I've seen pictures of the back of the PCB, but not the front, so here are some with epoxy removed. This is my Reprint Edition, the latest release, just got it a few weeks ago. The rom itself is an exact match of the Revision B that is already floating around.
Interesting for the first version and the reprint. They had epoxy on everything. I imagine they decided since the game is dumped already there was no point.
[FONT=Verdana, Arial, Helvetica, sans-serif]And here is rev2 (picture found some years ago on emu-land.net boards, courtesy of HardwareMan) [/FONT] Same chips, different design. I heard the new design had issue with model 1 consoles on power-on. I wonder what all those resistors connected to i/o pins on the new board are for ?
It has issues with the Non-TMSS Model 1 systems. You are greeted with a black screen every time you power it on, you must press the reset button after power on for the game to work, each time.
The EPM240 is a 3.3V part and to interface it with 5V signals you are supposed to enable the internal clamp diodes and use an external series resistor. I guess they didn't bother doing that one the original release and just directly connected the bus lines to the CPLD IO. This is something you can generally get away with (although the datasheet doesn't approve of it), but it's possible that it will result in long-term reliability issues.
The EPM240 actually doesn't have clamp diodes, so the resistors serve no purpose but to increase the rise-time. 3.3V-only CPLD may have gate oxide that can endure months of 5V, but they will eventually fail. There's so much bad engineering in homebrew...
Interesting - I had only ever used the EPM1270, and that did have them. Seems like a strange omission from the smaller parts. My guess is that the figured that the 68K would only pull things up to about 3.8V anyway, so it should last long enough...
Sorry for the Necrobump guys, but I am thinking of grabbing a copy of Pier solar and was wondering which revision I should get from a hardware quality/reliability standpoint? I see there are a few differences in the boards shown above, but which is 'better' in the view of people in the know?
y tho? It's gotta be purely academical, because it's not likely you'll be given a chance to pick a board revision when buying?
After having read the "The Dangers of 3.3V Flash in Retro Consoles" article, I wonder if the WM cartridges are handling the voltages properly? Seeing that WM really has an eye for detail I'm sure they did a stellar job, but just curious to know
Just read what Calpis wrote. Meaning nope, they didn't do it properly. It had to be voltage translator ICs instead of resistors, for that specific Altera chip.
As sad as that may sound I once in a while take in MVS Neo Geo units that have been damaged by such carts (bootlegs using 3.3v flash chips) for service. On the Neo Geo the problem is more serious because when the units are used professionally (coin play) they stay a long time powered on, in a daily basis. Usually when it breaks due to this condition (3.3v part sinks current from the 5V part) both the system and the cartridge are damaged.
@l_oliveira If you had an immaculate Wondermega, would you play Pier Solar on it? I am now starting to worry...
Which one would be less harmful to the machine itself? I'm guessing resistors are going to increase the power draw on the bus, whereas no resistors will cook the cart quicker?
The resistors will actually reduce the current flow, reducing or slowing any eventual damage. There's a tendency that the lower voltage device at the input side will sink more current current from the higher voltage device at the output side (higher than what would it be if both devices were running at the same voltage) when the higher voltage device is supplying a high(1) logic level.
Ah right. Thanks. My cart arrived today. It's the Reprint version and it's a rev.3 board with all the little resistors. So all good!
