FDC37C672QFP SMSC Corporation, FDC37C672QFP Datasheet - Page 56

• Manufacturer Part Number: FDC37C672QFP
• Description: ENHANCED SUPER I/O CONTROLLER WITH FAST IR
• Manufacturer: SMSC Corporation

8.2.3
8.2.4
SMSC FDC37C672
SE bit in Status Register 0 is set to "1" and the command is terminated. If the nTR0 pin is still low after 79
step pulses have been issued, the FDC sets the SE and the EC bits of Status Register 0 to "1" and
terminates the command. Disks capable of handling more than 80 tracks per side may require more than
one Recalibrate command to return the head back to physical Track 0.
The Recalibrate command does not have a result phase. The Sense Interrupt Status command must be
issued after the Recalibrate command to effectively terminate it and to provide verification of the head
position (PCN). During the command phase of the recalibrate operation, the FDC is in the BUSY state, but
during the execution phase it is in a NON-BUSY state. At this time, another Recalibrate command may be
issued, and in this manner parallel Recalibrate operations may be done on up to four drives at once.
Upon power up, the software must issue a Recalibrate command to properly initialize all drives and the
controller.
Seek
The read/write head within the drive is moved from track to track under the control of the Seek command.
The FDC compares the PCN, which is the current head position, with the NCN and performs the following
operation if there is a difference:
PCN < NCN:
PCN > NCN:
The rate at which step pulses are issued is controlled by SRT (Stepping Rate Time) in the Specify
command. After each step pulse is issued, NCN is compared against PCN, and when NCN = PCN the SE
bit in Status Register 0 is set to "1" and the command is terminated. During the command phase of the
seek or recalibrate operation, the FDC is in the BUSY state, but during the execution phase it is in the
NON-BUSY state. At this time, another Seek or Recalibrate command may be issued, and in this manner,
parallel seek operations may be done on up to four drives at once.
Note that if implied seek is not enabled, the read and write commands should be preceded by:
1.
2.
3.
4.
The Seek command does not have a result phase. Therefore, it is highly recommended that the Sense
Interrupt Status command be issued after the Seek command to terminate it and to provide verification of
the head position (PCN). The H bit (Head Address) in ST0 will always return to a "0". When exiting
POWERDOWN mode, the FDC clears the PCN value and the status information to zero. Prior to issuing
the POWERDOWN command, it is highly recommended that the user service all pending interrupts
through the Sense Interrupt Status command.
Sense Interrupt Status
An interrupt signal on FINT pin is generated by the FDC for one of the following reasons:
1.
Seek command - Step to the proper track
Sense Interrupt Status command - Terminate the Seek command
Read ID - Verify head is on proper track
Issue Read/Write command.
Upon entering the Result Phase of:
a. Read Data command
b. Read A Track command
c. Read ID command
d. Read Deleted Data command
e. Write Data command
Direction signal to drive set to
Direction signal to drive set to
DATASHEET
Page 56
"1" (step in) and issues step pulses.
"0" (step out) and issues step pulses.
Enhanced Super I/O Controller with Fast IR
Rev. 10-29-03
Datasheet