How Many Colors Could the Commodore Plus/4 Display?

The Commodore Plus/4 computer, released in 1984, utilized the TED chip which supported a total palette of 128 colors. However, the number of colors displayed simultaneously on the screen depended on the graphics mode used. In standard high-resolution text mode, the system could display up to 16 colors at once, while multicolor mode was limited to four colors per character cell. This article explores the technical specifications of the TED chip and how these color limits impacted software and gaming on the platform.

At the heart of the Plus/4’s graphics capability was the TED (Text Editing Device) chip, model 7360. Unlike the VIC-II chip found in the popular Commodore 64, which was limited to a fixed palette of 16 colors, the TED chip offered a significantly larger range of hues and luminances. The total available palette consisted of 128 colors, derived from 16 different hues each with 8 luminance levels. This expanded palette allowed for more nuanced shading and visual variety compared to earlier 8-bit Commodore machines, even if the simultaneous display limits were similar.

The number of colors visible at any one time was dictated by the specific graphics mode selected by the software. In high-resolution mode, each 8x8 character cell could define its own foreground color while sharing a global background color. Since the system allowed for 16 color register selections, a screen could theoretically display 16 distinct colors simultaneously—one background color and 15 different foreground colors across various characters. In multicolor mode, which sacrificed horizontal resolution for larger color blocks, each character cell was restricted to four colors simultaneously: the global background, the cell background, and two additional multicolor hues.

These technical specifications defined the visual identity of the Commodore Plus/4 during its lifespan. While the 128-color palette was a marketing highlight, developers had to work within the constraints of the simultaneous color limits per character cell. This architecture influenced game design and user interface aesthetics, requiring programmers to manage color attributes carefully to avoid color clash. Ultimately, the Plus/4 offered a richer total color selection than its predecessors, even though the on-screen simultaneous count remained bound by the memory and architecture of the era.