PC87307 datasheet(99/218 Pages) NSC

99 / 218 page

www.national.com

TABLE 5-19. SK Effect on READ DELETED DATA

Command

Result Phase

See Table 5-18 for the state of the result bytes when the

command terminates normally.

5.7.12

The READ ID Command

The READ ID command finds the next available address

field and returns the ID bytes (track number, head number,

sector number, bytes-per-sector code) to the microproces-

sor in the result phase.

The controller reads the first ID Field header bytes it can

find and reports these bytes to the system in the result

bytes.

Command Phase

After the last command phase byte is written, the controller

waits the Delay Before Processing time (see Table 5-25 on

page 106) for the selected drive. During this time, the drive

motor must be turned on by enabling the appropriate drive

and motor select disk interface output signals via the bits of

the Digital Output Register (DOR). See “Digital Output Reg-

ister (DOR), Offset 02h” on page 71.

Skip

Control

(SK)

Data

Type

Sector

Read?

Control

Mark Bit 6

of ST2

Result

Normal

No More

Sectors Read

Deleted

Normal

Termination

Normal

Sector Skipped

Deleted

Normal

Termination

76543210

Result Phase Status Register 0 (ST0)

Result Phase Status Register 1 (ST1)

Result Phase Status Register 2 (ST2)

Track Number

Head Number

Sector Number

Bytes-Per-Sector Code

76543210

MFM

001010

XXXXX

DS1

DS0

First Command Phase Byte, Opcode

See “Bit 6 - Modified Frequency Modulation (MFM)” on

page 90.

Second Command Phase Byte

See “Second Command Phase Byte” on page 90 for a

description of the Drive Select (DS1,0) and Head Select

(HD) bits.

Execution Phase

There is no data transfer during the execution phase of this

command. An interrupt is generated when the execution

phase is completed.

The READ ID command does not perform an implied seek.

After waiting the Delay Before Processing time, the control-

ler starts the data separator and waits for the data separator

to find the address field of the next sector. If an error condi-

tion occurs, the Interrupt Code (IC) bits in ST0 are set to ab-

normal termination (01), and the controller enters the result

phase.

Possible errors are:

• The microprocessor aborted the command by writing to

the FIFO.

If there is no disk in the drive, the controller gets stuck.

The microprocessor must then write a byte to the FIFO

to advance the controller to the result phase.

• Two pulses of the INDEX signal were detected since the

search began, and no Address Mark (AM) was found.

When the Address Mark (AM) is not found, the Missing

Address Mark bit (bit 0) is set in ST1. Section 5.5.2 on

page 81 describes the bits of ST1.

Result Phase

76543210

Result Phase Status Register 0 (ST0)

Result Phase Status Register 1 (ST1)

Result Phase Status Register 2 (ST2)

Track Number

Head Number

Sector Number

Bytes-Per-Sector Code

PC87307 Folha de dados(PDF) 99 Page - National Semiconductor (TI)

PC87307 Folha de dados(HTML) 99 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

Folha de dados Download

Ligação URL