹⁴.

Memory architecture was a key differentiator. The base configuration included 128K of RAM and 48K of ROM¹³¹⁴, with the ability to expand memory by 512K using external modules, bringing total capacity to 640K¹⁰¹¹. The 1750 RAM Expansion Unit (REU) not only enabled this expansion but also supported data transfer rates up to 1 megabyte per second, a notable performance claim for the era¹⁰. Video memory was expandable to 64K, required for certain software such as the desktop publishing application NEWS MAKER 128³.

Display output supported both 40- and 80-column text modes, with pixel resolutions of 320 × 200 and 640 × 200 respectively in 128 mode¹³¹⁴. The system retained the C64’s 16-color palette¹³¹⁴, and could drive either RGBI or composite monitors, notably the Commodore 1902¹⁰. However, some applications required an RGB monitor and a mouse, indicating a push toward more sophisticated graphical environments³.

Storage was initially handled via external drives such as the 1571 and 1581, with the original "Flat 128" model integrating CPU and keyboard in a single case and relying entirely on peripherals². The later 128D revision introduced a built-in 1571 drive and a detached keyboard, adopting what one Danish publication called "Commodores slanke PC look"⁵⁹. The 128D was marketed as the "NEW C-128D" with packages explicitly listing the internal disk drive as a feature⁶.

The keyboard, praised in period reviews as "elegant" and well-styled, included a numeric keypad, a feature absent on the C64 and increasingly expected in professional machines⁵⁹¹². I/O capabilities included a "schnellen seriellen Bus" (fast serial bus) for disk and printer connectivity, along with support for modems like the 1670 and C-1660¹³¹⁴⁶. Mouse support was provided through the C-1350 and C-1351 models, and third-party graphics interfaces such as the XETEC Super Graphix series were compatible⁶.

Software support emphasized backward and forward compatibility. All C64 software could run in C64 mode, and the catalog assured users of "100 per cent compatible" operation¹¹². Native C-128 software, including titles like COMPUTEI'S FIRST BOOK OF THE COMMODORE 128, was explicitly designed for 128 mode and would not function on earlier hardware¹. CP/M mode enabled use of business software such as WordStar, dBase II, and The Perfect Series¹⁰, though a documented flaw existed: 10 of the 96 characters in the CP/M Plus printing character set were incorrect, causing compatibility issues with standard CP/M print routines⁸. The editorial response suggested workarounds involving ASCII output and printer mode settings, indicating a layer of technical friction⁸.

At launch, the C-128 was priced at £199.95 in the UK⁴, and was expected to be available by autumn 1985¹². Bundled packages such as the "COMMODORE 128 COMPENDIUM PACK" included the C2N datasette, Music Maker Keyboard, and games like Spirit of the Stones, Jack Attack, and International Soccer⁴. Other supported software included GEOS CBM 64/128 and Superbase 128⁴.

Despite its ambitious scope, the C-128 inherited complexities that undermined its usability. The need to manage multiple character sets (PETSCII vs. ASCII), inconsistent printer behavior in CP/M mode, and the requirement for specific hardware upgrades to run certain software reflected a machine stretched across too many use cases. Yet its engineering, particularly the switching between modes and the performance of the REU, demonstrated Commodore’s technical ambition at its peak.

Specifications

References

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