What's new

yavuzg

Professional
Joined
Aug 25, 2015
Messages
316
Reaction score
419
Location
Turkey
So as promised I have finished the pinout of a CPS3 32/128Mb SIMM PCB. Again, for reference I took a photo of the SIMM and numbered the flash ICs accordingly since there is no "official" numbering on the silkscreen of the PCB.

Anyway, the 128 Mbit SIMM has 8 x 16Mbit Fujitsu flash ICs. 4 x Normal pinout and 4 x Reverse pinout. The normal pinout ICs are of type MBM29F016-90PFTN and the reverse pinout ICs are of type MBM29F016-90PFTR



IMG_8923_numbered_zpswnsi5xar.jpg



Front:
IC1: Reverse pinout
IC2: Normal pinout
IC3: Reverse pinout
IC4: Normal pinout

Back:
IC5: Normal pinout
IC6: Reverse pinout
IC7: Normal pinout
IC8: Reverse pinout

The 32 Mbit SIMMs I have only IC1 and IC6 populated. Yes, I know the 32Mbit SIMM picture on the CPS3 - Wiki on the "Arcade Otaku Wiki" is somehow different. It might be from early CPS3 production or from late CPS2 (all-in-one black boards) production.

Here is the pinout of the 32/128Mbit SIMM PCB;

PinConn.Note
1VccCommon
2VccCommon
3D7IC1, IC2, IC3, IC4
4N.C.
5D6IC1, IC2, IC3, IC4
6N.C.
7D5IC1, IC2, IC3, IC4
8N.C.
9D4IC1, IC2, IC3, IC4
10N.C.
11GNDCommon
12D3IC1, IC2, IC3, IC4
13N.C.
14D2IC1, IC2, IC3, IC4
15N.C.
16D1IC1, IC2, IC3, IC4
17N.C.
18D0IC1, IC2, IC3, IC4
19N.C.
20GNDCommon
21D7IC5, IC6, IC7, IC8
22N.C.
23D6IC5, IC6, IC7, IC8
24N.C.
25D5IC5, IC6, IC7, IC8
26N.C.
27D4IC5, IC6, IC7, IC8
28N.C.
29GNDCommon
30D3IC5, IC6, IC7, IC8
31N.C.
32D2IC5, IC6, IC7, IC8
33N.C.
34D1IC5, IC6, IC7, IC8
35N.C.
36D0IC5, IC6, IC7, IC8
37N.C.
38N.C.
39A20Common
40A19Common
41A18Common
42A17Common
43A16Common
44A15Common
45A14Common
46A13Common
47A12Common
48A11Common
49GNDCommon
50A10Common
51A9Common
52A8Common
53A7Common
54A6Common
55A5Common
56A4Common
57A3Common
58A2Common
59A1Common
60A0Common
61GNDCommon
62/RESETCommon
63GNDCommon
64/CEIC4, IC7
65/CEIC3, IC8
66/CEIC2, IC5
67/CEIC1, IC6
68GNDCommon
69/WECommon
70N.C.
71/OECommon
72N.C.

As you can see it is totally different than the 64Mbit SIMM module. This PCB controls the flash ICs in pairs (4 total /CE signals controlling 8 x flash ICs in pairs) and there are two sets of data bus where on a 64Mbit SIMM all the flash ICs have their data pins connected seperately and there were only one common /CE signal...
 
Last edited:
I'll probably make a new 64Mb batch....
That's great news...

If you have the time and motivation, my humble suggestion would be to re-design the PCB to use only "Normal pinout" flash ICs and get rid of the hard-to-find reverse pinout ones. I know, it was impossible for the 128Mbit SIMM since it has 8 x flash ICs and the pins could not be routed without changing the vertical size of the PCB considerably.

On the other hand, the 64Mbit SIMM PCB "originally" has spare space on the back side which seems to be used for a new design to host 2 x flash ICs. Then the front side of the PCB may have enough space to route the other 2 x flash ICs. This may lead to less product cost and easier sourcing of flash ICs.
 
I'll probably make a new 64Mb batch....
That's great news...
If you have the time and motivation, my humble suggestion would be to re-design the PCB to use only "Normal pinout" flash ICs and get rid of the hard-to-find reverse pinout ones. I know, it was impossible for the 128Mbit SIMM since it has 8 x flash ICs and the pins could not be routed without changing the vertical size of the PCB considerably.

On the other hand, the 64Mbit SIMM PCB "originally" has spare space on the back side which seems to be used for a new design to host 2 x flash ICs. Then the front side of the PCB may have enough space to route the other 2 x flash ICs. This may lead to less product cost and easier sourcing of flash ICs.
I like that...
 
So this is where I’d learnt that is it not possible to convert 32MB to 64MB since actually the pu out is different.
Right
So the new 128MB Simms are made only of Normal pinout chips or both normal and reverse like the original finaly ?
 
Last edited:
it uses both normal and reversed. Google a picture and you will see.
 
Back
Top