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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.〔"The FD1771 is a single-chip floppy disk formatter/controller that interfaces with most available disk drives and virtually all types of computers."〕〔 The FD1771 was announced on July 19, 1976, and sold for $60 each in lots of 100.〕 == Derivatives == The FD1771 was succeeded by many derivatives that were mostly software-compatible: *The FD1781 was designed for double density, but required external modulation and demodulation circuitry, so it could support MFM, M2FM, or other double-density encodings.〔 The FD1781 was announced on September 21, 1977. Supported Dual density; accommodates MFM, M2FM.〕 *The FD1791-FD1797 series added internal support for double density (MFM) modulation, compatible with the IBM System/34 disk format. They required an external data separator.〔(FD 179X-02 datasheet )〕 *The WD1761-WD1767 series were versions of the FD179x series rated for a maximum clock frequency of 1 MHz, resulting in a data rate limit of 125 kbit/s for single density and 250 kbit/s for double density, thus preventing them from being used for 8-in (200 mm) floppy drives or the later "high-density" or 90 mm floppy drives. *The WD2791-WD2797 series added an internal data separator using an analog phase-locked loop, with some external passive components required for the VCO. They took a 1 MHz or 2 MHz clock and were intended for and drives.〔(WD279X-02 datasheet )〕 *The WD1770, WD1772, and WD1773 added an internal digital data separator and write precompensator, eliminating the need for external passive components but raising the clock rate requirement to 8 MHz. They supported double density, despite the apparent regression of the part number, and were packaged in 28-pin DIP packages.〔(WD177X-00 datasheet images )〕 * *The WD1772PH02-02 was a version of the chip that Atari fitted to the Atari STE which supported high density (500 kbit/s) operation. After production at WD could not be sustained, Atari decided to licence the design and modify it to get high density and extra density (1MBit/s) operation. The chip was codenamed "Ajax", had the number C302096 and was produced by Toshiba. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Western Digital FD1771」の詳細全文を読む スポンサード リンク
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