PC87332VLJ-5 NSC [National Semiconductor], PC87332VLJ-5 Datasheet - Page 39

• 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
FRD FIFO Read Disable for
BST Burst Mode Disable Default after a software reset if
R255 Recalibrate Step Pulses The bit determines the
DENSEL Density Select Pin Configuration This 2-bit value
When TUP bit 1
When TUP bit 1
Data Rate
2 Mbps
250 kbps
300 kbps
500 kbps
1 Mbps
0
LOCK is 0 If LOCK is 1 BST retains its value after a
software reset
Note This bit is only valid if the FIFO is enabled in the Configure
0
1
troller Default after a software reset if LOCK is 0 If
LOCK is 1 FRD retains its value after a software re-
set
Note This bit is only valid if the FIFO is enabled in the Configure
1
0
maximum number of recalibrate step pulses the con-
troller issues before terminating with an error De-
fault after a software reset
1
e
e
e
e
e
e
TABLE 4-3 DENSEL Default Encoding
configures the Density Select output to one of
three possible modes The default mode config-
ures the DENSEL pin according to the state of
the IDENT input pin after a data rate has been
selected That is if IDENT is high the DENSEL
pin
1 Mbps 2 Mbps data rates If IDENT is low the
DENSEL
500 kbps 1 Mbps 2 Mbps data rates See Table
4-3 In addition to these modes the DENSEL out-
put can be set to always low or always high as
shown in Table 4-4 This allows the user more
flexibility with new drive types
Burst mode enabled for FIFO Execution Phase
data transfers
Enable FIFO
cution Phase use the internal FIFO
Non-Burst mode enabled The DRQ or IRQ6 pin
is strobed once for each byte to be transferred
while the FIFO is enabled
Disable FIFO All read data transfers take place
without the FIFO
command If the FIFO is not enabled in the Configure com-
mand then this bit is a don’t care
command If the FIFO is not enabled in the Configure com-
mand then this bit is a don’t care
Maximum of 85 recalibrate step pulses If ETR
e
pulses maximum
Maximum of 255 recalibrate step pulses If ETR
e
brate step pulses
e
e
1 controller issues 3925 recalibrate step
1 controller issues 4095 maximum recali-
is
1 a Data Rate of 2 Mbps is selected
0 a Data Rate of 1 Mbps is selected
active
pin
IDENT
P read transfers during the Exe-
High
High
High
Low
Low
DENSEL Pin Definition
high
is
e
P read transfers from con-
1
active
for
the
low
IDENT
500
High
High
Low
Low
Low
for
e
kbps
0
the
(Continued)
39
BFR CMOS Disk Interface Buffer Enable
WLD Scan Wild Card
Head
Settle Time allowed for read write head to settle after a
RG Read Gate Diagnostic
PU PUMP Pulse Output Diagnostic
4 1 7 NSC Command
The NSC command can be used to distinguish between the
FDC versions and the 82077 The Result Phase byte
uniquely identifies the floppy controller as a PC87334 which
returns a value of 73h The 82077 and DP8473 return a
value of 80h signifying an invalid command The lower four
bits of this result byte are subject to change by National
and reflects the particular version of the floppy disk control-
ler part
Command Phase
Execution Phase None
Result Phase
0
0
(kbits sec)
Data Rate
0
1
0
1
0
1
Bit 1
e
0
e
1
e
1000
e
seek during an Implied Seek operation This is con-
trolled as shown in Table 4-5 by loading a 4-bit value
for N (The default value for N is 8 )
0
0
1
1
e
250
300
500
e
TABLE 4-5 Head Settle Time Calculation
e
e
Enable MFM output pin for normal operation
Enable DSKCHG disk interface input for normal
operation
Enable the MFM output to act as an internal serial
data in signal
Enable DSKCHG to act as an external Read Gate
input signal to the Data Separator This is intend-
ed as a test mode to aid in evaluation of the Data
Separator
Drive output signals configured as standard 4 mA
push-pull outputs (actually 40 mA sink 4 mA
source)
Drive output signals configured as 40 mA open-
drain outputs
0
1
An FFh from either the
Scan command is interpreted as a wildcard
character that always matches true
The Scan commands do not recognize FFh as a
wildcard character
TABLE 4-4 DENSEL Encoding
0
1
Bit 0
(4 Bit Value)
N
0
1
0
1
Multiplier
1
1
N
N
N
c
c
c
c
6 666
8
4
2
1
0
P or the disk during a
Pin Definition
0
0
Undefined
DEFAULT
DENSEL
Pin High
Pin Low
Head Settle
Time (ms)
0– 120
0 – 100
0–60
0–30
0
1
0
1