PC87372 datasheet(110/144 Pages) NSC

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Revision 1.2

9.0

Legacy Functional Blocks

This chapter briefly describes the following blocks, which provide legacy device functions:

Floppy Disk Controller (FDC)

Parallel Port (PP)

Serial Port (SP)

Keyboard and Mouse Controller (KBC)

For details on the general implementation of each legacy block, see the SuperI/O Legacy Functional Blocks datasheet.

The register maps in this chapter use the following abbreviations for Type:

R/W

= Read/Write.

= Read from register (write to the same address is to a different register).

= Write (see above).

= Read Only.

= Write Only. Reading from the bit returns 0.

R/W1C = Read/Write 1 to Clear. Writing 1 to a bit clears it to 0. Writing 0 has no effect.

R/W1S = Read/Write 1 to Set. Writing 1 to a bit sets its value to 1. Writing 0 has no effect.

9.1

FLOPPY DISK CONTROLLER (FDC)

9.1.1

General Description

The generic FDC is a standard FDC with a digital data separator; it is software compatible with the

µDP8473 and N82077.

The PC87372 FDC supports 14 of the 17 standard FDC signals described in the generic Floppy Disk Controller (FDC) chap-

ter, including:

• FDC supportS FM and MFM modes. To select either mode, set bit 6 of the first command byte when writing to/reading

from a diskette, where:

— 0 = FM mode

— 1 = MFM mode

• A logic 1 is returned during LPC I/O read cycles by all register bits, reflecting the state of floating (TRI-STATE) FDC pins.

Exceptions to standard FDC are:

• Automatic media sense using MSEN0 and MSEN1 signals is not supported.

• DRATE1 is not supported.

• DR1 is not supported.

• MTR1 is not supported.

Table 41 lists the FDC functional block registers. All registers are VDD3 powered.

Table 41. FDC Register Map

Offset1

Mnemonic

Type

00h

SRA

Status A

01h

SRB

Status B

02h

DOR

Digital Output

R/W

03h

TDR

Tape Drive

R/W

04h

MSR

Main Status

DSR

Data Rate Select

05h

FIFO

Data (FIFO)

R/W

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