FDC37M81 SMSC [SMSC Corporation], FDC37M81 Datasheet - Page 62

• Manufacturer Part Number: FDC37M81
• Description: PC98/99 Compliant Enhanced Super I/O Controller with Keyboard/Mouse Wake-Up
• Manufacturer: SMSC [SMSC Corporation]

Note that if implied seek is not enabled, the read
and write commands should be preceded by:
1) Seek command - Step to the proper track
2) Sense
3) Read ID - Verify head is on proper track
4) Issue Read/Write command.
The Seek command does not have a result
phase. Therefore, it is highly recommended that
the Sense Interrupt Status command is 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
recommended that the user service all pending
interrupts through the Sense Interrupt Status
command.
Sense Interrupt Status
An interrupt signal is generated by the FDC for
one of the following reasons:
1. Upon entering the Result Phase of:
Terminate the Seek command
a. Read Data command
b. Read A Track command
c. Read ID command
d. Read Deleted Data command
e. Write Data command
Interrupt
command,
Status
it
command
is
highly
-
62
f. Format A Track command
2. End of Seek, Relative Seek, or Recalibrate
3. FDC requires a data transfer during the
The Sense Interrupt Status command resets the
interrupt signal and, via the IC code and SE bit
of Status Register 0, identifies the cause of the
interrupt.
The Seek, Relative Seek, and Recalibrate
commands have no result phase. The Sense
Interrupt Status command must be issued
immediately after these commands to terminate
them and to provide verification of the head
position (PCN). The H (Head Address) bit in
ST0 will always return a "0". If a Sense Interrupt
Status is not issued, the drive will continue to be
BUSY and may affect the operation of the next
command.
g. Write Deleted Data command
h. Verify command
command
execution phase in the non-DMA mode
SE
0
1
1
Table 26 - Interrupt Identification
11
00
01
IC
Polling
Normal termination of Seek
or Recalibrate command
Abnormal termination of
Seek or Recalibrate
command
INTERRUPT DUE TO