Re: [stella] My First Atari 2600 Game

Subject: Re: [stella] My First Atari 2600 Game
From: Thomas Jentzsch <tjentzsch@xxxxxx>
Date: Tue, 08 Oct 2002 09:20:51 +0200
Christopher wrote:
>How are you getting the columns so far left? Usually doing the 
RESP0/RESP1 at the first visible cycle results in the sprites 
being displayed about 1/5 of the screen in (ie: The leftmost 
position on mine).. Are you using the wrap around from drawing 
13 (I believe it was 13..) copies? I tried that but found the 
gap after the last wrap around and the first "real" sprite to 
be too wide.  Hmm, gonna have to boot my girlfriend off the TV 
and take a look at it on the real thing...

IIRC it's a combination of late RESP and changing NUSIZ. I also 
tried to use HMOVE to blank what's left over, but not in that 

>Yeh, I hear ya - For ages I did my Vectrex dev work with 
emulator and burning EPROMs (Like with the 2600 the emu is 
good, mostly, but not quite there for everything (ie: Neither 
Vectrex emulator draws curves quite properly...) and you 
periodically need a reality check on the real thing). 

Fortunately z26 is better, I didn't even have to burn a ROM. 
And for the very last tests, Eckhard Stolberg was very helpful 
(as always!).

The main problems of all 2600 emulators are with weird HMOVE 
and RESPx tricks and with early overwriting the contents of the 
HMxy registers while HMOVE is still active.

Normally that's no problem at all, because they emulate all 
*existing* games very perfect (they are tested on real hardware 
:-), but during new developments, you make mistakes that 
sometimes aren't emulated correct.

And there is a problem, when you are developing for an yet 
unsupported controller. But then again, there is always 
Eckhard... ;-)

Have fun!	

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