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參數(shù)資料
| 型號： | UPD765A |
| 廠商： | NEC Corp. |
| 英文描述： | Single/Double Density Floppy-Disk Controller |
| 中文描述： | 單/雙密度軟盤控制器 |
| 文件頁數(shù)： | 10/17頁 |
| 文件大小： | 344K |
| 代理商： | UPD765A |
uPD765A/uPD765B
NEC
Table 3. Status
Register Identification
Pin
NO.
Status Register 0
Name
D7,
D6
IC
(Interrupt Code)
Function
D7=0 and D6=0
Normal
termnation
of command, (NT)
Command was completed and properly ex-
ecuted
D7=0 and D6=1
Abnormal termnation of command, (AT)
Execution
of command was started but
was not
successfully
D3
N R
(Not Ready)
completed.
D7=1 and D6=0
Invalid command issue,
(IC)
Command
which was issued was never started
D7=1 and D6=1
Abnormal
termnation
because during
command execution the ready srgnal from
FDD changed state
When the FDC completes the Seek
com-
mand, this flag
IS
set lo
1
(high).
If
a fault srgnal
IS
received
fromthe FDD, or
if the track 0 srgnal
fails
to occur after 77
step pulses (Recalibrate Command) then
this flag is set
When the FDD
IS
in
the not-ready state
and
a Read or Write command
IS
Issued, this
flag
IS
set If a Read or Write command is
issued to
side
1 of a
single-sided drive,
then
this flag
IS
set
This
flag
IS
used to
indicate
the state of the
head
at interrupt.
This flag
IS
used to
indicate
a
drive
unit
number at interrupt.
This
flaa is used to Indicate a drive
unit
number at
interrupt
D65
D4
S E
(Seek End)
E C
(Equipment Check)
D2
H D
(Head Address)
US:
(Unit Select 1)
Us0
(Unit
Select 0)
D1
D0
Status Register
1
D7
EN
(End of
Cylinder)
When the FDC tries to access a
sector
be-
yond the final sector of a
cylinder,
IS
set
Not used. This
bit
is
always 0 (low)
When the FDC detects a
CRC(1)
error in
ei-
ther the
ID field or the data field,
this
flag
is
set
If the FDC
is
not
serviced
by the host
sys-
tem during
data transfers
within
a
certain
time interval.
this
flaa
is
set.
Not used. This
bit is
alwavs 0 (low).
this
flag
DE Daa
Error)
D4
OR
(Overrun)
D3
Table
3. Status Register Identification
(cont)
Pin
NO.
Status
Register
1
(cont)
D2
ND
(No Data)
Name
Function
During
execution
of Read Data. Read
De-
leted
Data
Write Data.
Write
Deleted Data
or Scan command, if the FDC cannot find
the sector
specified
in
the
IDR(2)
Register,
this flag
is
set.
D1
NWNo Writeable)
Do
MA
(Missing
Address
Mark)
During
execution of
the Read ID command.
if the
FDC
cannot read the ID
field
without
an error, then this flag
IS
set.
During execution of the Read
Diagnostic
command.
if
the
starting
sector cannot be
found, then this flag is set.
During
execution of Write Data, Write De-
leted Data or Write
ID command.
if
the FDC
detect: a
write
protect srgnal
from
the
FDD. then this flag is Set
This bit
is set
if
the FDC does not detect the
IDAM
before 2
index
pulses It is
also
set if
the FDC cannot
find
the DAMor DDAMaf-
ter the
IDAM
is
found. MD bit of ST2
is
also
ser at
this
time.
Status Register 2
D7
De
Not
used. This bit
IS
alwavs 0 (low)
During
execution
of the Read Data or Scan
command, if the FDC encounters a sector
which contains a deleted data address
mark,
this
flag is set Also set if DAM is
found during Read Deleted Data
If the
FDC
detects a CRC error
in
the data
field
then
this
flag is set
CM
(Control Mark)
D5
DD
(Data Error
in
Data
Field)
DA
W C
(Wrong
Cylinder)
This
bit
IS
related to the ND
bit,
and when
the contents of C(3) on the mediumis
dif-
ferent
fromthat stored
in
the IDR.
this
flag
is set
During
execution
of the Scan command.
if
the
condition
of “equal” is
satisfied,
flag
is
set.
During
execution
of the Scan command,
if
the
F D
cannot find a sector on the cylin-
der which meets the condition. then
Cthis
flag
is
set
This
bit
is
related to the ND bit. and when
the contents of C on the
medium
is
differ-
ent fromthat stored
in
the IDR and the con-
tents of C
IS
FFH. then this flag
IS
set
When data
IS
read fromthe
medium
if
the
FDC cannot find a data address mark or
deleted data address mark, then
this
flag
is set
D3
SH
(Scan Equal
Hit)
this
D2
SN
(Scan
Not Satisfied)
D1
B C
(Bad
Cylinder)
Do
MD
(Missing
Address
Mark
in
Data Field)
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