From (S29Al004D70Tfi010) - Olivetti ECR 7900 Service Manual

3-13-2. FROM (S29AL004D70TFI010)

512K bytes FROM is used as programming.
P00 through P07 are multiplex bus that consists of data bus (D0-D7).
P20 through P27 are multiplex bus that consists of data bus (A0-A7).
P30 through P37 are multiplex bus that consists of data bus (A8-A15).
P40 is multiplex bus that consists of data bus (A16).
P41 is multiplex bus that consists of data bus (A17).
P42 is multiplex bus that consists of data bus (A18)
P43 is multiplex bus that consists of data bus (A19)
P47 is used for chip select at RAM.
P52 is used for Output Enable, P50 is used for Write Enable control.
EXTERNAL MEMORY CIRCUIT
*10 0pF
40
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
WR#
RD#
RO M_CS#
C7 0
RE SET#
ECR 7900 Service Manual
U2
45
D15/A-1
25
A0
24
A1
23
A2
22
A3
21
A4
20
A5
19
A6
18
A7
8
A8
7
A9 D10
6
A10 D11
5
A11 D12
4
A12 D13
3
A13 D14
2
A14
1
A15 RY /BY
48
A16
17
A17
16
A18
9
NC
10
NC
13
NC VCC
11
WE
28
OE VSS
26
CE VSS
12
RESET BY TE
S29 AL00 4D70 TFI0 10
D0
29
D0
D1
31
D1
D2
33
D2
D3
35
D3
D4
38
D4
D5
40
D5
D6
42
D6
D7
44
D7
30
D8
32 VBB
D9
34
36
R9 2
39
10K
41
43
FRDY
15
14
NC
VBB
37
C1 7
C1 11
*0.0 1uF 0.1 uF
27
46
R9 5
47
10K
Y108540-8