Tektronix OPTION 10 Service Supplement Manual page 8

464 and 466 Opt ion 1 0
Figure Opt ion 1 0-3 cont ains t hree cat egories of dat a , as
follows .
Figure Opt ion 1 0-3
shows t he logic cont ent of t he
m em ory cells in U3605 . A " 1" indicat es a high - logic level .
The digit s wit hin t he heavy - lined border represent t he 1 024
m em ory cells .
1 . The colum n of dat a at t he left end represent s t he
input t o ROM U3605 . It is called " present" dat a .
Dat a in t he colum n at t he left side of Figure Opt ion 1 0-3
represent s t he input s t o U3605 from t he A TIME/ DIV con
t rol and t he VERT MODE cont rol . The input from t he A
TIME/ DIV cont rol indicat es whet her it is in X Y posit ion .
The dat a in t his colum n is considered " present " dat a .
2. The eight colum n headings wit hin t he heavy - lined
border represent t he logic levels on t he t hree feed
back lines from U4705 t o U3605 . These t hree logic
levels are " past " dat a relat ing t o t he oscilloscope's
m ode of operat ion .
The headings for t he eight colum ns of ROM dat a repre
sent t he eight possible com binat ions of logic levels on
t he t hree feedback lines from U3705 t o U3605 . ( Only four
of t hese com binat ions are used in t he Opt ion 1 0 osci llo
scope . ) The levels on t he feedback lines represent " past "
dat a because t he feedback lines act ivat e t he gat e- drive
t ransist ors .
3. The four - bit binary num bers wit hin t he heavy - lined
border represent t he logic levels on t he ROM's four
out put lines . These num bers are dat a relat ing t o t he
next m ode of operat ion - t he m ode t he oscilloscope
will t ake aft er t he next clock pulse occurs . These
num bers represent " fut ure " dat a .
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