VRCVI: The ultimate Family Computer multicart !

VRCVI Multicart !




(sorry about the sub quality pictures I only have an cellphone camera available right now... :shrug

Screen grabs made with dscaler and real hardware:

Moryou Senki Madara:


Esper Dream 2:


Akumajou Densetsu:


SRAM was expanded to 32KB and divided by four compartiments. This layout supports up to 4 512KB games. Since only three games are known to run on this hardware, I believe it's a complete multicart... :lol: And each compartiment/partition of the save ram is isolated for it's respective game.

The ROM versions used on the compilation were translated to English.

Akumajou Densetsu was hacked on it's program to operate properly on the Madara/Esper2 hardware (it has a pair of address lines swapped out on it's original board ...) :thumbsup:

 

that's very nice. what' that on the back of the board, under the PRG?

 

address decoder

 

It's an 74LS32 I'm using to generate an secondary chip select (original /CE for the SRAM from the VRC6 along with /OE and /WE) for the Mitsubishi M5M5256 I'm using as backup memory.

That was needed because the original chip (6264) had two chip select pins and one is used to put it on the safe mode by the small mitsumi SRAM watchdog chip when power is off while the other is used for normal access by the CPU.

The 62256 has only one chip select, making it impossible to use such chip with the watchdog without adding extra chips. :shrug:

I'm thinking of adding an binary counter to swap the games with the reset button to get rid of the ugly wires hanging to the side of the board...

Edit: There's no reset signal on the cartridge slot... O_O
So I can't do anything besides put an 3 position pole switch on the cart... -_-;

 

i know famicom does'nt have a reset pin but some famiclone games use the reset button to switch between games. i remember i had 2 such carts. one with crisis force / batman and the othe one with punisher and a game i don't remember. at least they worked on a famiclone console terminator aka ending man.

 

Phi2 goes Hi-Z on reset so you can build an RC timer for it.

 

Following your idea, I opened an pirate multicart and found this circuitry:

1N4148 signal diode
PHI2 --------|>|----+-----------------|inverter>--------> To multicart latch register.
GND-----------||----|
1nf ceramic cap



So I plan to use that to clock the counter for game switching ! :thumbsup:

As per the last game, I'm going to try an VRC4 game which I just tested on a emulator (I played with the rom header to make it load like if it was a VRC6v game) and since it worked fine on the emulator, it might work on the real thing too. :lol:

Edit: Scratch the VRC4 thing lol it DOES NOT work.

Edit2: I added an 74LS393 with the above circuit. It worked a charm but to my dismay, the bad page (page 4) with the VRC4 game shows up.

I regretfully added an extra chip (74LS08) to reset the counter once it reaches 3, making the memory bank swap before the CPU can fetch the first instruction from ROM.

So the three games now circle around starting with Akumajou Densetsu.

I'm VERY glad it was not needed to drill the cartridge casing. I didn't cut a single track on it's board.

Not damaging anything inside or outside the cart made me very satisfied.