2Mbyte RAM? Nintendo hasn't used such large RAMs in any SNES cartridges. Biggest should be 128K in a few games, and 512K in Satellaview BIOS (not SA-1 related, it's just the biggest RAM size they have used).
I have scribbled down SA-1 pinouts a while ago, too (but didn't have released them yet).
The cartridge I had borrowed is Kirby's Fun Pak (PAL) "SNSP-1L3B-20" with 28pin 8Kbyte SRAM.
According to the "3B" in the PCB name, 8Kbyte (A0..A12) would be max size for that board, but A13,A14 are also connected on the 28pin chip, and there are even solder-pads for 32pin SRAMs, which seem to connect A15,A16,A18. And A17, on a 32pin chip, A17 should replace Vbat (on a 28pin chip), there are actually solder pads for replacing that pin (though my original conclusion was that it replaces Vbat by CS, which was probably wrong).
Anyways, SA-1 pin-outs as far as I could tell:
Code:
1 SNES./IRQ
2 SNES.D7
3 SNES.D3
4 SNES.D6
5 SNES.D2
6 SNES.D5
7 SNES.D1
8 SNES.D4
9 SNES.D0
10 VCC
11 GND
12 SNES.A23
13 SNES.A0
14 SNES.A22
15 SNES.A1
16 SNES.A21
17 SNES.A2
18 SNES.A20
19 SNES.A3
20 SNES.A19
21 SNES.A4
22 SNES.A18
23 SNES.A5
24 SNES.A17
25 SNES.A6
26 SNES.A16
27 SNES.A7
28 SNES.A15
29 SNES.A8
30 SNES.A14
31 SNES.A9
32 SNES.A13
33 SNES.A10
34 SNES.A12
35 SNES.A11
36 VCC
37 GND
38 REFRESH
---
39 GND
40 X.?
41 X.?
42 GND
43 ROM.D15 pin31 (D15/A0)
44 ROM.D7 pin30
45 ROM.D14 pin29
46 ROM.D6 pin28
47 ROM.D11 pin22
48 ROM.D3 pin21
49 ROM.D10 pin20
50 ROM.D2 pin19
51 ROM.D13 pin27
52 ROM.D5 pin26
53 ROM.D12 pin25
54 ROM.D4 pin24
55 ROM.D9 pin18
56 ROM.D1 pin17
57 ROM.D8 pin16
58 ROM.D0 pin15
59 ROM.A1 pin11
60 ROM.A2 pin10
61 ROM.A3 pin9
62 ROM.A4 pin8
63 ROM.A5 pin7
64 ROM.A6 pin6
---
65 ROM.A7 pin5
66 ROM.A8 pin4
67 ROM.A9 pin42
68 ROM.A10 pin41
69 ROM.A11 pin40
70 ROM.A12 pin39
71 ROM.A13 pin38
72 ROM.A14 pin37
73 ROM.A15 pin36
74 ROM.A16 pin35
75 ROM.A17 pin34
76 ROM.A19 pin2
77 ROM.A18 pin3
78 ROM.A20 pin43
79 ROM.A21 pin44
80 ROM.A22 pin1
81 maybe A23 ?
82 GND?
83 VCC
84 GND
85 GND?
86 SRAM. A16? pin1-1 (extra pin)
87 SRAM. A14 pin1
88 SRAM. A12 pin2
89 SRAM.A7 pin3
90 SRAM.A6 pin4
91 SRAM.A5 pin5
92 SRAM.A4 pin6
93 SRAM.A3 pin7
94 SRAM.A2 pin8
95 SRAM.A1 pin9
96 SRAM.A0 pin10
97 SRAM. A10 pin21
98 SRAM. A11 pin23
99 SRAM. A9 pin24
100 GND
101 VCC
102 SRAM. A8 pin25
---
103 to left-solder pads (U4.3.CS) (aka SRAM.A13)
104 SRAM. A18?? pin1-2 (extra pin)
105 SRAM. A15 pin28+1 (extra pin)
106
107
108 SRAM. /OE pin22
109 SRAM. /WE pin27
110 SRAM.D0 pin11
111 SRAM.D1 pin12
112 SRAM.D2 pin13
113 SRAM.D3 pin15
114 SRAM.D4 pin16
115 SRAM.D5 pin17
116 SRAM.D6 pin18
117 SRAM.D7 pin19
118 GND
119 VCC
120 SNES./RESET
121 SNES.SYSCK
122 SNES.CIC3 (3.072MHz)
123 SNES.CIC2
124 SNES.CIC1
125 SNES.CIC0
126 SNES./WR
127 PAL/NTSC (GND=NTSC, VCC=PAL) (for CIC mode and/or HV-timer?)
128 SNES./RD
ROM-Chip Note: ROM./CE and ROM./OE are wired to GND (always enabled).
ROM-Chip Note: ROM.BHE is wired to VCC (always 16bit databus mode).
U4.Pin5./CS ---> SRAM./CS pin20 (U4:6129A aka PCB:MM1026AF)
U4.Pin3.CS ---> SRAM.A13? pin26
(left 4 solder-pads near U4 --> SRAM.pin26 = CS or A14)
(right 4 solder-pads near U4 --> SRAM.pin28 = CS or Vbat)
Cart Slot Unused: /ROMSEL
Cart Slot Used: SHIELD (!)