HELP! Bank Error and ROM Cartridge error

Pedrobear

Cheng's Errand Boy
Joined
Mar 1, 2012
Posts
113
Also, how capable is your oscilloscope?
Can you monitor D0/D1 status when portwel goes low?
 
Joined
Apr 5, 2017
Posts
33
Did you see the signal shape? Is it decent enough (square angles) or rubbish?


Ok, let's check up banking with unibios.

Use samsho4 and go to ingame menu during neo geo splash screen.

Use patch memory function to bank, write 00/01/02/03 to 2fffff to switch between banks 0/1/2/3. (portwel will go low to latch data)

Manually select a bank via patching then go to memory viewer, and go check address 2ffff0. Hold D to go through faster. It should read 000X (8 times), where X is the bank # you patched in.

Patch in a few bank changes then check the memory value, tell us what's showing up. (not the correct # I guess but meh, let's see exactly)

It went low, then went high (was a flash like you nano seconds). I posted a picture, it shows the last 3 banks identical crcs. This implies its not changing right? I'll update when I've done this.
 

Pedrobear

Cheng's Errand Boy
Joined
Mar 1, 2012
Posts
113
Quality (shape) of the signal could possibly affect logic gates behavior. That's why I ask is signal is nice and square.

Yep, obviously the bank is struck, thing is, different games are struck to a different bank so that's strange. MSX has different hardware tho.

Try multiple writes maybe, see if that's a total no go or unstable thing.
 

GadgetUK

Ace Ghost Pilot
Joined
Sep 27, 2013
Posts
1,323
I like your technique there of using the sam sho cart with a memory patch to invoke a banking switch =D
 

Pedrobear

Cheng's Errand Boy
Joined
Mar 1, 2012
Posts
113
You aren"t pressing simultaneously. :)

Hold select + start from unibios splash screen.
 

Pedrobear

Cheng's Errand Boy
Joined
Mar 1, 2012
Posts
113
Hmm, really weird but let's work around it.

Put a working game in slot 1, samsho4 in slot2.

Boot slot 1 game, go to ingame menu.
Patch 0x01 to 0x380021. This will switch to slot 2. (verify by looking up for 0x0222 at ram address 0x108)

Resume tests from there.
 

Burgers5750

Kabuki Klasher
Joined
Jan 7, 2017
Posts
127
Here is a final check list of all I've done:
* Flashed to Unibios and checked the roms, see above pictures
* Cleaned the carts and edge connectors real well (contact cleaner)
* Cleaned the board to board connectors
* Verified voltage @ the harness and PS
* Verified cartridges worked on another Neo Geo.
* Checked internal battery
* Cleared work ram.

I'm waiting on replacement cartridges to test those. In the mean time, does ANYONE have any ideas? thank you.

What a drama you're having.

Sounds stupid but have you opened the carts to check the boards are facing the right way around?

I never insert a new cart into my MVS without cleaning it first anyway. I don't want any dirt etc. going into the cart slot from dirty contacts. Then I do a CRC check via Unibios and will occasionally get errors come up but by removing and reinserting it normally clears this.

If not open the cart again, sometimes a little jiggle straightens up the contacts and away you go. LIttle help I know but eager to see how this resolves itself mate.
 
Joined
Apr 5, 2017
Posts
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What a drama you're having.

Sounds stupid but have you opened the carts to check the boards are facing the right way around?

I never insert a new cart into my MVS without cleaning it first anyway. I don't want any dirt etc. going into the cart slot from dirty contacts. Then I do a CRC check via Unibios and will occasionally get errors come up but by removing and reinserting it normally clears this.

If not open the cart again, sometimes a little jiggle straightens up the contacts and away you go. LIttle help I know but eager to see how this resolves itself mate.

Cartridges work fine on another system. So yeah they are facing the right way. This system is pissing me off!!!

I have had the cards out of the casing and it still does it.
 
Last edited:
Joined
Apr 5, 2017
Posts
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So I recently bought a more capable oscope. I also bought a salae logic analyzer. Lets go over this again, what should I be checking?
 
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