PC97338 datasheet(103/221 Pages) NSC

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Bits 7,6 - Density Select Pin Configuration

(DENSEL)

This field can configure the polarity of the Density

Select output signal (DENSEL) as always low or

always high, as shown in Table 4-3. This allows

the user more flexibility with new drive types.

This field overrides the DENSEL polarity defined

by the DENSEL polarity bit of the Advanced Su-

perI/O Chip (ASC) configuration register de-

scribed on page 53.

00 - The DENSEL signal is always low.

01 - The DENSEL signal is always high.

10 - The DENSEL signal is undefined.

11 - The polarity of the DENSEL signal is defined

by the DENSEL Polarity bit (bit 6) of the ASC

TABLE 48. DENSEL Encoding

Execution Phase

Internal registers are written.

Result Phase

None.

3.6.8

The NSC Command

The NSC command can be used to distinguish be-

tween the FDC versions and the 82077.

Command Phase

Execution Phase

Result Phase

The result phase byte of the NSC command identifies

the

floppy

disk

controller

(FDC)

PC87338/PC97338 by returning a value of 73h.

The 82077 and DP8473 return the value 80 hex, sig-

nifying an invalid command.

Bits 3-0 of this result byte are subject to change by

NSC, and specify the version of the Floppy Disk Con-

troller (FDC).

Bit 7

Bit 6

DENSEL Pin Definition

DENSEL low

DENSEL high

undefined

Set by ASC register.

7654

3210

0001

1000

7654

3210

0111

0011

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