pc87317vul National Semiconductor Corporation, pc87317vul Datasheet - Page 122

• Manufacturer Part Number: pc87317vul
• Description: Pc87317vul/pc97317vul Superi/o Plug And Play Compatible With Acpi Compliant Controller/extender
• Manufacturer: National Semiconductor Corporation

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Execution Phase
Internal registers are written.
5.7.10 The READ DATA Command
The READ DATA command reads logical sectors that con-
tain a normal data address mark from the selected drive and
makes the data available to the host microprocessor.
Command Phase
The READ DATA command phase bytes must specify the
following ID information for the desired sector:
IPS
MT
7
GDC Bits
1
0
0
1
1
250, 300 or 500 Kbps
Track number
Head number
Sector number
Bytes-per-sector code (See TABLE 5-11 "Bytes per
Sector Codes" on page 116.)
TABLE 5-15. Effect of Drive Mode and Data Rate on FORMAT TRACK and WRITE DATA Commands
1 or 2 Mbps
MFM
Data Rates
X
6
0
1
0
1
End of Track (EOT) Sector Number
0
Bytes Between Sectors - Gap 3
SK
TABLE 5-16. Effect of GDC Bits on FORMAT TRACK and WRITE DATA Commands
X
Data Length (Obsolete)
5
Bytes-Per-Sector Code
Perpendicular (1 or 2 Mbps)
Perpendicular ( 500 Kbps)
Sector Number
Track Number
Head Number
X
4
0
Conventional
Conventional
Drive Mode
Perpendicular
Perpendicular
Conventional
Conventional
X
3
0
Drive Mode
HD
2
1
DS1
1
1
Length of Gap 2 in FORMAT
DS0
FORMAT TRACK Command
0
0
TRACK Command
Length of Gap 2 in
122
22 bytes
22 bytes
22 bytes
41 bytes
Result Phase
None.
After the last command phase byte is written, the controller
waits the Delay Before Processing time (see TABLE 5-25
"Constant Multipliers for Delay Before Processing Factor
and Delay Ranges" on page 132) for the selected drive.
During this time, the drive motor must be turned on by en-
abling the appropriate drive and motor select disk interface
output signals via the bits of the Digital Output Register
(DOR). See Section 5.3.3 "Digital Output Register (DOR)"
on page 97.
First Command Phase Byte
Bit 5 - Skip Control (SK)
Bit 6 - Modified Frequency Modulation (MFM)
Bit 7 - Multi-Track (MT)
22 bytes
22 bytes
22 bytes
41 bytes
End of Track (EOT) sector number. This allows the con-
troller to read multiple sectors.
The value of the data length byte is ignored and must be
set to FFh.
This controls whether or not sectors containing a delet-
ed address mark will be skipped during execution of the
READ DATA command. See TABLE 5-17 "Skip Control
Effect on READ DATA Command" on page 124.
0: Do not skip sector with deleted address mark.
1: Skip sector with deleted address mark.
This bit indicates the type of the disk drive and the data
transfer rate, and determines the format of the address
marks and the encoding scheme.
0: FM mode, i.e., single density.
1: MFM mode, i.e., double density.
This bit controls whether or not the controller continues
to side 1 of the disk after reaching the last sector of side
0.
Portion of Gap 2 Rewritten in
Portion of Gap 2 Rewritten in
WRITE DATA Command
WRITE DATA Command
19 bytes
38 bytes
0 bytes
0 bytes
19 bytes
38 bytes
0 bytes
0 bytes