General Description

The GM82C765B is a CMOS LSI device which interfaces a host microprocessor to the floppy disk drive. It integrates the function of the Formatter/Controller, Data Separator. Write Precompensation, Data rate selection, Clock Generation, High Current Output Drivers, and TTL compatible Schmitt Trigger Receivers. The GM82C765B consists of a microprocessor interface, a microsequencer and a disk drive interface.

Features

* IBM PC compatible format (single and double density)

– Floppy disk control and operations on chip

– In PC AT mode, provides required signal qualification DMA channel

– BIOS compatible and dual speed Spindle Drive support

* Integrates Formatter/Controller/Data Separation, Write Precompensation, Data rate Selection, Clock Generation, and drive interface Drivers and Receivers into one chip

* Multisector and Multitrack transfer capability.

* Direct Floppy Disk Drive interface with no buffers needed

– 48mA sink output drivers

– Schmitt trigger Line Receivers

* Enhanced Host Interface:

– Supports 12MHz, 286 u-processor

– Capable of driving 20 LSTTL Load

* Address mark detection circuitary internal to Floppy Disk Controller

* On chip Clock Generation Two TTL Clock Inputs for 40-DIP

* Two XTAL oscillator circuits for 44-Quad, PLCC

* User programmable Track Stepping Rate and Head load/unload time

* Drivers up to four Floppy or micro Floppy Disk Drives

* Data transfer DMA or non-DMA mode

* Parallel seek operations on up to four Drives

* Internal power up reset circuitry

* READ/WRITE access compatible register with 8 or 12MHz 286 microprocessor with 0 wait states.

* DMA timing corrected.

* LOW POWER CMOS, +5V SUPPLY