16K games and startup vectors

[+johnnywc]

Hello all,

 

I have made a 16K game and I'm having a small issue when running it on real hardware (using a CC2).  If I don't specify F6BANK0, it will not start up properly.

 

In banks 1, 2 and 3, I have setup my vectors like so:

 

ORG	$4FF4
RORG	$FFF4

SwitchToBank0
bit  	$1FF6; $FFF4

.byte  #$FF, #$FF, #$FF; holder for the JMP in bank0

.word   SwitchToBank0; $FFFA
.word   SwitchToBank0; 
.word   SwitchToBank0

 

In bank 0, I have the following:

 

jmp     Start; $9FF7  

.word	Start  
.word  Start; set start vector
.word  Start; set interrupt vector

 

Start points to $9000.

 

Any ideas? Is there a way to force the emulators to start in a certain bank? Through z26 it appears that the program always starts up in bank0 but through the CC2 it would appear that it's starting up in another bank. Again - if I use the F6BANK0 option, the game runs fine.

 

Any help is greatly appeciated.

 

Thanks,

Edited January 26, 2006 by johnnywc

[Cybergoth]

Wouldn't the third byte of the BIT instruction and the complete JMP instruction sit on bankswitch hotspots? It should work if you leave $FFF6-$FFF9 completely empty in all banks. The JMP possibly strobes three hotspots at once and it may be vague what side effect will determine the "winning bank" in case...

 

BTW: Instead of the JMP you can just BRK, as you have that vector pointing to Start as well

[+johnnywc]

Wouldn't the third byte of the BIT instruction and the complete JMP instruction sit on bankswitch hotspots? It should work if you leave $FFF6-$FFF9 completely empty in all banks. The JMP possibly strobes three hotspots at once and it may be vague what side effect will determine the "winning bank" in case...

 

BTW: Instead of the JMP you can just BRK, as you have that vector pointing to Start as well

1007224[/snapback]

 

Thanks for the tips - I moved the code out of xFF6-xFF9 in all banks and it works perfectly. Even replaced the JMP with a BRK for good measure...