D765 Ver la hoja de datos (PDF) - NEC => Renesas Technology
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D765 Datasheet PDF : 17 Pages
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uPD765A/ uPD765B
Command Symbol Description (cont)
SRT
(Step Rate Time)
STO-ST3
(Status O-3)
SRT stands for the steooino rate for the FDD (1 to
16 ms in 1 ms increments). Stepping rate applies
to all drives (FH=1ms, EH=2ms, etc.).
STO-ST3 stands for one of four registers which
store the status information after a command has
been executed. This information IS available dur-
ing the result phase after command execution.
These registers should not be confused with the
main status register (selected by Ao=O).
STO-ST3 may be read only after a command has
been executed and contains information relevant
to that particular command
Command Symbol Description (cont)
Name
STP
US0, US1
(Unit Select)
Function
During a scan operation if STP=1, the data in
contiguous sectors is compared byte by byte with
data sent from the processor (or DMA); and if
STP=2, then alternate sectorsare read and com-
pared
US stands for a selected drive number 0 or 3
Table 4. Instruction Set (Notes 1,2)
Phase
Read Data
Command
Instruction Code
R/W
D7 D6 D5 D4 D3 D2 D1 D0
w
MT MF SK 0 0 1
10
W
X X X X X HD US1 US0
W
C
W
H
w
R
W
N
W
EOT
w
GQL
w
DTL
Execution
Result
ST0
ST1
ST2
C
H
R
R
R
N
Read Deleted Data
Command
W
MT MF SK 0 1 1 0 0
W
X X X X X HD US, US0
W
C
W
H
W
R
w
N
W
EOT
W
GPL
W
DTL
Execution
Result
ST0
ST1
ST2
C
H
R
R
RR
N
Note:
(1) Symbols used in this table are described at the end of this section
(2) A0 should equal 1 for all operations.
(3) X = Don’t care, usually made to equal 0.
Remarks
Command codes
(Note 3)
Sector ID
prior to command execution
are compared against header on floppy disk.
The 4 bytes
Data transfer between the FDD and main system
Status Information after command execution
Sector ID Information after command execution
Command codes
Sector ID rnformation to command execution The 4 bytes
are compared against header on floppy disk
Data transfer between the FDD and main system
Status information after command execution
Sector ID information after command execution
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