PC97307 datasheet(87/218 Pages) NSC

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5.7.1

Abbreviations Used in FDC Commands

BFR

Buffer enable bit set in the MODE command. En-

ables open-collector output buffers.

BST

Burst mode disable control bit set in MODE com-

mand. Disables burst mode for the FIFO, if the

FIFO is enabled.

DC3-0 Drive Conﬁguration for drives 3-0. Used to conﬁg-

ure a logical drive to conventional or perpendicular

mode in the PERPENDICULAR MODE command.

DENSEL

Density Select control bits set in the MODE com-

mand.

DIR

Direction control bit used in RELATIVE SEEK com-

mand to indicate step in or out.

DMA DMA mode enable bit set in the SPECIFY com-

mand.

DS1-0 Drive Select for bits 1,0 used in most commands.

Selects the logical drive.

Enable Count control bit set in the VERIFY com-

mand. When this bit is 1, SC (Sectors to read

Count) command byte is required.

EIS

Enable Implied Seeks. Set in the CONFIGURE

command.

EOT

End of Track parameter set in read, write, scan,

and VERIFY commands.

ETR

Extended Track Range set in the MODE command.

FIFO First-In First-Out buffer. Also a control bit set in the

CONFIGURE command to enable or disable the

FIFO.

FRD

FIFO Read Disable control bit set in the MODE

command

FWR FIFO Write disable control bit set in the MODE

command.

Gap 2 The length of gap 2 in the FORMAT TRACK com-

mand and the portion of it that is rewritten in the

WRITE DATA command depend on the drive

mode, i.e., perpendicular or conventional. Figure

5-20 on page 91 illustrates gap 2 graphically. For

more details, see “Bits 1,0 - Group Drive Mode

Conﬁguration (GDC)” on page 95.

Gap 3 Gap 3 is the space between sectors, excluding the

synchronization ﬁeld. It is deﬁned in the FORMAT

TRACK command. See Figure 5-20 on page 91.

GDC

Group Drive Conﬁguration for all drives. Conﬁgures

all logical drives as conventional or perpendicular.

Used in the PERPENDICULAR MODE command.

Formerly, GAP2 and WG.

Head Select control bit used in most commands.

Selects Head 0 or 1 of the disk.

IAF

Index Address Field control bit set in the MODE

command. Enables the ISO Format during the

FORMAT command.

IPS

Implied Seek enable bit set in the MODE, read,

write, and scan commands.

LOCK Lock enable bit in the LOCK command. Used to

prevent certain parameters from being affected by

a software reset.

LOW PWR

Low Power control bits set in the MODE command.

MFM Modiﬁed Frequency Modulation parameter used in

FORMAT TRACK, read, VERIFY and write com-

mands.

MFT

Motor Off Time. Now called Delay After Processing

time. This delay is set by the SPECIFY command.

MNT

Motor On Time. Now called Delay Before Process-

ing time. This delay is set by the SPECIFY com-

mand.

MSB

Most Signiﬁcant Byte controls which whether the

most or least signiﬁcant byte is read or written in

the SET TRACK command.

Multi-Track enable bit used in read, write, scan and

VERIFY commands.

Overwrite control bit set in the PERPENDICULAR

MODE command.

POLL Enable Drive Polling bit set in the CONFIGURE

command.

PRETRK

Precompensation Track Number set in the CON-

FIGURE command

PTR

Present Track number. Contains the internal 8-bit

track number or the least signiﬁcant byte of the 12-

bit track number of one of the four logical disk

drives. PTR is set in the SET TRACK command.

R255 Recalibration control bit set in MODE command.

Sets maximum number of STEP pulses during

RECALIBRATE command to 255.

RTN

Relative Track Number used in the RELATIVE

SEEK command.

Sector Count control bit used in the VERIFY com-

mand.

Skip control bit set in read and scan and VERIFY

operations.

SRT

Step Rate Time set in the SPECIFY command. De-

termines the time between STEP pulses for SEEK

and RECALIBRATE operations.

ST0-3

Result phase Status registers 3-0 that contain sta-

tus information about the execution of a command.

See Sections 5.5.1 through 5.5.4.

THRESH

FIFO threshold parameter set in the CONFIGURE

command

TMR

Timer control bit set in the MODE command. Af-

fects the timers set in the SPECIFY command.

Formerly, the Write Gate control bit. Now included

in the Group Drive mode Conﬁguration (GDC) bits

in the PERPENDICULAR MODE command.

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