Denial

It is best to use VR/W line from edgecard connector (pin 17) rather than pin 18.

Wire this to the /WE pin (#27) on the STK12C68 and you should be good to go!

It's OK...I've worked it out.

It connects to Pin 27 Write Enable.

It now works like a charm.

Thanks for your help.

hawk wrote: It now works like a charm.

Excellent!

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.

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.

That label looks great.

Previously I have internally called this design a BrianCart, but Flexicart works just as well.

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.

hawk wrote:The cart isn't really PAL only, except I couldn't think of anything else to put there.

How about VIC-0000 since it can be lots of things or nothing at all.

gklinger wrote:

hawk wrote:The cart isn't really PAL only, except I couldn't think of anything else to put there.

How about VIC-0000 since it can be lots of things or nothing at all.

I like that...or alternatively VIC-???? or VIC-****

Bugger...now I've got to print another label

The new Flexi-Cart Label has been uploaded.

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.

e5frog wrote:An inspirational image - you don't see the bird's nest when it's inside the cart.

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.

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.

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: