FLOPPY DISK CONTROLLER
FLOPPY DISK CONTROLLER INTERNAL REGISTERS
The Floppy Disk Controller (FDC) provides the interface
between a host microprocessor and the floppy disk
The Floppy Disk Controller contains eight internal
registers which facilitate the interfacing between the host
microprocessor and the disk drive. Table 2 shows the
addresses required to access these registers. Registers
other than the ones shown are not supported. The rest of
the FDC description assumes the Base I/O Address is
3F0.
drives.
The FDC integrates the functions of the
Formatter/Controller, Digital Data Separator, Write
Precompensation and Data Rate Selection logic for an
IBM XT/AT compatible FDC. The true CMOS 765B core
guarantees 100% IBM PC XT/AT compatibility in addition
to providing data overflow and underflow protection.
The FDC37C669 is compatible to the 82077AA
using SMSC's proprietary floppy disk controller core.
Table 2 - Status, Data and Control Registers
BASE I/O
ADDRESS
REGISTER
+0
+1
+2
+3
+4
+4
+5
+6
+7
+7
R
R
Status Register A
SRA
SRB
DOR
TSR
MSR
DSR
FIFO
Status Register B
R/W
R/W
R
Digital Output Register
Tape Drive Register
Main Status Register
Data Rate Select Register
Data (FIFO)
W
R/W
Reserved
R
Digital Input Register
Configuration Control Register
DIR
W
CCR
For information on the floppy disk on Parallel Port pins, refer to Configuration Register CR4 and Parallel Port
Floppy Disk Controller description.
18
SMSC [ SMSC CORPORATION ]
