Western Digital FD1771

The FD1771 is the first in a line of floppy disk controllers produced by Western Digital. It uses single density (FM) modulation and supports the IBM 3740 disk format. It is packaged in a 40-pin DIP.
Derivatives.
The FD1771 was succeeded by many derivatives that were mostly software-compatible:
Compatible chips.
Many compatible chips were available from other vendors:
These families were used in many microcomputers and home computers including the Radio Shack TRS-80, Acorn Electron, BBC Master, Atari ST, Acorn Archimedes and the SAM Coupé, as well as the +D and DISCiPLE disk interfaces for the Sinclair ZX Spectrum, the Commodore 157x/1581 for the Commodore 64 and the Atari XF551 for the Atari XL/XE.