PC97338VLJ datasheet(118/221 Pages) NSC

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3.6.22 The VERIFY Command

The VERIFY command verifies the contents of data

and/or address fields after they have been formatted

or written.

VERIFY reads logical sectors containing a normal

data Address Mark (AM) from the selected drive, with-

out transferring the data to the host.

The TC signal cannot terminate this command since

no data is transferred. Instead, VERIFY simulates a

TC signal by setting the Enable Count (EC) bit to1. In

this case, VERIFY terminates when the number of

sectors read equals the number of sectors to read,

i.e., Sectors to read Count (SC). If SC = 0 then 256

sectors will be verified.

When EC is 0, VERIFY ends when the End of the

Track (EOT) sector number equals the number of the

sector checked. In this case, the ninth command

phase byte is not needed and should be set to FF

(hex).

Table 61 shows how different values for the VERIFY

parameters affect termination.

Command Phase

First Command Phase Byte

See READ DATA command for a description of

these bits starting on page 105.

Second Command Phase Byte

Bits 2-0 - Drive Select (DS1,0) and Head (HD)

Select

See the description of the Drive Select bits

(DS1,0) and the Head (HD) select bit in the READ

DATA command, starting on page 106.

Bit 7 - Enable Count Control (EC)

This bit controls whether the End of Track sector

number or the Sectors to read Count (SC) triggers

termination of the VERIFY command.

See also, Table 61.

0 - Terminate VERIFY when the number of the

last sector read equals the End of Track (EOT)

sector number.

The ninth command phase byte, i.e., Sectors

to read Count (SC), is not needed and should

be set to FF (hex).

1 - Terminate VERIFY when number of sectors

read equals the number of sectors to read,

i.e., Sectors to read Count (SC).

Third through Eighth Command Phase Bytes

See “The READ DATA Command” on page 105.

Always set the End of Track (EOT) sector number

to the number of the last sector to be checked on

each side of the disk. If EOT is greater than the

number of sectors per side, the command termi-

nates with an error and no useful Address Mark

(AM) or CRC data is returned.

Ninth Command Phase Byte,

Sectors to Read Count (SC)

This byte specifies the number of sectors to read.

If the Enable Count (EC) control bit (bit 7) of the

second command byte is 0, this byte is not needed

and should be set to the value FF (hex).

Execution Phase

Data is read from the disk, as the controller checks for

valid address marks in the address and data fields.

This command is identical to the READ DATA com-

mand, except that it does not transfer data during the

execution phase. See “The READ DATA Command”

on page 105.

If the Multi-Track (MT) parameter is 1 and SC is great-

er than the number of remaining formatted sectors on

side 0, verification continues on side 1 of the disk.

Result Phase

Table 61 shows how different conditions affect the ter-

mination status.

7654

3210

MFM

0110

DS1

DS0

Track Number

Head Number

Sector Number

Bytes-Per-Sector Code

End of Track (EOT) Sector Number

Bytes Between Sectors - Gap 3

Sectors to read Count (SC)

7654

3210

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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