MMX2/MMX3 MaskROM pinout

MMX2/MMX3 MaskROM pinout
by qwertymodo on 2013-05-29 (#112568)

Does anybody have a confirmed pinout for the MaskROMs used on Cx4 PCB's? I've seen varying pinouts for the surface-mount MaskROMs depending on if they're 8-bit or 16-bit, and I can't seem to find any info on whether MMX2/MMX3 are 8 or 16 bit, or what the pinout is.

Edit: This page seems to indicate the ROM is 16-bit, but from some quick multimeter testing, there's no way that any of these pinouts match what I'm seeing

Re: MMX2/MMX3 MaskROM pinout
by MottZilla on 2013-05-29 (#112574)

The number of pins on the MaskROM would let you know if it's 16bit or not. You can get pretty close by knowing how many address lines, data lines, control signal, and power pins would be needed for the size of ROM you have. Now a 27C160 which supports 16bit is 42 pins and the same size as MMX3. By comparison the 8bit SNES MaskROMs which support atleast up to 32 megabits are 36 pins. I think they actually support up to 64 megabits. Either way, that's for an 8bit memory.

Re: MMX2/MMX3 MaskROM pinout
by qwertymodo on 2013-05-29 (#112578)

Here's the pinout that I traced myself:

Code:

         ____    ____
        |    \__/    |
GND     |01        40|  Vcc
GND     |02        39|  Vcc
Cx4#34  |03        38|  Vcc
GND     |04        37|  GND
Cx4#30  |05        36|  Vcc
Cx4#29  |06        35|  Cx4#27
Cx4#33  |07        34|  Cx4#28
Cx4#37  |08        33|  Cx4#35
Cx4#42  |09        32|  Cx4#36
Cx4#43  |10        31|  Cx4#41
Cx4#44  |11        30|  Cx4#40
Cx4#45  |12        29|  Cx4#38
Cx4#46  |13        28|  Cx4#32
Cx4#47  |14        27|  Cx4#39
Cx4#48  |15        26|  Cx4#52
Cx4#49  |16        25|  Cx4#53
Cx4#60  |17        24|  Cx4#54
Cx4#59  |18        23|  Cx4#55
Cx4#58  |19        22|  Cx4#56
GND     |20        21|  Cx4#57
        |____________|

That actually looks exactly like the GSU MaskROM pinout on the ROM Laboratory page. Derp.