PC87307 datasheet(73/218 Pages) NSC

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The Digital Floppy Disk Controller (FDC) (Logical Device 3)

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Bit 4- Motor Enable 0

If four drives are supported (bit 7 of the SuperI/O FDC

Configuration register at index F0h is 1), this bit may

control the motor output signal for drive 0, depending on

the remaining bits of this register. See Table 5-2.

If two drives are supported (bit 7 of the SuperI/O FDC

Configuration register at index F0h is 0), this bit controls

the motor output signal for drive 0.

0 - The motor signal for drive 0 is not active.

1 - The motor signal for drive 0 is active.

Bit 5 - Motor Enable 1

If four drives are supported (bit 7 of the SuperI/O FDC

Configuration register at index F0h is 1), this bit may

control the motor output signal for drive 0, depending on

the remaining bits of this register. See Table 5-2.

If two drives are supported (bit 7 of the SuperI/O FDC

Configuration register at index F0h is 0), this bit controls

the motor output signal for drive 1.

0 - The motor signal for drive 1 is not active.

1 - The motor signal for drive 1 is active.

Bit 6 - Motor Enable 2

If drives 2 and 0 are exchanged (see logical drive ex-

change bits 3,2 of TDR on page 74), or if four drives are

supported (bit 7 of the SuperI/O FDC Configuration reg-

ister at index F0h is 1), this bit controls the motor output

signal for drive 2. See Table 5-2.

0 - The motor signal for drive 2 is not active.

1 - The motor signal for drive 2 is active.

Bit 7 - Motor Enable 3

If four drives are supported (bit 7 of the SuperI/O FDC

Configuration register at index F0h is 1), this bit may

control the motor output signal for drive 3, depending on

the remaining bits of this register. See Table 5-2.

0 - The motor signal for drive 3 is not active.

1 - The motor signal for drive 3 is active.

5.3.4

Tape Drive Register (TDR), Offset 03h

The TDR register is a read/write register that acts as the

Floppy Disk Controller’s (FDC) media and drive type regis-

ter.

The TDR functions differently, depending on the mode set

by bit 6 the SuperI/O FDC Configuration register at index

F0h. See “Bit 6 - TDR Register Mode” on page 37.

AT Compatible TDR Mode

In this mode, the TDR assigns a drive number to the tape

drive support mode of the data separator. All other logical

drives can be assigned as floppy drive support. Bits 7-2 are

in TRI-STATE during read operations.

Enhanced TDR Mode

In this mode, all the bits of the TDR define operations with

PS/2 floppy disk drives.

FIGURE 5-8. TDR Register Bitmap, AT Compatible

TDR Mode

FIGURE 5-9. TDR Register Bitmap, Enhanced TDR

Mode

76543210

Reset

Required

Tape Drive

Offset 03h

Tape Drive Select 1,0

AT Compatible TDR Mode

TRI-STATE During Read Operations

Not Used

76543210

Reset

Required

Tape Drive

Offset 03h

High Density

Extra Density

Tape Drive Select 1,0

Logical Drive Exchange

Enhanced TDR Mode

Drive ID1 Information

Drive ID0 Information

TABLE 5-4. TDR Bit Utilization and Reset Values in Different Drive Modes

TDR Mode

Bit 6 of SuperI/O

FDC Conﬁguration

Bits of TDR

Extra

Density

High

Density

Drive ID1 Drive ID0

Logical Drive

Exchange

Drive Select

7654

AT Compatible

Not used. Floated in TRI-STATE during read operations.

Enhanced

Not Reset Not Reset

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