GM82C765B Datasheet, PDF (22/36 Pages) Hynix Semiconductor – FLOPPY DISK SUBSYSTEM CONTROLLER

∗ _{COMMAND PARAMETERS}
The GM82C765B is capable of performing 15
different commands. Each command is initiated by a
multibyte transfer from the processor. The results
after execution of the command may also be a
multibyte transfer back to the processor. The
commands consist of three phases : Command phase,
Execution phase, and the Result phase.
Command phase − The Floppy Disk Controller
(FDC) receives all information
required to perform a
particular operation from the
processor.
Execution phase − The FDC performs the operation
it was in structed to do.
Result phase − After completion of the operation,
status and other housekeeping in
formation are made available to the
processor
GM82C765B
TABLE 10. GM82C765B COMMANDS
READ DATA
READ DELETED DATA
WRITE DATA
WRITE DELETED DATA
READ A TRACK
READ ID
FORMAT A TRACK
SCAN EQUAL
SCAN LOW OR EQUAL
SCAN HIGH OR EQUAL
Table 10. lists the 15 GM82C765B commands.
Table 11. through 25 are presented to show the
required parameters and results for each command.
Most commands require nine command bytes during
the result phase. The “W” to the left of each byte
indicates a command phase byte to be written. An
“R” indicates a result byte.
TABLE 11. READ DATA
PHASE
COMMAND
EXECUTION
RESULTS
R/W D7 D6 D5 D4
W MT MF SK 0
W
XX XX
D3 D2 D2 D0
REMARKS
0
X
1
HS
1
US1
0
US0
Command Codes
W
C
Sector ID information prior to
W
H
command execution. The four bytes
W
R
are compared against header on
W
N
floppy disk.
W
EOT
W
GPL
W
DTL
Data transfer between FDD and main
system
R
STO
Status information after command
R
ST1
execution.
R
ST2
R
C
Sector ID information after command
R
H
execution.
R
R
R
N
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