NES PCB: What does this switch do?

MatthewCallis · Post by **MatthewCallis** » Sun Jul 06, 2008 9:44 am

I've got this cart, it's a boring game but I can't figure out what the switch does. I've tried it both ways but no visible difference, switching it while on only makes the screen flicker. Any help on the subject would be great!
Thanks!

kyuusaku · Post by **kyuusaku** » Sun Jul 06, 2008 9:50 am

Do you know about nametable mirroring? Also do the wires go to the switch?

MatthewCallis · Post by **MatthewCallis** » Sun Jul 06, 2008 9:53 am

Very little; as in I understand the concept but have a little difficulty getting it to work perfectly in my emulator.

Bregalad · Post by **Bregalad** » Sun Jul 06, 2008 9:54 am

This switch very likely change nametable mirroring. Check if it's connected to the CIRAM A10 line.

MatthewCallis · Post by **MatthewCallis** » Sun Jul 06, 2008 10:05 am

What would be the point of this switch if it toggles the name table mirroring? I guess I don't understand why they would need to change the name table mirroring externally.
The game is Portopia Renzoku Satsujin Jiken / ポートピア連続殺人事件 I just refound the name of it.

Post by **tepples** » Sun Jul 06, 2008 11:00 am

MatthewCallis wrote:What would be the point of this switch if it toggles the name table mirroring? I guess I don't understand why they would need to change the name table mirroring externally.

Perhaps to use different games on the same developer board. Imagine a studio working on two titles that use different mirroring, where one title's team gets to test on RealHardware(tm) in the morning and the other in the afternoon.

MottZilla · Post by **MottZilla** » Sun Jul 06, 2008 12:51 pm

That's my guess too when I first saw it. It would be very useful on a board with sockets to have a switch to select H/V mirroring. Alot easier than having two seperate boards for horizontal and vertical scrolling games. The guess is reinforced by the lack of any memory mapper on the board.

If the game scrolls, having the switch in the opposite position should make the scrolling messed up.

Bregalad · Post by **Bregalad** » Sun Jul 06, 2008 1:00 pm

Well I don't remember this game to scroll. Acroding to bootgod, it uses vertical mirroring, while the other NROM game developped by the same company used horizontal mirroring (Door Door), but the game came out significantly earler. The other game being under developpement at the same time uses vertical mirroring as well and is CNROM (Dragon Quest), I don't know if it could have been tested on that board.

tokumaru · Post by **tokumaru** » Mon Jul 07, 2008 2:25 am

Well, the fact that the game does not scroll has nothing to do with the board having a mirroring switch... in fact, if the game doesn't scroll, that must be exactly why the poster hasn't noticed anything. Anyway, if a company has a devcart with a mirroring switch, they'll test their games with it whether they scroll or not.