Galaxian - improved free play

[philmurr]

Jumping on the "improved free play" bandwagon...

Galaxian is pretty good in that it has free play built in, so you don't need to keep crediting up the game to play it. Bad thing is that when it's in free play mode, it stays on a static screen waiting for 1 or 2 player button to be pressed.

I've spent a bit of time going through the Galaxian code and have made a little hack that will let the game do its attract screen, but doesn't need coining up to play, just press 1 or 2 player start and the game will begin.

It reads the "unused" DIP switch, if the switch is on, the hack is enabled, if it's off, the hack is disabled and the game runs as normal.

No need for a screenshot as there's nothing to see!

All you need to do is modify 2 ROMs as below (use HxD or similar):-

ROM - galmidw.u

Address 03D7 - change code to C3 00 26

ROM - galmidw.z or 7L (depends on whether you're using Midway or Namco code)

Address 2600 - change code to 3A 12 40 CB 5F 3A 02 40 CA DA 03 3A 11 40 CB 47 3E 01 20 0F 3A 11 40 CB 4F 3E 02 20 06 3A 02 40 C3 DA 03 32 02 40 C3 DA 03 E1 93

 

[Hurray Banana]

Nice one phil

 

[Battlezone]

That's a great little change, I wish more games showed the attract mode
when set to free play.

 

[edwoodjnr]

Good work Phil, getting rid of coin up buttons and screen burn is the way forward

 

[cmonkey]

Nice work. Looks like I've started of wave of improved free play mods!

 

[virtvic]

Nice! Can you do every other pcb too, please?

Ta. X

 

[Judder]

This is an excellent modification from Phil (as normal) and for anyone actually modifying the ROM files themselves, the modification to ROM 7L is from byte 600 onwards as per below (hex 2600 - (4 * hex 800) = hex 600. On a Mac I used Hex Fiend (make sure select Edit -> Mode -> Overwrite mode)