CS5530A datasheet(66/259 Pages) NSC

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Functional Description (Continued)

Table 3-20. Floppy Disk Idle Timer and Trap Related Registers

Bit

Description

F0 Index 81h

Power Management Enable Register 2 (R/W)

Reset Value = 00h

Floppy Disk Idle Timer Enable: Load timer from Floppy Disk Idle Timer Count Register (F0 Index 9Ah) and generate an

SMI when the timer expires. 0 = Disable; 1 = Enable.

If an access occurs in the address ranges (listed below) the timer is reloaded with the programmed count.

Primary floppy disk: I/O Port 3F2h, 3F4h, 3F5h, and 3F7

Secondary floppy disk: I/O Port 372h, 373h, 375h, and 377h

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status is reported at F0 Index 85h/F5h[1].

F0 Index 82h

Power Management Enable Register 3 (R/W)

Reset Value = 00h

Floppy Disk Trap: 0 = Disable; 1 = Enable.

If this bit is enabled and an access occurs in the address ranges (listed below) an SMI is generated.

Primary floppy disk: I/O Port 3F2h, 3F4h, 3F5h, or 3F7

Secondary floppy disk: I/O Port 372h, 373h, 375h, or 377h

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status is reported at F0 Index 86h/F6h[1].

F0 Index 93h

Miscellaneous Device Control Register (R/W)

Reset Value = 00h

Floppy Drive Port Select: All system resources used to power manage the floppy drive use the primary or secondary FDC

addresses for decode. 0 = Primary; 1 = Primary and Secondary.

F0 Index 9Ah-9Bh

Floppy Disk Idle Timer Count Register (R/W)

Reset Value = 0000h

15:0

Floppy Disk Idle Timer Count: The idle timer loaded from this register is used to determine when the floppy disk drive is

not in use so that it can be powered down. The 16-bit value programmed here represents the period of floppy disk drive

inactivity after which the system is alerted via an SMI. The timer is automatically reloaded with the count value whenever an

access occurs to any of I/O Ports 3F2h, 3F4h, 3F5h, and 3F7h (primary) or 372h, 374h, 375h, and 377h (secondary). The

timer uses a 1 second timebase.

To enable this timer set F0 Index 81h[1] = 1.

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status is reported at F0 Index 85h/F5h[1].

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