External Memory; Sram (Bs62Lv4006Scp-70) - Olivetti ECR 7900 Service Manual

3-13. EXTERNAL MEMORY

3-13-1. SRAM (BS62LV4006SCP-70)

512K bytes S-RAM used as an external RAM for PLU and Electric Journal and etc.
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).
P45 is used for chip select at RAM.
P52 is used for Output Enable, P50 is used for Write Enable control.
EXTERNAL MEMORY CIRCUIT
RA MCS #
WR#
RD#
38
U3
A0
12
A0
A1
11
A1
A2
10
A2
A3
9
A3
A4
8
A4
A5
7
A5
A6
6
A6
A7
5
A7
A8
27
A8
A9
26
A9
A10
23
A10
A11
25
A11
A12
4
A12
A13
28
A13
A14
3
A14
A15
31
A15
A16
2
A16
A17
30
A17/CE2
A18
1
A18/A17
22
CE
29
WE
24
OE
BS 62LV4 006S CP-7 0
C7 3
*10 0pF
ECR 7900 Service Manual
D0
13
D0
D1
14
D1
D2
15
D2
D3
17
D3
D4
18
D4
D5
19
D5
D6
20
D6
D7
21
D7
VBB
C1 9
32
VCC
C7 9
*0.0 1uF
16
GND
0.1 uF
Y108540-8