-
MZ-5600
IlPD765 Pin functions
Table 22
Pin
No.
Function
I/O
Description
40
VCC
-
+5V
20
GND -
OV
19
q,
I Single-phase clock (TTL compatible)
1
RESET
I
Places
the
FDC in
the
idle
state
and
sets all
the
drive interface
outputs
to
low, with
the
exception of
PSO,
PS1,
and
WoATA
(indefinite)
outputs.
Also sets
the
INF
and
ORa
outputs
to
low.
The
DB
is
placed
int
he
input
state.
4
CS
I
Makes
the
Ro
and
WR
lignals valid.
13-6
oB7-oBO
I/O
Bidirectional, three-state
data
bus.
3
WR
I
Control signal
sued
~
write
data
into
the
F
DC
via
the
data
bus.
2
Ro
I
Control signal
used
to
read
data
out
of
the
FoC
via
the
data
bus.
-
;
INT
Indic:8tes
the
FDC
is
requesting service. During
non·oMA
mode,
this
is
output
for
each transfer byte;
18
0
clIring
oMA
mode,
this
is ou1pUt
at
the
end
of
command
execution.
5
AO
I
Selects
the
status
and
data
registers within
the
FDC which are
to
be
accessed
through
the
data bus.
If
AD
is
zero,
the
status
register is selected; if
it
is
one,
the
data
register
is
selected.
14
ORa
0
DMA
request
used
to
r-equat
DMA
trwmar
~n
the
FoC
and
memory.
15
DACK
I
Indicates
a DMA request-has been acknowledged. During
oMA
cycles, this signal functions
in
the
same way as
the
CS.
-
29,28
usa,
1
0
Drive select lines. Up
to
four
Foo's
can
be
selected
by
decoding these
two
lines.
26
MFM
0
Specifies
the
VFO
logic
operation
mode.
If MFM
is
one,
specifies
the
MFM
mode;
if
MFM
is
zero,
specifies
the
FM
mode.
24 SYNC 0
Specifies
the
VFO
logic
operation
mode.
If
SYNC
is
one,
read operation
is
enabled;
if
it
is
zero, read
operation
is
disabled.
39
RW/SEEK 0
Distinguishes between
the
signal which functions as
both
read/write
and
seek signals, from the drive
interface signals.
If
RW/SEEK
is
zero, indicates RIW; if
it
is
one,
indicates SEEK.
36 HOLD 0
Loads
the
read/write head
in
the
drive.
27
SIDE 0
Selects head 0
or
1
of
a double-sided drive.
If
SIDE
is
zero, head 0
is
selected;
if
it
is
one, head 1
is
selected.
38
LCT/DIR 0
If
the
R/W SEEK signal specifies RIW, this signal functions as
the
LCT
to
indicate
the
drive's read/
write head
is
accessing cylinder
43
or
above.
If
the
RIW SEEK signal specifies SEEK, this signal func·
tions as
the
DIR, which specifies
the
direction of
the
seek operation.
If
DIR
is
zero, a seek operation
is
done
toward
the
edge
of
the
disk;
if
it
is
one,
the
seek operation
is
done
toward
the
center of
the
disk.
37 FL TR/STEP
0
If
the
RIW SEEK signal specifies R/W, this signal functions as
the
FLTR and
is
used
to
reset
the
fault
condition
which
is
retained
on
the
drive.
If
it specifies SEEK, this signal functions as
the
STEP
and
~
becomes
the
step
signal for seek.
35
READY
I Indicates
the
drive
is
in
the
ready state.
34
WPRT/2 SIDE
I
If
the
RIW SEEK signal specifies
RW,
this signal functions as
the
WPRT
to
indicate
the
drive
or
rfIIKtium
is
write
protected.
If
it specifies SEEK, this signal becomes 2 SIDE
to
indicate a double,sided
medium is placed in
the
drive.
17
INDEX
I
Indicates
the
physical beginning
of
the
tracks on
the
medium.
33
FL
T/TRKO
I
If
the
RIW
SEEK
signal specifies
RW,
this signal functions as
the
F LT
to
indicate
the
drive
is
in
the
fault
state.
If it specifies SEEK, this signal functions as
the
TRKO
to
indicate
the
read/write head
is
positioned
on
cylinder O.
16
TC
I
Indicates
the
completion
of
a read
or
write operation from
the
host system.
30
WDATA 0
Write
data
to
the
drive, comprised
of
clock
and
data bits.
25
WE
0 Specifies a write operation
to
the
drive.
-41-
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