Re: More thoughts about Lode Runner & other multiload games...

[Steve Nickolas <usotsuki@buric.co>]

On Fri, 28 Sep 2012, Hot Rod wrote:

> OK, so in taking a quick peek at LoGo's version of LR, it looks like the 
> high score table is on track $0C, sector $0F. And that this is stored in 
> memory at $1F00, and is either read or written via the routine at $6359. 
> You can see where it's called with the A-reg set to either a #$01 (for 
> reads) or #$02 (for writes) and then stores that operation code first, 
> followed by setting up the track, sector, and buffer address (i.e. track 
> $0C, sector $0F, buffer $1F00) as part of the IOB, before calling RWTS 
> with the address of the IOB ($B7E8) loaded in A and Y regs.  This 
> routine at $6359 is called from a few different places though, and I 
> didn't explore them all.  It might be worth first confirming that this 
> is the high score table you're after (track $0C, sector $0F).

Good to have a guru around. XD

Where I enter the code is at 6008, because I skipped some code that did 
stuff (and apparently broke if I called it directly without the disk). 
That code was:

seg000:6000                 JSR     sub_0_87A2
seg000:6003                 LDA     #1
seg000:6005                 JSR     sub_0_6359

Which calls, well, the exact function you pointed out.  XD

I never seemed to make note of this function, though it does seem to be a 
vector into RWTS.

I don't see any code (but it just might be I haven't analyzed it yet) to 
actually *set* those values, so perhaps that code *only* handles the high 
score table?  I'll test that.

*a few seconds later*

No, this is actually the main read-write code!  All the 3 functions I was 
looking for vector through 6359.

-uso.