PROPHET64 & MSSIAH Userforum

There is a simple solution.
You can build a switch that interrupts 2 pins of the cart-port.
You can find more info on this page.

I made the modding! I the P64 ULTIMAX!?  BECAUSE IT'S NOT WORKING!

Everything is correct, in fact my GORF cartridge works when the 2 switches ar UP and when they're DOWN I get the BASIC prompt...

But with P64 it's different, I get the BASIC prompt ANYWAY! WHY? maybe it's ULTIMAX?? Maybe the switches have too hign impendence?

Hope to find a way to make this modding work...

http://www.koney.org/files/switch2_c64.JPG
http://www.koney.org/files/SWITCHc64.JPG

I'm testing the mod in a second commodore before fitting it it the SID2SID one.

I used 2 switches because I didn't find a 2way switch in the shop so I took 2 one way...

HEHE I had it since ages...good as a testing cart.

GORF work, P64 doesnt'...WHY? I just brigdet two pins with a switch...

I'll try by joining the contacts togheter again...

Anyone has a cloue?

I did. I meant "BRIGDE THE CONNECTIONS OF TWO PINS" not that I joined them

Up position of both switches means that the thirs and unused connection of the pic should be...shorted? to pin 22? (I guess..ground?)

The point is: when the switches are ON there's virtually no change in the ecectronics, but the P64 don't start anymore...

Jaicen wrote:

In answer to your question, if you have the type of switch which has three positions with the center off (up/off/down), then yes the up position of both switches needs to connect to pin 22. If your switch only has two positions (up/down), then you won't be able to do this.

Why not? Shouldn't it be an on/off operation? What would the third position do?
If the mod works, I'd use a two way switch with two connectors (DPDT). Perhaps someone could shed some light in why this isn't working. It would be great to be able to boot your c64 to normal blue screen without having to pull out the P64 cart. I have a fealing that after some time the connection surface of the cart will ware out...

You need the on/off/on operation if you want both types of cartridge bypass. If you wire the up position to pin 22, you have only two options: Ultimax Bypass, and Cartridge on, you don't have the option to disconnect the pins from the PCB. Does that make sense?

So you're saying that the switch no-longer allows the cartridge to boot?
If other cartridges boot, then I'd try the prophet cart in another machine to make sure you haven't damaged it accidentally (ie, by soldering with it still connected!). If it works in other machines, it's possible that one of your switches is faulty (ie, only connecting one pin to the PCB). In that case, you should check for shorts or dodgy wiring/soldering.

Jaicen wrote:

http://img45.imageshack.us/img45/2452/diagramyl9.jpg

Errr... shouldn't the PCB wires be connected to the middle pins of the switch?
You aren't making much sense by shorting pin 22 with the cart, are you?

On Markus Brenner's website you can read that position 3 needs to connect the PCB lines 'game' and 'exrom' to GND, which is the Ultimax setting.

[edit]
If I understand mr. Brenner correctly, it should be something like this:

Last edited by AxiMaxi (2006-07-23 23:23:56)

Actually it makes perfect sense to short to pin 22, since that pin is grounded.
From Markus' site:
Inbetween each pair of wires goes your switch:


- Position 1 (ON) of the switch needs to connect cartridge port and PCB to
  the normal connection. This is your standard mode to play the games.

- Position 2 (OFF) leaves both PCB pins unconnected, like if no cartridge is
  inserted.

- Position 3 (ON) connects the PCB GAME and EXROM lines to GND. This
  configuration is used to dump 'ULTIMAX' mode cartridges.

The only way this can be achieved, is if the pins from the cartidge port are toggled between GND/off/PCB.
Of course, if you're only using an ON/ON two way switch it doesn't make a blind bit of difference what you wire, as long as you wire the right pins, but you won't be able to have the ULTIMAX mode without an on/off/on switch.

I actually just had a thought about the way that the Prophet64 cart is actually constructed. If it uses a PROM chip, it might not have pin 8 connected, so disabling that won't work. If it's built like many of the homebrew EPROM units i've seen, you can disable the chip by simply grounding pin9.
Has anybody seen inside the cart or know anything about this?

Sorry for repeat my question again, but is there an address to poke to check if the cartridge is there even if it didn't boot? That can be a good troubleshoot...

Jaicen wrote:

- Position 1 (ON) of the switch needs to connect cartridge port and PCB to
  the normal connection. This is your standard mode to play the games.

- Position 2 (OFF) leaves both PCB pins unconnected, like if no cartridge is
  inserted.

- Position 3 (ON) connects the PCB GAME and EXROM lines to GND. This
  configuration is used to dump 'ULTIMAX' mode cartridges.

Markus clearly makes a difference between cartridge port and PCB.
And in position 3 he says 'connect PCB ... to GND', which I read as: connect the GND to the PCB pins, not the cart pins.
And the picture on his website, looks like what I have drawn, although it's not clear which side of the pins is cart and which is pcb.

[edit]
The page also reads:
By using 'ULTIMAX dumping mode' you pull both the GAME and EXROM lines to GROUND instead of restoring the original cartridge configuration. This way you trick the computer into believing it is using standard 16kB cartridge mode, ...

So you need to trick the computer, not the cartridge.
Again, it doesn't make sense to GND the cart lines, you need to GND the PCB lines.
Which is quite logical too: normally the cartridge would do so, now you bypass it with a switch.

Last edited by AxiMaxi (2006-07-24 13:05:57)