PC87309 datasheet(77/192 Pages) NSC

77 / 192 page

The Floppy Disk Controller (FDC) (Logical Device 0)

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Result Phase

Upon terminating the execution phase of the WRITE DATA

command, the controller asserts IRQ6, indicating the begin-

ning of the result phase. The microprocessor must then

read the result bytes from the FIFO.

The values that are read back in the result bytes are shown

in TABLE 3-17 on page 66. If an error occurs, the result

bytes indicate the sector read when the error occurred.

3.7.25

The WRITE DELETED DATA Command

The WRITE DELETED DATA command receives data from

the host and writes logical sectors containing a deleted data

Address Mark (AM) to the selected drive.

This command is identical to the WRITE DATA command,

except that a deleted data AM, instead of a normal data AM,

is written to the data field.

Command Phase

See Section 3.7.10 on page 64 and Section 3.7.24 on page

76 for a description of these bytes.

Execution Phase

Data is transferred from the system to the controller in DMA

or non-DMA modes, and written to the disk. See Section

3.4.2 on page 45 for a description of these data transfer

modes.

Result Phase.

Upon terminating the execution phase of the WRITE DATA

command, the controller asserts IRQ6, indicating the begin-

ning of the result phase. The microprocessor must then

read the result bytes from the FIFO.

The values that are read back in the result bytes are shown

in TABLE 3-17 on page 66. If an error occurs, the result

bytes indicate the sector read when the error occurred.

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

001001

IPS

XXXX

DS1

DS0

Track Number

Head Number

Sector Number

Bytes-Per-Sector Code

End of Track (EOT) Sector Number

Bytes Between Sectors - Gap 3

Data Length (Obsolete)

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

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