Re: [stella] a $16 question...

Subject: Re: [stella] a $16 question...
From: Chris Wilkson - MCD <cwilkson@xxxxxxxxxxxxx>
Date: Fri, 30 Jan 1998 09:20:43 -0800 (PST)
> > The info I have doesn't say anything about initialization.  Is this handled
> > by software?  Ie. are the last few bytes of each 4K page identical...same
> > RESET/SWI vectors, etc?  (This is what I think)  Or does the cartridge always
> > powerup to the same 4K page?
> 
> Random startup is not a big problem.  Besides the reset/swi vectors you
> need to duplicate a bank-switch to get the game started:
> 
> 	org $x000	
> 	sta $FFF9	;switch to main startup bank, in this case $F000
> 
> bankXcode:		;in $F000, this is the actual game startup routine
> 	...
> 
> 	org $xFFC	;reset/swi vectors in case we start in this bank
> 	dc.w #$x000 
> 	dc.w #$x000
> 
> I think that's how it was actually done in Atari carts, but even if not
> it should always work anyway through the magic of software ;)

This is what I thought.  Although it's just as easy to designate a startup pa
page and force it during the powerup sequence.  With no extra parts required.
But doing this only saves 12 bytes.  Not a huge gain with 16K on hand. :)

-Chris


--
Stella list is Administered by krishna@xxxxxxxxxxxx <Glenn Saunders>
Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/stella.html
+-shameless plugs-------------------------------------------------------+
| Stella documentary at http://www.primenet.com/~krishna                |
| Nick's VCS links via http://www.primenet.com/~nickb/atariprg.htm      |
| Write the best game, win framed autographs of famous Atari alumni!!   |
+-----------------------------------------------------------------------+

Current Thread