PC87332VLJ-5 NSC [National Semiconductor], PC87332VLJ-5 Datasheet - Page 46

• Manufacturer Part Number: PC87332VLJ-5
• Description: PC87332VLJ (3.3V/5V) and PC87332VLJ-5 (5V) (SuperI/OTM III Premium Green) Floppy Disk Controller, Dual UARTs, IEEE1284 Parallel Port, and IDE Interfac
• Manufacturer: NSC [National Semiconductor]

4 0 FDC Command Set Description
SCAN LOW OR EQUAL
Command Phase
Execution Phase Data transferred from system to control-
ler is compared to data read from disk
Result Phase
4 1 16 Seek Command
The Seek command steps the selected drive in or out until
the desired track number is reached During the Execution
Phase of the Seek command the track number to seek to is
compared with the present track number The controller will
determine how many step pulses to issue and the DIR disk
interface output will indicate which direction the R W head
should move The DRx BUSY bit is set in the MSR for the
appropriate drive The controller will wait the Motor On time
before issuing the first step pulse
After the Motor On time the controller will enter the Idle
Phase The execution of the actual step pulses occurs in the
Drive Polling phase of the controller The step pulse rate is
determined by the value programmed in the Specify com-
mand An interrupt will be generated one step pulse period
after the last step pulse is issued A Sense Interrupt com-
mand should be issued to determine the cause of the inter-
rupt There is no Result Phase
While the internal microengine is capable of performing
seek commands on 2 or more drives at the same time soft-
ware should ensure that only one drive is seeking at a time
This is because the drives are actually selected via the
DOR which can only select one drive at a time No other
command except a Sense Interrupt command should be is-
sued while a Seek command is in progress
If the extended track range mode is enabled with the ETR
bit in the Mode command a fourth command byte should be
written in the Command Phase to indicate the four most
significant bits of the desired track number Otherwise only
three command bytes should be written
MT
IPS
MFM
X
End of Track Sector Number
SK
X
Intersector Gap Length
Drive Head Number
Status Register 0
Status Register 1
Status Register 2
Bytes per Sector
Sector Step Size
Bytes per Sector
Sector Number
Sector Number
Track Number
Track Number
Head Number
1
X
X
1
HD
0
DR1
0
DR0
1
(Continued)
46
Command Phase
Note The last Command Phase byte is required only if ETR is set in Mode
Execution Phase Disk drive head is stepped in or out to a
programmed track
Result Phase None
4 1 17 Sense Drive Status Command
The Sense Drive Status command returns the status of the
selected disk drive in ST3 This command does not gener-
ate an interrupt
Command Phase
Execution Phase Disk drive status information is detected
and reported
Result Phase
4 1 18 Sense Interrupt Command
The Sense Interrupt command is used to determine the
cause of an interrupt when the interrupt is a result of the
change in status of any disk drive
Command Phase
Execution Phase Status of interrupt is reported
Result Phase
Note The third Result Phase byte can only be read if ETR is set in the Mode
Four possible causes for the interrupt are
1 Entry into the Result Phase of any of the following com-
2 Occurrence of a data transfer in the Execution Phase
mands
a
b
c
d
e
f
g
h
i
while in the Non-DMA mode
0
X
0
X
0
Command
Command
MSN of Track Number
Read Data
Read Deleted Data
Read a Track
Read ID
Write Data
Write Deleted Data
Format
Scan
Verify
0
X
MSN of PTR
0
X
0
0
X
Present Track Number (PTR)
X
0
0
New Track Number
X
Status Register 3
Status Register 0
0
X
0
0
X
0
X
1
0
1
0
HD
1
HD
1
0
0
0
DR1
0
DR1
1
0
0
0
DR0
DR0
0
1
0
0
0