Deep IIci rejuvenation, possible ROM select problem — #13

Post #13 by trag

Source Forum	68kMLA
Category	Hardware
Post Date	Sun, 28 Feb 2010 - 03:46
Original URL	https://68kmla.org/bb/threads/deep-iici-rejuvenation-possible-rom-select-problem.19657/

Post

UPDATE:
Today I solved the problem with my Mac IIci. It is fully-functional off of Built-In ROM. Address Line 16 was damaged UNDERNEATH the battery holder. A battery had exploded on this logic board at one point, and leaked through, making A16 intermittent. It passed a continuity check earlier, but not enough for the data to get through.

Anyone have a clue whether the A17 to pin 42 thing is likely to work? It seems logical to me.

That's great that you were able to fix it. Expanding the addressing as you intend should work in principle, but according to "The Guide to the Macintosh Family Hardware" pin 40 in the ROM socket is A17. Of course, if you started counting the address pins at 1 and the socket pins at 0, then we'd still be talking about the same pins, just with different names.

According to TGTTMFH:

ROM SIMM Socket

Code:

Pin Number     Signal Name
1                          +5V
2                          A0
3                          A1
4                          A2
5                          A3
6                          A4
7                          A5
8                          A6
9                          A7
10                        GND
11                        ROM CS_ 
12                        ROM OE_
13                        +5
14                         D0
15                         D1
16                         D2
17                         D3
18                         D4
19                         D5
20                         D6
21                         D7
22                         D8
23                         D9
24                         D10
25                         D11
26                         D12
27                         D13
28                         D14
29                         D15
30                         GND
31                         A8
32                         A9
33                         A10
34                         A11
35                         A12
36                         A13
37                         A14
38                         A15
39                         A16
40                         A17
41                         A18
42                         A19
43                         A20
44                         A21
45                         A22
46                         +5V
47                         D16
48                         D17
49                         D18
50                         D19
51                         D20
52                         D21
53                         D22
54                         D23
55                         D24
56                         D25
57                         D26
58                         D27
59                         D28
60                         D29
61                         D30
62                         D31
63                         +5V
64                         GND

I'm finally posting from home, so my books are available.