May 2014
Intermediate to advanced
320 pages
13h 41m
English
Content preview from Servicing Personal Computers, 3rd Edition
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40 Servicing Personal Computers
NCC
A12C
A7C
A6C
A5C
A4C
A3C
A2C
Aid
AOC
DOC
DIE
D2C
0VÇ
1·
W
28
14 15
3+5V
H
WE
3CS2
DA8
JA9
HAH
HOE
H
AIO
Des
UD7
H D6
3 D5
HD4
HD3
Figure 1.42. 6246 pin connections
Table 1.5 Truth table for the control inputs of a 6264 RAM
WE
X
X
1
1
0
0
cs
1
X
0
0
0
0
CS2
X
0
1
1
1
1
OE
X
X
1
0
1
0
Mode
Not selected
Not selected
Output disabled
Read
Write cycle 1
Write cycle 2
Data line state
High impedance
High impedance
High impedance
Data out
Data in
Data in
A typical 64K memory using eight 6246 devices is shown in Figure 1.43. Thirteen address
lines (A0 to A12) are common to each 6264 whereas the three most significan ...