PC8374L datasheet(192/239 Pages) NSC

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Revision1.1

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 Port1 and 2 (SP1 and SP2)

● 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.

● R

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

● W

= Write (see above).

● RO

= Read-only.

● WO

= 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 PC8374L 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.

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PC8374L Datasheet(PDF) 192 Page - National Semiconductor (TI)

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