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The next lower three addres:s 1 t'nes' (A12~ All~ Ala) are decoded
by.
two each
'74LS42, U5and U6,
U5 is strobed bY'
S.X"~
ltne and
select~
the lower
8
addres:s
banks.
u6
is strobed by
Sy*
line a~d sel~cts the upper
8
addres~ 6ank~,
U5 and U6 are designated Chi'p Select Decoders on the s:chematt'c dt'agram,
CHIP 5ELECr
DECODER~
AI\
AIO
@-'---";:+--
SKlf
Each chtp enable 1 ine goes to ptn
8
(cE~'~l
of a
patr
of 2114L
chi'ps~p
(1 K block)
The lower ten address 1 ines are used for dlrect address lng of the 1 K chi'p pat rs,
and are buffered bY' U3 and U7.
4
o
o
o
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