[Solved] Help with Aladdin repro
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1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.
[Solved] Help with Aladdin repro
Hello.
I tried to fix a snes dead epoxy pcb that was on a case with the Aladdin's label.
I used 2 4mbit flash ROMs stacked over a 2mbit one.
To decode the addresses I used half of a 74HC139, plugged A19 on A, A20 on B, the /E pin on /CART, Y0 to the 1st 4mbit ROM /OE, Y1 to the 2nd 4 mbit ROM /OE and Y2 to the /OE pin of the 2 mbit ROM.
The /RD pin is plugged into the ROMs /CE.
All the other pins are plugged together to their respective data/adress bus pins, but I just get a black screen.
I've tested it exaustivelly but couldn't find the error.
Could it be the address decoding that I'm doing wrong? If so, how can I fix it?
An interesting thing is that if I put the board on a gamegenie I also get a black screen, shouldn't the gamegenie code screen appear?
Thanks in advance.
I tried to fix a snes dead epoxy pcb that was on a case with the Aladdin's label.
I used 2 4mbit flash ROMs stacked over a 2mbit one.
To decode the addresses I used half of a 74HC139, plugged A19 on A, A20 on B, the /E pin on /CART, Y0 to the 1st 4mbit ROM /OE, Y1 to the 2nd 4 mbit ROM /OE and Y2 to the /OE pin of the 2 mbit ROM.
The /RD pin is plugged into the ROMs /CE.
All the other pins are plugged together to their respective data/adress bus pins, but I just get a black screen.
I've tested it exaustivelly but couldn't find the error.
Could it be the address decoding that I'm doing wrong? If so, how can I fix it?
An interesting thing is that if I put the board on a gamegenie I also get a black screen, shouldn't the gamegenie code screen appear?
Thanks in advance.
Last edited by Fisher on Sun Jul 19, 2020 3:58 pm, edited 1 time in total.
Re: Help with Aladdin repro
There's nothing obviously wrong with what you've done. You could try programming my memory map displayer onto the first ROM.
- poorstudenthobbyist
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Re: Help with Aladdin repro
If you're getting a black screen, even with the Game Genie, maybe there's a bus conflict somewhere? Is it wired correctly, and are the old ROM chips disabled?
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Re: Help with Aladdin repro
Thanks for the software @linariq.
I'll try to put it there to test.
Would be possible to hack a game genie rom to add this kind of functionality?
It would be a great way to debug the thrash I try to transform into cartridges.
Yes, @poorstudenthobbist, initially I was suspecting it could be a short circuit somewhere, but I couldn't find it.
Maybe it's related to the 74'139, since it was got from a junk pile and I couldn't test it because it's an smd part.
Could decoupling be an issue?
The stacked memories are plcc32 and the demux is on top of them.
I tried to put 2x 10uf electrolytic capacitors on the pcb, but I didn't see any improvement.
I'll try to put it there to test.
Would be possible to hack a game genie rom to add this kind of functionality?
It would be a great way to debug the thrash I try to transform into cartridges.

Yes, @poorstudenthobbist, initially I was suspecting it could be a short circuit somewhere, but I couldn't find it.
Maybe it's related to the 74'139, since it was got from a junk pile and I couldn't test it because it's an smd part.
Could decoupling be an issue?
The stacked memories are plcc32 and the demux is on top of them.
I tried to put 2x 10uf electrolytic capacitors on the pcb, but I didn't see any improvement.
Re: Help with Aladdin repro
As a test, I unplugged the /cart pin from the demux and had plugged it on the /oe of the first 4mbit rom.
I also plugged the demux /e pin to vcc.
I've got a black screen again.
On a emulator I've got a screen with garbled characters and them a black screen if I load the 1st 4mbit only.
I also tried a led plugged on vcc and /cart.
It blinked so fast it seemed to have half bright for about a second them became full bright.
I'll do some more tests with what I have here, but I think this discards a bad demux and points to something else, does it?
I also plugged the demux /e pin to vcc.
I've got a black screen again.
On a emulator I've got a screen with garbled characters and them a black screen if I load the 1st 4mbit only.
I also tried a led plugged on vcc and /cart.
It blinked so fast it seemed to have half bright for about a second them became full bright.
I'll do some more tests with what I have here, but I think this discards a bad demux and points to something else, does it?
Re: Help with Aladdin repro
Aladdin is LoROM. When you said A18 and A19, I assume you meant SNESA19 and A20, because SNESA15 isn't connected to anything?
Not that I think that's sufficient to explain what's going on here.
Not that I think that's sufficient to explain what's going on here.
Re: Help with Aladdin repro
Yes, I skipped SNES A15.
The LED on the Y0 output stood with full bright.
I think I'll try to change the demux and see what will happen.
I need to take a nice picture and post here, but I just can't do it on my crappy phone.
The LED on the Y0 output stood with full bright.
I think I'll try to change the demux and see what will happen.
I need to take a nice picture and post here, but I just can't do it on my crappy phone.

Re: Help with Aladdin repro
Hey Lidnariq, is it possible to hotswap your program?
If so it would be possible to write it to a test cart, hotswap with the repro and them take a good look on what is being read from the ROM.
I already exchanged the demux twice with the same results.
The most thing I could do is to make the bottom half of the screen flash in red, wich is very weird!
If so it would be possible to write it to a test cart, hotswap with the repro and them take a good look on what is being read from the ROM.
I already exchanged the demux twice with the same results.
The most thing I could do is to make the bottom half of the screen flash in red, wich is very weird!
Re: Help with Aladdin repro
That's a simple and nice tool!
Thanks for sharing.
I tried hotswapping it with some known good games and they have shown the data.
Unfortunately, when I plug the Aladdin cart the console crashes.
I even tried to bypass and disable the demux and got the same results.
I think it probably means I have some wiring issues...
Any tips on where/what I should start looking?
Thanks for sharing.
I tried hotswapping it with some known good games and they have shown the data.
Unfortunately, when I plug the Aladdin cart the console crashes.
I even tried to bypass and disable the demux and got the same results.
I think it probably means I have some wiring issues...
Any tips on where/what I should start looking?
Re: Help with Aladdin repro
For now, what happens if you disable the 74'139 altogether, so that the ROMs are theoretically all disabled?
Re: Help with Aladdin repro
I removed the wire to the /E pin and left it floating, them I soldered the IC's /E pin to vcc.
The memories should be all disabled with this, but I got the same results.
Is just me who's finding it very weird?
The memories should be all disabled with this, but I got the same results.
Is just me who's finding it very weird?
Re: Help with Aladdin repro
What's the resistance from +5V to ground?
... actually, given the SNES cartridge pinout ... no chance you have +5V and ground backwards, right?
... actually, given the SNES cartridge pinout ... no chance you have +5V and ground backwards, right?
Re: Help with Aladdin repro
It was weird.
Measuring even with the correct or the inverted polarity I started reading 500K and then it started growing.
After I removed the capacitors of the board, I've read 4,8M with the correct polarity and 1,06M with it inverted.
It was corrected, but I may be misreading the pinouts.
Measuring even with the correct or the inverted polarity I started reading 500K and then it started growing.
After I removed the capacitors of the board, I've read 4,8M with the correct polarity and 1,06M with it inverted.
That was one of the first things I checked.
It was corrected, but I may be misreading the pinouts.
Re: Help with Aladdin repro
Is the original chip-on-board still there? Is there any chance it's interfering with things?
Are any of the address, data, or control lines low-ish resistance to ground or +5v?
Are any of the address, data, or control lines low-ish resistance to ground or +5v?