gm82c765b ETC-unknow, gm82c765b Datasheet - Page 22

• Manufacturer Part Number: gm82c765b
• Description: Floppy Disk Subsystem Controller
• Manufacturer: ETC-unknow

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
Execution phase
Result phase
TABLE 11. READ DATA
The GM82C765B is capable of performing 15
COMMAND PARAMETERS
EXECUTION
COMMAND
RESULTS
PHASE
status and other housekeeping in
formation are made available to the
processor
After completion of the operation,
The FDC performs the operation
it was in structed to do.
R/W
W
W
W
W
W
W
W
W
W
R
R
R
R
R
R
R
The Floppy Disk Controller
(FDC) receives all information
required
particular operation from the
processor.
MT
D7
X
MF
D6
to
X
perform
D5
SK
X
D4
X
0
a
EOT
DTL
GPL
STO
ST1
ST2
H
N
H
N
C
R
C
R
22
D3
X
0
TABLE 10. GM82C765B COMMANDS
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.
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
D2
HS
1
US1
D2
1
US0
D0
0
Command Codes
Sector ID information prior to
command execution. The four bytes
are compared against header on
floppy disk.
Data transfer between FDD and main
system
Status information after command
execution.
Sector ID information after command
execution.
REMARKS
GM82C765B