MOS Technologies 8563
The MOS Technology 8563 aka VDC (for Video Display Controller) was MOS' 80-column display video chip used in the Commodore 128 home computer (the C128 also had a VIC-II for producing bitmap graphics and 40-column text, and for C64 compatibility).
Originally intended for a planned (but unreleased) UNIX-based business computer, Commodore designed the 8563 into several prototype machines, of which the C128 was the only one to be completed, industrialized, and released. The 8563 was a departure from other MOS video chip designs in that it had its own dedicated memory, and memory space, separate from system memory. In addition, yields on the chip were very low, and Commodore's official position after the release of the C128 was that the VDC was incapable of producing bitmapped graphics.
Usable bitmap modes were nevertheless discovered within a year of the C128's release; an extension to the C128's BASIC 7.0 that enabled these capabilities appeared in RUN, a magazine dedicated to Commodore 8-bit computers. This extension would later be refined into the commercially available GEOS operating system.
Although the VDC did have usable high-resolution graphics modes, it lacked hardware sprite capabilities, which limited the C128's use as a gaming platform in its own right.
Technical specifications
- 16 or 64 KB address space for screen, character and color memory (dedicated, separate from system memory)
- 640 × 200 pixel video resolution (640 × 400 in interlaced mode)
- 80 × 25, 80 × 50, 40 × 25 characters text resolution
- 16 colors
