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ROM SIMM Pin Out for SE/30 and Mac II Family
Posted by: trag on 2010-02-27 19:53:34
As long as I was posting it in a different thread, I figured I'd give it its own thread:

According to TGTTMFH:

ROM SIMM Socket

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
Posted by: Dennis Nedry on 2010-03-01 14:30:48
Added to wiki with due credit.
Posted by: Trash80toHP_Mini on 2010-03-01 15:39:36
😛 That's GttMFH: Second Edition! 😉 😱)

IOW: Guide to the Macintosh Family Hardware: Second Edition for those comrades unfamiliar with actual, real life, printed on paper based storage media, that's bound into volumes . . .

. . . and sold for $ in stores. 8-o

Back in the day, some of it was actuaily included (at no charge!) with the software media, shrink wrapped in cardboard boxes and everything! 😱)

PDFs suck . . . unless you actually print them out . . . }🙂

Posted by: trag on 2010-03-02 10:21:56
And we should note, for those who might try to use this information, that A0 and A1 are not connected to the address pins on the ROM chips on the module. A2 of the ROM SIMM connects to A0 on the ROM (or Flash) chips. However, this may vary a bit on the SE/30 and one earlier machine. I need to go check the book again darn it. The concept is that the ROM SIMM is 4 bytes wide and A0 and A1 would be for addressing individual bytes of the word. In other words the ROM SIMM address pins are numbered for byte-wise addressing, while in practice the ROM SIMM is wired for word addressing (four bytes per address).
Posted by: Trash80toHP_Mini on 2010-03-02 11:03:52
In other words the ROM SIMM address pins are numbered for byte-wise addressing, while in practice the ROM SIMM is wired for word addressing (four bytes per address).
How would that affect addressing the ROM slot for using a memory expansion card in a VM scheme?

I've been looking at the Portable ROM slot's 8 MB of burst mode addressable memory space as a great spot to stick some VM hacked SRAM on a card, There's also a nice additional chunk of memory space "reserved for Apple" . . .

. . . that I'm fairly certain they've no longer got any serious plans to use! }🙂

By the way, have you also got a copy of DCaDftMFH? :?:

I had to special order my copy back in the day! 😉

}🙂 :rambo: 😀 😉 😱)

Posted by: trag on 2010-03-02 16:31:34
In other words the ROM SIMM address pins are numbered for byte-wise addressing, while in practice the ROM SIMM is wired for word addressing (four bytes per address).
How would that affect addressing the ROM slot for using a memory expansion card in a VM scheme?
The only effect it has is that you can only address the ROM on word boundaries. Since the ROM is full of code anyway, you wouldn't want to address it any other way. If you plugged some other card in there, presumably it would be a custom card, so if you need to be able to address off word boundaries for your application, then you can hook that function up to A0 and A1 which are available in the ROM SIMM slot as listed. They're just not used on a ROM SIMM. But they're there in the slot.

I don't know whether a VM memory expansion scheme would need off-word-boundary addressing or not.

I've been looking at the Portable ROM slot's 8 MB of burst mode addressable memory space as a great spot to stick some VM hacked SRAM on a card, There's also a nice additional chunk of memory space "reserved for Apple" . . .. . . that I'm fairly certain they've no longer got any serious plans to use! }🙂

By the way, have you also got a copy of DCaDftMFH? :?:

I had to special order my copy back in the day! 😉

}🙂 :rambo: 😀 😉 😱)
The Portable also has a bunch of space available for "Custom ROMs" and a slot to install such a thing in. All kinds of potential for the portable.

Yes, I have DCaDftMFH. I think I got it through Amazon a few years ago. Reading it taught me two things. 1) I need a greater familiarity with "Inside Macintosh". 2) I need to learn (at least rudimentary) Pascal to understand the (presumably helpful) examples.

The Portable has never interested me in and of itself. The thing I find interesting about it is that it has 8 MB of address space allocated for RAM. I have several Outbound Model 125 Laptops and amongst other modifications I'd like to make to them, I'd like to change the memory map so that they can use 8 MB of memory. They have eight SIMM sockets inside, but four of them are dedicated to a RAM disk. Happily, the RAM disk sockets recognize 4 MB SIMMs so one can have a 16 MB RAM Disk which is huge on a Mac Plus equivalent (but 2X clock) machine.
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