Circuit Description - Sharp PC-1500 Service Manual

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4. CIRCUIT DESCRIPTION
1
4-1 . . Chip Select Circuit
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p
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I/o
p
0
DM£1
DllEO
R
T MEO
MEI
ADS
TC40Hl89F
TC40Hl·38F
VGG
so
To RAMS ( TC551? AF)
S I
52
Tu
MOOJle Unil
sa
S7
Y4
Y5
Vss
Vss
n
SG
vee
WEX
Th 1/0 Port
V2
To OiSpl ay chip 1.3
L......f---Q=va
To Display <;l1ip2.4
' -- - -- - - -- + To RAllj ,
2( TC,:~~14r)
' -- -- - -- - - - -- - - - - -- -+ To VO PORT( LH5810)
'--+To R0ll(CS613 128F)
' -- -- - - -- - - -- - -- - - --•To MOOul lhi t
' - -- -- - - -- - -- -- - - - - - - + T o Mcdvl lhit
tt.tou1i•
Internal logic
Truth Table
VO
A
Input
ENA .BL!
Sl>L1$CT
Output
Vi
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H L L II L II II II
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II II L II H
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L
H II II II H II II H L H
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