more games on 1 cart

downloader · Post by **downloader** » Thu Oct 12, 2006 11:20 am

i'll go for the 3 pins option.
middle pin connected to gnd.
left pin to 5v on 1 rom.
right pin to 5 volt on rom 2.

Zack S · Post by **Zack S** » Thu Oct 12, 2006 11:56 am

downloader wrote:i'll go for the 3 pins option.
middle pin connected to gnd.
left pin to 5v on 1 rom.
right pin to 5 volt on rom 2.

Did you mean middle pin connected to +5V source? I hope you're not planning on using the switch to pull the ROM supply voltage to GND.

Also something to consider is making sure the switch you use is a break before make type. You don't want to power up both ROM's at the same time when switching between the two.

downloader · Post by **downloader** » Mon Oct 16, 2006 8:17 am

Well....what pin would you connect where?

Quietust · Post by **Quietust** » Mon Oct 16, 2006 9:05 am

downloader wrote:Well....what pin would you connect where?

You should be pulling whichever ROM's address lines or chip/output* enable to specific states.

If you're going to put all of the games on a single ROM chip (which is recommended, since otherwise your cartridge board will be huge), you'll want switches to pull the ROM's upper address lines (A15+ if each game is 32K, A18+ if each game is 256K, etc.) to either +5V or GND; if you use one ROM for each game, then you'll want a switch to pull one ROM's enable to GND and pull all of the others to +5V (since enables tend to be active low).

* Generally, NES carts tie one enable to GND always and connect the other one to /(A15 & M2) - whichever one isn't connected to the cart edge/mapper can be hooked up to your switches.

Post by **Memblers** » Mon Oct 16, 2006 11:25 am

Or if you mean what pin of the switch, check it's datasheet (or better yet, verify it with a multimeter).

Personally if I was gonna do it I'd use a DIP-switch and mount it with resistors on a little universal PCB (like the little ones they've got at Radio Shack - almost the only part for a decent price there..). I guess it depends on how many games you'll have on it though. Having a bunch of individual switches hanging by wires would be kinda messy. 32 NROM games on a 1Mbyte EPROM would use 5 switches.

proveaux · Post by **proveaux** » Sun Jun 10, 2012 5:31 pm

Im still confused on this. Im planning on putting 2 smb1 hacks on same eprom. The only difference between the 2 will be the graphics for the same hack, so i plan to use a 27c256 for the prg. I also plan on using same for chr but only because thats what I have already ordered.

So let me see if I got this part right for the chr, which i have two different ones.
copy /b original.chr+originaltoo.chr+edit.chr+edittoo.chr chr.bin

For the switch I plan on using a DPDT latching push button because i already have some. This where I get confused. What goes to what pin on 256 eprom and switch and 128 eprom in cass I get some?

27C64/128/256/512 EPROM pinout
---_---
+5V- |01 28| - +5V
A12 - |02 27| - A14
[PGM] A7 - |03 26| - A13
[NC] A6 - |04 25| - A8
A5 - |05 24| - A9
A4 - |06 23| - A11
A3 - |07 22| - /OE
A2 - |08 21| - A10
A1 - |09 20| - /CE
A0 - |10 19| - D7
D0 - |11 18| - D6
D1 - |12 17| - D5
D2 - |13 16| - D4
GND - |14 15| - D3
-------

tokumaru · Post by **tokumaru** » Sun Jun 10, 2012 6:46 pm

The switch will only change the CHR then? SMB1 is NROM, meaning it has 8KB CHR-ROM, so a 16KB EPROM (27c128) would be enough, but you can use a 32KB one without problems.

13 address lines are necessary to address 8KB, so A0 to A12 should be soldered to the board normally. A14 (if you're using a 32KB chip) should be soldered to GND, because you'll not be using the upper half of the chip. A13 goes to the switch, which will select between connecting it to GND or +5V.

infiniteneslives · Post by **infiniteneslives** » Sun Jun 10, 2012 7:57 pm

Yeah just don't get confused about CHR A13 from the NES cart edge. It still goes to the rom's /CE line. Like tokumaru said the rom's A13 goes to your switch.

proveaux · Post by **proveaux** » Sun Jun 10, 2012 8:09 pm

Ok let me see if i got this. Bend up A13, pin 26, and solder every thing else like normal. Wire A13 to center of switch. Wire left to +5v, pin 1 or 28. And right to GRD, pin 14. Still new to this and dont really comprehend all it yet so forgive me if i totally screwed that up.

Post by **Memblers** » Mon Jun 11, 2012 4:53 pm

The way you're copying the data, if you switch A13 and ground A14, you'll always select the first ROM. You'd better copy the ROMs in alternating order, or put the switch on A14 instead.

tokumaru · Post by **tokumaru** » Mon Jun 11, 2012 5:13 pm

Memblers wrote:The way you're copying the data, if you switch A13 and ground A14, you'll always select the first ROM.

What? I don't see it...

infiniteneslives · Post by **infiniteneslives** » Mon Jun 11, 2012 5:37 pm

tokumaru wrote:
Memblers wrote:The way you're copying the data, if you switch A13 and ground A14, you'll always select the first ROM.
What? I don't see it...

So let me see if I got this part right for the chr, which i have two different ones.
copy /b original.chr+originaltoo.chr+edit.chr+edittoo.chr chr.bin

When A14 is low he's have the original, when it's high he'd have the edit. If he grounds A14 he'll only get the original .chr.

tokumaru · Post by **tokumaru** » Mon Jun 11, 2012 7:29 pm

Ah, I didn't see he was copying the files like that. Yeah, if you ground A14 and switch A13 you have to copy the files like original.chr + edit.chr + whatever + whatever. I suggested it like that because he considered using a 16KB EPROM, in which case it would just go original.chr + edit.chr and A14 wouldn't even exist.

Hamtaro126 · Post by **Hamtaro126** » Mon Jun 11, 2012 7:32 pm

downloader wrote:I think I would use a physical switch.
I think that would be the easy way for me.
I don't know JACK about programming a menu (assembling isn't my strong pint ya know)
Physical switching is possible. I played around with it a little and in theory it should work.

If you want a easy example, Try out No Carrier's 9999-in-1 (3-in-1) example on how to make a menu.

tokumaru · Post by **tokumaru** » Mon Jun 11, 2012 7:40 pm

Hamtaro126 wrote:If you want a easy example, Try out No Carrier's 9999-in-1 (3-in-1) example on how to make a menu.

You could easily hack the game to CNROM and do something stupidly easy like selecting a CHR bank based on whether A is pressed during power on (e.g. when A is pressed switch to the second tileset, otherwise use the first). This would only require a very minor hack to the reset routine.