WD1772
The WD1772 (Western Digital 1772) is the chip used to control and drive the floppy drive in the ST range of computers, produced between 1985 and 1993. It was preceded by the WD1770, and was replaced for 1.44MB high density support by the AJAX controller in the Falcon 030, TT and Mega STE - the plain WD1772 continued to be used for standard double density drives across the rest of the range throughout production.
Modification
- No Western Digital documentation describes any WD1772 revision, including "02-02", as officially supporting overclocked 16MHz/high-density operation - the "02-02 can be overclocked" claim is unsourced and does not survive testing. In practice, any WD1772 or VL1772 chip can typically run at 16MHz for short bursts regardless of revision marking, but none should be assumed reliable for sustained use - see WD1772 Floppy Disk Controller for the testing behind this. The only chip actually designed and documented for continuous 16MHz operation is AJAX, used in the Falcon 030, TT and Mega STE.
Programming information
In addition to used called through standard operating system calls, the WD1772 could be programmed to achieve such things as reading or writing customised disk formats, or turning the floppy access light off and on in time to music.
- WD177x Data sheets
- Programming guide for WD177x by David Gahris
- Consolidated WD1772 reference - registers, commands, formats, and the 16MHz reliability testing above, cross-checked against Hatari, EmuTOS and three source datasheets