PC87307 datasheet(91/218 Pages) NSC

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TABLE 5-12. Typical Gap 3 Values

FIGURE 5-20. IBM, Perpendicular, and ISO Formats Supported by the FORMAT TRACK Command

a. Gap 2 is speciﬁed in the command phase of read, write, scan, and verify commands. Although this is the recom-

mended value, the FDC ignores this byte in read, write, scan and verify commands.

b. Gap 3 is the suggested value for use in the FORMAT TRACK command. This is the programmable Gap 3 illus-

trated in Figure 5-20.

Drive Type and

Data Transfer

Rate

Bytes in Data

Field (decimal)

Bytes-Per-Sector

Code (hex)

End of Track (EOT)

Sector # (hex)

Bytes in Gap 2 a

(hex)

Bytes in Gap 3 b

(hex)

256

250 Kbps

512

MFM

512

1024

2048

4096

500 Kbps

256

MFM

512

1024

2048

4096

8192

Gap 0

80 of

SYNC

12 of

IAM

3 of

C2* FC

Gap 1

50 of

3 of

A1*

Gap 2

22 of

SYNC

12 of

SYNC

12 of

3 of

A1*

Data

Gap 3

Program-

able

Gap 4

Gap 0

80 of

SYNC

12 of

IAM

3 of

C2* FC

Gap 1

50 of

3 of

A1*

Gap 2

41 of

SYNC

12 of

SYNC

12 of

3 of

A1*

Data

Gap 3

Program-

able

Gap 4

Gap 1

32 of

3 of

A1*

Gap 2

22 of

SYNC

12 of

SYNC

12 of

3 of

A1*

Data

Gap 3

Program-

able

Gap 4

Index Pulse

IBM

Format

(MFM)

Perpendicular

Format

ISO

Format

(MFM)

Index

Field

Address Field

Data Field

Repeated for each sector

A1* = Data Pattern of A1, Clock Pattern of 0A. All other data rates use gap 2 = 22 bytes.

C2* = Data Pattern of C2, Clock Pattern of 14

Toshiba

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