-----Original Message-----
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
To: stella@xxxxxxxxxxx <stella@xxxxxxxxxxx>
Date: Saturday, January 17, 1998 10:23 AM
Subject: Re: [stella] Screen shots
>Is this with pixel doubling, so that the low two bytes of the 32 bits are
>equal, and the high two bytes are equal? (if the 32 bits are in EAX, then
>AH=AL, and the top two bytes of EAX are also equal.) In that case, you've
>got two 2600 pixels per 32-bit store. For tweaked mode, you'd just need to
>write AL to the screen, SHR EAX,16, write AL to memory, increment counter.
Yeah, pixel doubling happens at color change time, and I was thinking PC
pixels in my counting not 2600 pixels :) But this way of doing it only
happens when doing background and playfield only and we know there's no
objects in the way. If there are players or other objects to do, things
happen more or less the way you might expect. So for background and
playfield you wouldn't even need the SHR, but in the other cases, you'd
probably write a byte instead of a word? You tell me!
>>If you start out doing 320 by 200 tweaked, once the addressing and
rendering
>>issues are resolved, it's a small step to 320 by 240 or 360 by 240. I
want
>>one or the other of these modes because then you can display a tall game.
>
>True. And you can get to 480 lines, so you can get the venetian-blind
>effect for tall games too. Why would you want 360 across for a 2600
>emulator, though? 320x480 is perfectly doable, even if it has the worst
>aspect ratio since 640x200 mono CGA :)
I was thinking 360 because most people are used to looking at games at 320
by 200. If you go to 320 by 240 they might look squished. At 360 by 240
you could squish them in both directions to get close to the aspect ratio
people are used to seeing.
>> Many visual artifacts disappear when the game is synchronized with
>>the monitor.
>
>Do they? That'd be nice too.
Yeah, z26 runs at VGA speed now, wrong play speed, but check out Yars'
Revenge then look at it on PCAE running at 60 fps. Our synchronization is
still not perfect under Win95, I think maybe we need to use vertical non
display interval instead of the retrace pulse, or maybe even page flipping
:) but you get the idea.
>Got the source. Er, what compiler and assembler exactly are you using...
>also, where's the part that puts it into VGA mode, so I can change that to
>mode-X? I could find it myself, but it's easier to ask you :)
That would be in graphics.asm.
I'm using Turbo Assembler 1.02 and Turbo C version 2.0. Assembly code
SHOULD be MASM compatible though. I've tried it before and it worked but
not lately :) If finding something compatible enough to develop with turns
out to be a problem, let me know. I may have a copy of MASM I'm not using,
and I may have a copy of Microsoft C I'm not using :)
>I haven't done x86 assembly for a while.. looking at this, it feels like a
>high-level language compared to 6502 assembly, though :) Damn, the 2600
>would be easier if we could do stuff like CALL [TIAREGVECTOR + EBX*2] :)
I had a hard time with it when I was first learning it. I was used to
something much simpler too (D.G. Nova) :)
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