82091AA Datasheet, PDF (155/204 Pages) Intel Corporation – ADVANCED INTEGRATED PERIPHERAL (AIP)

82091AA
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 verifi-
cation of the head position (PCN) The H bit (Head
Address) in ST0 will always return a 0 When exiting
DSR Powerdown mode the FDC clears the PCN
value and the status information to zero Prior to is-
suing the DSR POWERDOWN Command it is highly
recommended that the user service all pending in-
terrupts through the SENSE INTERRUPT STATUS
Command
8 5 3 5 SENSE INTERRUPT STATUS Command
An interrupt signal on the INT pin is generated by the
FDC for one of the following reasons
1 Upon entering the Result Phase of
a READ DATA Command
b READ TRACK Command
c READ ID Command
d READ DELETED DATA Command
e WRITE DATA Command
f FORMAT TRACK Command
g WRITE DELETED DATA Command
h VERIFY Command
2 End of SEEK RELATIVE SEEK or
RECALIBRATE Command
3 FDC requires a data transfer during the execution
phase in the non-DMA Mode
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 inter-
rupt If a SENSE INTERRUPT STATUS Command is
issued when no active interrupt condition is present
the status register ST0 will return a value of 80h
(invalid command)
The SEEK RELATIVE SEEK and the RECALI-
BRATE Commands have no result phase The
SENSE INTERRUPT STATUS Command must be
issued immediately after these commands to termi-
nate 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 effect the operation of the next command
8 5 3 6 SENSE DRIVE STATUS Command
The SENSE DRIVE STATUS Command obtains
drive status information It has no execution phase
and goes directly to the result phase from the com-
mand phase STATUS REGISTER 3 contains the
drive status information
8 5 3 7 SPECIFY Command
The SPECIFY Command sets the initial values for
each of the three internal timers The HUT (Head
Unload Time) defines the time from the end of the
execution phase of one of the read write commands
to the head unload state The SRT (Step Rate Time)
defines the time interval between adjacent step
pulses Note that the spacing between the first and
second step pulses may be shorter than the remain-
ing step pulses The HLT (Head Load Time) defines
the time between the command phase to the execu-
tion phase of a READ DATA or Write Data Com-
mand The Head Unload Time (HUT) timer goes
from the end of the execution phase to the begining
of the result phase of a READ Data or Write Data
Command The values change with the data rate
speed selection and are documented in Table 34
Table 33 Interrupt Identification
SE
IC
Interrupt Due To
0
11
Polling
1
00
Normal Termination of SEEK or RECALIBRATE Command
1
01
Abnormal Termination of SEEK or RECALIBRATE Command
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