PC97338VLJ datasheet(76/221 Pages) NSC

76 / 221 page

www.national.com

0 - WP is active, i.e., the FDD in the selected

drive is write protected.

1 - WP is not active, i.e., the FDD in the selected

drive is not write protected.

Bit 2 - Beginning of Track (INDEX)

This bit indicates the beginning of a track. Its value

reflects the status of the INDEX disk interface in-

put signal.

0 - INDEX is active, i.e., it is the beginning of a

track.

1 - INDEX is not active, i.e., it is not the beginning

of a track.

Bit 3 - Head Select

This bit indicates which side of the Floppy Disk

Drive (FDD) is selected by the head. Its value is

the inverse of the HDSEL disk interface output sig-

nal.

0 - HDSEL is not active, i.e., the head of the FDD

selects side 0. (Default)

1 - HDSEL is active, i.e., the head of the FDD se-

lects side 1.

Bit 4 - At Track 0 (TRK0)

This bit indicates whether or not the head of the

Floppy Disk Drive (FDD) is at track 0. Its value re-

flects the status of the TRK0 disk interface input

signal.

0 - TRK0 is active, i.e., the head of the FDD is at

track 0.

1 - TRK0 is not active, i.e., the head of the FDD is

not at track 0.

Bit 5 - Step

This bit indicates whether or not the head of the

Floppy Disk Drive (FDD) should move during a

seek operation. Its value is the inverse of the

STEP disk interface output signal.

0 - STEP is not active, i.e., the head of the FDD

moves. (Default)

1 - STEP is active (low), i.e., the head of the FDD

does not move.

Bit 6 - Second Drive Installed (DRV2)

This bit indicates whether or not a second Floppy

Disk Drive (FDD) has been installed. Its value re-

flects the status of the TRK0 disk interface input

signal.

0 - DRV2 is active, i.e., a second FDD has been

installed.

1 - DRV2 is not active, i.e., a second FDD has not

been installed.

Bit 7 - IRQ6 Pending

This bit signals the completion of the execution

phase of certain FDC commands. Its value reflects

the status of the IRQ6 pin.

0 - IRQ6 is not active.

1 - IRQ6 is active, i.e., the FDD has completed

execution of certain FDC commands.

3.3.3

Status Register B (SRB),

Offset 001

Status Register B (SRB) is a read-only diagnostic reg-

ister that is valid only in PS/2 mode.

SRB can be read at any time while PS/2 mode is ac-

tive. In PC-AT mode, all bits are in TRI-STATE during

a microprocessor read.

FIGURE 46. SRB Register Bitmap

Bit 0 - Motor 0 Status (MTR0)

This bit indicates whether motor 0 is on or off. It re-

flects the status of the MTR0 disk interface output

signal.

This bit is cleared to 0 by a hardware reset and un-

affected by a software reset.

0 - MTR0 is not active. Motor 0 is off.

1 - MTR0 is active. Motor 0 is on. (Default)

Bit 1 - Motor 1 Status (MTR1)

This bit indicates whether motor 1 is on or off. It re-

flects the status of the MTR1 disk interface output

signal.

This bit is cleared to 0 by a hardware reset and un-

affected by a software reset.

0 - MTR0 is not active. Motor 1 is off.

1 - MTR0 is active. Motor 1 is on. (Default)

Bit 2 - Write Circuitry Status (WGATE)

This bit indicates whether the write circuitry of the

selected Floppy Disk Drive (FDD) is enabled or

not. It reflects the status of the WGATE disk inter-

face output signal.

321

Reset

Required

Status Register

B (SRB)

Offset 001

WGATE

WDATA

Drive Select 0 Status

Reserved

MTR0

MTR1

RDATA

PC97338VLJ датащи(PDF) 76 Page - National Semiconductor (TI)

PC97338VLJ датащи(HTML) 76 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL