PC87310 datasheet(28/52 Pages) NSC

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40 Functional Description (Continued)

SOFTWARE POLLING

If the non-DMA mode is selected and interrupts are not suitable the mP can poll the Main Status Register during the Execution

Phase to determine when a byte is ready to be transferred In the non-DMA mode bit 7 of the Main Status Register reflects the

state of the interrupt pin Otherwise the data transfer is similar to the Interrupt Mode described above

446 Command Description Table

See Section 447 for a detailed description of each command

Note Mnemonic Definitions

DRn e

Drive to Select (encoded)

ETR e

Extended Track Range

HD e

Head Number

IAF e

Index Address Field

IPS e

Implied Seek (In individual commands this bit is a don’t care unless the IPS bit in the mode command is set)

LW PR e

Low Power Mode

MFM e

Data Encoding Scheme

MSB e

Selects whether the most significant or least significant byte of the track is read 1 e MSB

MSN PTN e

Most Significant Nibble Present Track Number

MT e

Multi-Track

PU e

Enables Charge Pump PUMP signal to be output on the PUMPPREN pin

RG e

Enables the Read Gate Input on the DSKCHG pin for the Data Separator (Write e 1)

R W e

Selects whether the track is written or read (Read e 0)

SK e

Skip Sector

TMR e

MotorHead Timer Mode

WLD e

Wildcard in Scan

X e

DON’T CARE

READ DATA

From specified sectors in logical order

on a track (optional Implied Seek)

Command Phase

MT MFM SK

IPS

HD DR1 DR0

Track Number

Drive Head Number

Sector Number

Number of Bytes per Sector

End of Track Sector Number

Intersector Gap Length

Data Length

Note 1

Result Phase

Status Register 0

Status Register 1

Status Register 2

Track Number

Head Number

Sector Number

BytesSector

READ ID

From the first address field that is

found

Command Phase

MFM

001010

HD DR1 DR0

Result Phase

Status Register 0

Status Register 1

Status Register 2

Track Number

Head Number

Sector Number

BytesSector

FORMAT A TRACK

Write header and data patterns to the

specified track

Command Phase

MFM

001101

HD DR1 DR0

Number of Bytes per Sector

Number of Sectors per Track

Intersector Gap Length

Data Pattern

Result Phase

Status Register 0

Status Register 1

Status Register 2

Track Number

Head Number

Sector Number

BytesSector

PC87310 Datasheet(PDF) 28 Page - National Semiconductor (TI)

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