HP 5300A - Signal Name

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Model 5300A
Theory of Operation
Table 4-2. A1J1 Signals (Continued)
PIN NO. SIGNAL NAME
DP2
RIGHT/LEFT
DIGIT ADDRESS X
DIGIT SELECT X
DIGIT ADDRESS Y
DIGIT SELECT Y
DIGIT ADDRESS Z
DIGIT SELECT Z
DATA "D"
DATA "C"
DATA "B"
DATA "A"
DP3
is supplied, one digit at a time, starting with the least
significant digit. The output information is synchro-
nized with the display scan and is continuously
recycled with the display. The buffered Data Clock
signal at AlJ2(A6) is derived from A1U1 Scanner
right/left (R/L) code. The data changes immediately
after the Data Clock goes low. .
4-51. A START DATA signal at AlJ2(B4) is derived
from the A1U1 Scanner 5L output. This signal
immediately precedes the start of a new scan cycle.
Although the new scan may begin with a decimal
point, the START DATA signal always corresponds
with the last or most significant digit and never with a
decimal point. The decimal point is included in the
data sequence and is inserted at the correct position
as
a
binary
15
code.
This
code
corresponds
with
a
printed
asterisk
(*)
on
the
standard
print
wheel
of
HP
Digital
Recorders.
The
asterisk
is
used
in
place
of
a
decimal
point,
and
the
decimal
point
code
is
inserted
during
the
time
when
the
right-hand
half
of
the
cor-
responding
digit
is
being
scanned.
A
positive
decimal
clock
pulse
is
simultaneously
generated
by
an
array
of
common
collector
transistors,
Q19
to
Q24.
The
Q19
to
Q24
emitters
are
tied
to
the
decimal
point
driving
lines
and
the
bases
are
driven
from
the
A1U1
Scanner
outputs.
The
appropriate
transistor
is
turned
on
when
the
Scanner
reaches
the
decimal
point
position.
This
forces
all
outputs
of
A1U6
buffer
gates
to
a
high
level
(binary
15)
and
provides
the
decimal
point
clock
to
Low
signal
activates
decimal
point
2.
Code
indicating
half
character
which
is
being
addressed.
High
when
right-hand
of
character
is
displayed.
Digit
address
code
X,
Y,
Z
from
the
display
scanner
indicates
a
digit
being
displayed.
Digit
select
code
X,
Y,
Z
is
the
corresponding
code
which
selects
the
digit
at
the
output
of
the
counter.
If
the
main-
from
counter
is
displayed
directly
the
corresponding
lines
of
the
digit
address
code
and
the
digit
select
code
are
con-
connected
together.
The
data
code
A,
B,
C,
D
represents
the
digit
to
be
displayed
in
binary
coded
decimal
form.
Data
lines
can
carry
the
counter
output
information
tothe
plug-on
as
well
as
to
the
display
or
can
bypass
the
counter
and
bring
plug-on
data
to
the
display.
Low signal activates decimal point 3.
Low signal activates decimal point 4.
Low signal activates decimal point 5.
Ground
DC
power
to
power
supply
from
battery
pack
or
from
22
volt
input
power
from
pin
25.
DESCRIPTION
A1U7
buffer
inverter.
If
no
decimal
point
is
lighted,
the
decimal-point-common
voltage
increases
and
turns
on
A1Q18.
This
inserts
a
decimal
point
to
the
right
of
the
display.
4-52.
The
measurement
units
information
(MHz,
kHz,
Hz,
etc.)
is
sent
to the
digital
recorder
output
as
direct
signals
from
the
plug-on
connector
in
parallel
with
the
signals
to
the
display
annunciator.
The
print
com-
mand
from
the
plug-on
connector,
Al1J1(19),
is
buffered
to
provide
a
positive
print
command
to
the
digital
recorder.
This
signal
is
normally
derived
from
the
A1U5
Control
TRANSFER
output
and
is
con-
nected
via
AlJ1(19)
and
(20).
The
HOLD
signal
from
the
digital
recorder
output
to
A1U5
prevents
the
instrument
from
recycling
until
the
digital_recorder
has
accepted
the
data.
A
low
signal
on
the
HOLD
line
inhibits
the
display
cycle
prior
to
the
RESET
signal.
4-53. The RESET signal line is a bi-directional line in
parallel with the Manual Reset button on the 5300A
front panel. It may be used as an input to reset the
instrument from the rear-panel or an output to inhibit
the printing of all zeros when the instrument is reset.
The overflow output is in parallel with the overflow
light in the Display Assembly and goes low when dis-
play overflow occurs. The +5 volt supply line is avail-
hes at AlJ2 Digital Recorder Connector for external
ogic.
4-13