Date   : Thu, 29 Sep 1994 13:59:40 +0100 (BST)
From   : clr1@...
Subject: Re: CRTC and ULA emulation

> Chris Lam writes:
> Many games use split palette modes, but I can only think of the above two for
> changing screen modes. Maybe Sphere of Destiny does. Speaking of S.O.D, do
> people realise that the speed (it's a "trailblazer" clone) of game is simply
> because the animation of the 3D trail is done purely using colour palette
> switching? Amazing! Exile also uses colour palette hacking (for the water), as
> do many other games I imagine.

I meant to ask about Exile, actually. What mode *does* it run in? it 
looks like mode 1 res, mode 2 colours. Is it fiddling the screen 
boundaries to shrink the screen and make it look less chunky? Or is it my 
eyesight again...

> It depends on precisely what they're changing. The mode in FE20 is simply the
> colour control (ie bits per colour) isn't it? If the resolution changes (eg
> mode 4 vs mode 2) CRTC registers will surely need modifying. I'd be suprised
> if Elite didn't do this somewhere, although I can't remember the modes it uses.

How exactly do these games time it? Is it actually timed by instructions? 
If it is, then all the instructions would need to use exactly the right 
number of clocks! *Shudder*

> Your scheme would have problems with SOD and Exile I expect. Still, it's
> further than I've got :-)

I still can't get my keyboard to work!

+-------------------+-------------------------------------------------+
| /-- |_| /-- | (~  | "And the driving is like the driving of Jehu,   |
| \-- | | |   | _)  | the son of Nimshi, for he drives furiously."    |
+-------------------+-------------------- Second Book of Kings 9 v20 -+
|  Wanted: 486DX2-66 VLB M/board; VLB graphics card; SBpro soundcard  |
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