DP8473 Floppy Disk Controller PLUS-2
July 1990
DP8473 Floppy Disk Controller PLUS-2
TM
General Description
This controller is a full featured floppy disk controller that is
software compatible with the
mPD765A
but also includes
many additional hardware and software enhancements
These enhancements include additional logic specifically re-
quired for an IBM PC PC-XT PC-AT or PS 2 design
This controller incorporates a precision analog data separa-
tor that includes a self trimming delay line and VCO Up to
three external filters are switched automatically depending
on the data rate selected This provides optimal perform-
ance at the standard PC data rates of 250 300 kb s and
500 kb s It also enables optimum performance at 1 Mb s
(MFM) These features combine to provide the lowest possi-
ble PLL bandwidth with the greatest lock range and hence
the widest window margin
This controller includes write precompensation circuitry A
shift register is used to provide a fixed 125 ns early-late
precompensation for all tracks at 500k 300k 250 kb s (83
ns for 1 MB s) or a precompensation value that scales with
(Continued)
Features
Y
Y
Y
Y
Y
Y
Fully
mPD765A
and IBM-BIOS compatible
Integrates all PCXT PCAT and most PS 2 Logic
On chip 24 MHz Crystal Oscillator
DMA enable logic
IBM compatible address decode of A0 鈥?A2
12 mA
mP
bus interface buffers
48 mA floppy drive interface buffers
Data rate and drive control registers
Precision analog data separator
Self-calibrating PLL and delay line
Automatically chooses one of three filters
Intelligent read algorithm
Two pin programmable precompensation modes
Other enhancements
up to 1 Mb s data rate
Implied seek up to 4000 tracks
IBM or ISO formatting
Low power CMOS with power down mode
Connection Diagrams
Plastic Leaded Chip Carrier
Dual-In-Line Package
TL F 9384 鈥?1
Top View
Order Number DP8473V
See NS Package Number V52A
TL F 9384 鈥?2
Top View
TRI-STATE is a registered trademark of National Semiconductor Corporation
PLUS-2
TM
is a trademark of National Semiconductor Corporation
IBM PCXT PCAT and PS 2 are registered trademarks of International Business Machines Corporation
C
1995 National Semiconductor Corporation
TL F 9384
Order Number DP8473N
See NS Package Number N48A
RRD-B30M105 Printed in U S A