Tektronix 7623, Instruction Manual

Page: 49 / 266

Circuit Description — 7623/R7623 Service
TABLE 3-1 (cont)
Basic Logic Reference
Device Symbol
Description
Set-Clear
(R-S) Flip-
Flop
A bistable device with two inputs
and two outputs (either or both
outputs may be used). The outputs
change state in response to the
states at the inputs. The outputs are
complementary (i.e., when one out­
put is HI the other is LO).
Input / Output
Input/Output Table
A
B X X
LO LO
Undefined
LO
HI LO
HI
HI LO
HI LO
HI HI
No
change
D (data) Type
Flip-Flop
A bistable device with two inputs
and two outputs (either or both
outputs may be used). When trig­
gered the state of the "1" output
changes to the state at the data (D)
input prior to the trigger. The out­
puts are complementary (i.e., when
one output is HI the other is LO).
The edge symbol on the trigger (T)
input may be of either polarity,
depending on the device.
Input / Output
A
X X
LO LO
HI
HI
HI LO
Output conditions shown
after trigger pulse
Triggered Set
Clear
(J-K)
Flip-Flop
A bistable device with three or
more inputs and two outputs
(either or both outputs may be
used). When triggered, the outputs
change state in response to the
states at the inputs prior to the
trigger. The outputs are
complementary (i.e., when one
output is HI the other is LO). The
edge symbol on the trigger (T)
input may be of either polarity
depending on the device.
Input / Output
A B
X I X
LO LO No change
LO HI LO
HI
HI LO HI LO
HI HI Changes
state
Output conditions shown
after trigger pulse
Flip flop with
direct inputs
(may be applied
to all triggered
flip-flops)
For devices with direct-set
(S
q
)
or
direct-clear
(C
q
)
inputs, the indi­
cated state at either of these inputs
over-rides all other inputs (including
trigger) to set the outputs to the
states shown in the input/output
table.
Input / Output
A
B
c
D
X X
t 1
LO LO
No
change 1
♦ LO HI LO HI
<t> <t>
HI
LO HI LO
<t>
hl
HI
Unde ­
fined
<t> ■ Has no effect in this
case
' Output state determined
by conditions at triggered
inputs
3-5