LPC47B37X datasheet(21/254 Pages) SMSC

21 / 254 page

FLOPPY DISK CONTROLLER

The Floppy Disk Controller (FDC) provides the

interface between a host microprocessor and the

floppy disk drives.

The FDC integrates the

functions of the Formatter/Controller, Digital Data

Separator, Write Precompensation and Data Rate

Selection logic for an IBM XT/AT compatible FDC.

The true CMOS 765B core guarantees 100% IBM

PC XT/AT compatibility in addition to providing

data overflow and underflow protection.

The FDC is compatible to the 82077AA using

SMSC's proprietary floppy disk controller core.

FDC Internal Registers

The Floppy Disk Controller contains eight internal

registers that facilitate the interfacing between the

host microprocessor and the disk drive. Table 2

shows the addresses required to access these

registers. Registers other than the ones shown

are not supported.

The rest of the description

assumes that the primary addresses have been

selected.

Table 2 - Status, Data and Control Registers

(Shown with base addresses of 3F0 and 370)

PRIMARY

ADDRESS

SECONDARY

ADDRESS

R/W

3F0

3F1

3F2

3F3

3F4

3F5

3F6

3F7

370

371

372

373

374

375

376

377

R/W

Status Register A (SRA)

Status Register B (SRB)

Digital Output Register (DOR)

Tape Drive Register (TDR)

Main Status Register (MSR)

Data Rate Select Register (DSR)

Data (FIFO)

Reserved

Digital Input Register (DIR)

Configuration Control Register (CCR)

Status Register A (SRA)

Address 3F0 READ ONLY

This register is read-only and monitors the state of the internal interrupt signal and several disk interface

pins in PS/2 and Model 30 modes. The SRA can be accessed at any time when in PS/2 mode. In the

PC/AT mode the data bus pins D0 - D7 are held in a high impedance state for a read of address 3F0.

PS/2 Mode

INT

PENDING

nDRV2

STEP

nTRK0 HDSEL nINDX

nWP

DIR

RESET

COND.

N/A

BIT 0 DIRECTION

Active high status indicating the direction of head movement. A logic "1" indicates inward direction; a logic

"0" indicates outward direction.

LPC47B37X Datasheet(PDF) 21 Page - SMSC Corporation

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