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26-3022
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This page was last updated on 09/10/2012. Total Pages: 744. Total Files: 994.
the 26-3022 Mini-Disk System was the first production release of a disk controller/drive for use with the original Color Computer.
The controller is based on the Western Digital WD1793. It features an analog data seperator circuit, infamous for its inherent unreliability and has multiple potentiometers which are used to calibrate various delay and timing features of the disk-side interface. It requires a +12 volt DC supply to operate, and is thus not compatible with a CoCo 2 or 3 unless a Multi-Pak Interface (or other source of +12V) is used or the CoCo or controller are "hacked", also contains the Disk BASIC ROM chip, and the necessary interface logic.
The disk drive is a Texas Peripherals unit encased in a silver-colored enclosure with a simple linear power supply and a 5.25" single-sided (in most cases), double-density, half-height (in most cases) floppy drive. A captive (in most cases) ribbon cable exits the drive unit, terminated in a 34-pin card-edge connector which attaches to the controller pak. The drive unit also has an AC power, power swich and power cord. Even though the drives and controllers were sold as packages, they can be interchanged almost universally. The drive is capable of accessing about 37 tracks, so a 35 track limit was imposed in Disk BASIC.
These drives are not the most robust, and many that are out there are probably in need of work. (if they work at all)
The 26-3022 controller is the only one capable of being modified (though with considerable difficulty) to allow use with high-density 3.5" floppy drives.
All subsequent controllers use the WD1773 controller chip, do not use the unreliable analog data separator, do not require +12V (so they will work with any CoCo model), and are capable of double-density operation only.