PC8477BV-1 National Semiconductor, PC8477BV-1 Datasheet - Page 51

• Manufacturer Part Number: PC8477BV-1
• Description: IC ADVANCED FLOPPY CTRLR 68PLCC
• Manufacturer: National Semiconductor
• Series: SuperFDC™r

Specifications of PC8477BV-1

• Controller Type: Floppy Disk Controller
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 68-LCC (J-Lead)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Supply: -
• Interface: -
• Other names: *PC8477BV-1

Figure 7-2 shows a block diagram representing the initializa-
7 0 Reference Section
7 4 SOFTWARE INITIALIZATION SEQUENCE
Following power up the system will issue a hardware reset
to the PC8477B This will put the internal registers and cir-
cuitry into a known state after which the software initializa-
tion sequence can begin
End Reset The first task is to bring the PC8477B out of
the reset state by writing 0CH to the DOR register The
software should then poll the MSR until 80H is returned At
this point the controller is ready to begin processing com-
mands
Service Ready Changed State Interrupt Once an inter-
rupt is received the software should issue 4 SENSE INTER-
RUPT commands for each of the 4 logical drives This is
due to the fact that after a reset drive polling is enabled by
default
Set Data Rate The data rate should be set via a write to
the CCR register The default state is 250 kb s following
reset
Configure the FIFO The default setting is with the FIFO
disabled If the perpendicular format is to be supported the
FIFO will need to be enabled due to the higher data rates
used The FIFO threshold level should be set based on the
DMA response time of the system A lower value of
THRESH corresponds to a fast system with a quick DMA
response time whereas a higher value of THRESH corre-
sponds to a sluggish system with slower DMA response
time A write to the configuration register is also used to
enable implied seeks if that feature is desired
Lock This command will lock the FIFO parameters which
will leave them unaffected following a reset Set the LOCK
bit to 1 to lock the parameters
Specify Command After a reset a specify command must
always be issued in the initialization sequence This is be-
cause there is no default for these values With this com-
mand you will set up the motor on and motor off times as
well as the step rate times DMA mode is also enabled via
this command
Mode Command There are several advanced features
that can be enabled via the mode command Head settling
time for implied seeks open collector drive interface out-
puts ISO format pattern low power modes enabling 255
step pulses for higher density media and FIFO burst mode
are just some of the features
Recalibrate Drive First access to the drive should be to
RECALIBRATE to track 0 Following the recalibrate com-
mand it is necessary to issue a SENSE INTERRUPT com-
mand to determine if the recalibrate was successful If no
track 0 was detected an error will be reported This is a
common method to determine if a drive is connected
Seek Read Write Format At this point the initialization
is complete and normal disk I O operations would start to
occur In normal operations it would not be necessary to re-
initialize prior to each access Normal disk I O operations
would include writes to CCR register to change data rates
recalibrating to track 0 toggling the motor and drive selects
through the DOR register seeking to the appropriate track
and initializing the DMA controller prior to Read Write For-
mat commands
tion sequence for the PC8477B
(Continued)
51
7 5 PC8477A PC8477B DIFFERENCES
There are two differences to note between the 8477A and
8477B versions The NSC command result phase returns a
73H in the 8477B and returns a 72H in the 8477A This
command is used strictly to distinguish new revisions of the
part The second difference pertains to the Motor On Time
(MNT) values when the FDC is in Mode 1 The new table is
listed in Table 4-15 of this document The MNT values at
500 kb s for Mode 1 were changed to be the same as the
1 Mb s values The changes to the MNT values should not
affect application software
7 6 REVISION HISTORY
Nov 1990 Preliminary PC8477 datasheet
May 1992 Preliminary PC8477B datasheet
June 1993 Final PC8477B datasheet
Add new part markings
Add PQFP package option
Add 1 25 Mb s data rate support
Add Dynamic Window Margin spec
Improve ICC and AC databus timings
Add applications reference section
Elimination of 1 25 Mb s data rate support
Elimination of FM mode functional testing
ESD tolerance spec raised to 2000V
Replace t
Change t
Change t
RC
WDW
FIGURE 7-2 PC8477B Initialization
QK
spec from 160 ns to 300 ns
spec with t
300 Kb s from 416 ns to 375 ns
KR
and t
RK
TL F 11332 – 25