How to hack cartridges
Moderator: Moderators
Excellent!hawk wrote: It now works like a charm.
With MegaCart, it is not necessary to have one of these to play existing ROM based games.
However, the 8K hack with nvram chip is an excellent tool to speed up development of new games or utilities.
If the STK12C68 is obtained as a sample, it is really an inexpensive little project.
Mega-Cart: the ultimate cartridge for your Commodore Vic-20
OK, I've named this new nvSRAM hacked cart the "Flexi-Cart".
This case isn't finished yet, but you can see the labels where the switch is fitted. It has a sliding switch screwed inside to the top on the case.
More pictures to follows soon.
This case isn't finished yet, but you can see the labels where the switch is fitted. It has a sliding switch screwed inside to the top on the case.
More pictures to follows soon.
Last edited by hawk on Mon Jun 03, 2013 7:14 am, edited 2 times in total.
The finished product
I've also posted the Flexi-Cart Label file for anyone else who want to use it.
The cart isn't really PAL only, except I couldn't think of anything else to put there.
I've also posted the Flexi-Cart Label file for anyone else who want to use it.
The cart isn't really PAL only, except I couldn't think of anything else to put there.
Last edited by hawk on Mon Jun 03, 2013 7:18 am, edited 3 times in total.
The new Flexi-Cart Label has been uploaded.
- e5frog
- Vic 20 Nerd
- Posts: 551
- Joined: Sat Feb 17, 2007 5:46 pm
- Website: http://channelf.se
- Location: Sweden
- Occupation: Service Engineer
Re: How to hack cartridges
No inspiration here for a while?
I found an image from this thread when looking at cart PCB:s, I made this multi-cart a while a go with all my favorite games from when I was a kid, it's mostly (only) small BASIC games and cartridge is menu driven and simply loads the program from the cart to RAM, I believe I might even have used pucrunch on some file... don't recall.
I used a VIC-1912 Mole Attack cartridge and set it to autostart Mole Attack if I don't hold button "M" (as in Multicart) when starting up. I never got the latch reset part working properly, maybe I'll revisit the project at one time or another.
An inspirational image - you don't see the bird's nest when it's inside the cart.
I found an image from this thread when looking at cart PCB:s, I made this multi-cart a while a go with all my favorite games from when I was a kid, it's mostly (only) small BASIC games and cartridge is menu driven and simply loads the program from the cart to RAM, I believe I might even have used pucrunch on some file... don't recall.
I used a VIC-1912 Mole Attack cartridge and set it to autostart Mole Attack if I don't hold button "M" (as in Multicart) when starting up. I never got the latch reset part working properly, maybe I'll revisit the project at one time or another.
An inspirational image - you don't see the bird's nest when it's inside the cart.
My other interest: http://channelf.se
Re: How to hack cartridges
That picture is kind of beautiful in a way.
It would be interesting if that cartridge ever got out in the wild and was purchased by an unsuspecting collector. I can imagine the long forum posts trying to figure out why an apparently normal Mole Attack cartridge (auto start into Mole Attack) had such modification.
Music I've made with 1980s electronics, synths and other retro-instruments: http://theovoids.bandcamp.com
- e5frog
- Vic 20 Nerd
- Posts: 551
- Joined: Sat Feb 17, 2007 5:46 pm
- Website: http://channelf.se
- Location: Sweden
- Occupation: Service Engineer
Re: How to hack cartridges
I pieced it together with what I have home at the time, I think eslapion gave me a tip about how to add a proper reset circuit to it but I never got to it (at least not yet).
I imagine in a few years if the label on the back disappears, I'd have a hard time remembering how to use it.
I imagine in a few years if the label on the back disappears, I'd have a hard time remembering how to use it.
My other interest: http://channelf.se
- e5frog
- Vic 20 Nerd
- Posts: 551
- Joined: Sat Feb 17, 2007 5:46 pm
- Website: http://channelf.se
- Location: Sweden
- Occupation: Service Engineer
Re: How to hack cartridges
Found my original post about it:
sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=11&t=2572&p=27949
EDIT:
I thought I should do something about the power up reset for the latch (74LS174), I had added a 74HC14 just for that and also a cap and a bunch of resistors to try and find a working combination and it still worked so-so sometimes and started up and BASIC.
Then I suddenly realized, why not use the plain /RESET, pin "X" on the cartridge connector to reset also the latch?
I tried it, seems to work every time at every startup. The RESET is low for a second or so and then goes high - just what is needed to hook it directly to the /CLR of the latch.
So now I could remove all that extra circuitry and only have the SMD latch there glued up-side-down, a pair of diodes, resistor and some wires as well as a 10nF (I think) cap between IO3 and +5V (don't recall why right now but I'm sure there was a reason).
Nice to finally have a homemade multi-cart with all favorites (and then some) that works properly.
Updated schematic:
sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=11&t=2572&p=27949
EDIT:
I thought I should do something about the power up reset for the latch (74LS174), I had added a 74HC14 just for that and also a cap and a bunch of resistors to try and find a working combination and it still worked so-so sometimes and started up and BASIC.
Then I suddenly realized, why not use the plain /RESET, pin "X" on the cartridge connector to reset also the latch?
I tried it, seems to work every time at every startup. The RESET is low for a second or so and then goes high - just what is needed to hook it directly to the /CLR of the latch.
So now I could remove all that extra circuitry and only have the SMD latch there glued up-side-down, a pair of diodes, resistor and some wires as well as a 10nF (I think) cap between IO3 and +5V (don't recall why right now but I'm sure there was a reason).
Nice to finally have a homemade multi-cart with all favorites (and then some) that works properly.
Updated schematic:
My other interest: http://channelf.se