INTRODUCTION
The 82077AA is a true single-chip floppy disk, and tape drive controller for the PC-AT and PS/2. The 82077AA, a 24 MHz crystal, a resistor package and a chip select implement a complete design. All drive control signals are fully decoded and have 40 mA drive buffers with selectable polarity. Signals returned from the drive are sent through on-chip input buffers with hysteresis for noise immunity. The integrated analog data separator needs no external compensation yet allows for a wide motor speed variation with exceptionally low soft error rates. The microprocessor interface has a 12 mA drive buffer on the data bus plus 100% hardware register compatibility for PC-AT’s and PS/2’s. The 16-byte FIFO with programmable thresholds is extremely useful in multi-master systems (PS/2, EISA) or systems with a large amount of bus latency.

■ Single-Chip Floppy Disk Solution
   — 100% PC AT* Compatible
   — 100% PS/2* Compatible
   — 100% PS/2 Model 30 Compatible
   — Integrated Drive and Data Bus Buffers
■ Integrated Analog Data Separator
   — 250 Kbits/sec
   — 300 Kbits/sec
   — 500 Kbits/sec
   — 1 Mbits/sec
■ High Speed Processor Interface
■ Perpendicular Recording Support
■ Integrated Tape Drive Support
■ 12 mA Host Interface Drivers, 40 mA Disk Drivers
■ Four Fully Decoded Drive Select and Motor Signals
■ Programmable Write Precompensation Delays
■ Addresses 256 Tracks Directly, Supports Unlimited Tracks
■ 16 Byte FIFO
■ 68-Pin PLCC
   (See Packaging Spec., Order Ý240800, Package Type N)