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Memoirs of an X register

Horizontal Scrolling works, WHEEE!

Posted by tschak909, 10 July 2006 · 128 views

Well guys, after a lot of debugging, I have the horizontal scrolling motion working properly.. I have sped it up so that it could be seen.

I have attached the code below, but basically my approach is this:

* use the main line code to set global states, go left? go right?
* use the VBI to update actions that need to happen per frame, update the zero page...

Screen Tests II!

Posted by tschak909, 01 July 2006 · 177 views

Greetings all,

Am nearing the final revision of the playfield layout that I want. I thought I would paste a screenshot so that everyone here could see what I am working on. I have posted two shots, one with NTSC emulation, and one without, it's giving me a reference as to what I need to correct, graphics-wise.

(yes, I am aware of the hanging pixel on...

Vertical Scrolling Techniques

Posted by tschak909, 28 June 2006 · 131 views

I've done the first little test of some vertical scrolling techniques using a moving ANTIC JMP instruction, so far it works, i just need to alter the counter on the up cycle slightly, but one question.. how do I make the scrolling completely smooth, with no jumps?


Source Code:


Learning POKEY

Posted by tschak909, 27 June 2006 · 139 views

I took some time out, today, to learn the basics of bit-banging the POKEY chip.. I will be doing more complicated experiments as my development with the invaders game continues....




Retooling and drawing.

Posted by tschak909, 21 June 2006 · 202 views

Wanted to let you guys know, that I am still working on the game. I've been in the process of re-building it in ATASM on the Linux side, instead of using MAC/65 inside the Atari 800 itself. I got tired of being squinched into 40 columns.

My current goal right now, is to refactor and get the invaders display working again, then work on getting the...

Invaders: Working on Player Graphic

Posted by tschak909, 15 June 2006 · 135 views

Working currently on the player graphic. I wanted the player to be able to have a temporary shield, so I designed two definite states, with and without shields, which will be rotated with the character set providing the animation. I am also reorganising the display list to something more proper for horizontal scrolling.


Screen Tests!

Posted by tschak909, 09 June 2006 · 221 views

I am slowly progressing. I have the first DLI routine set in place to set the colors. Had to use a chain of routines each modifying the DLI vector at the end of each pass. Because I had to make four distinct color changes, I decided to hard-code them into the routine, so that I could minimise the number of cycles being done. I will be modifying the look of...

Invaders Graphics Done

Posted by tschak909, 08 June 2006 · 265 views

Decided for my first game to be a Space Invaders type game. Did some initial sketching in Envision, and am now posting the results of my work.

The graphics are meant for antic mode 4 displays, with each line setting a DLI to change the color palette of each line essentially doing a hue change.. I chose to use all four colors for a shaded look rather than a...

Reading the Atari 800 HW Manual

Posted by tschak909, 07 June 2006 · 148 views

Ahhh, some nice DRY evening reading.. The Atari 400/800 hardware manual. Continuing my quest for getting a grasp on the whole system... I found this paragraph in section 2 slightly amusing....

Theoretically, it is possible to write a program which changes graphics or colors "on the fly", i.e. during the middle of a TV line. However, with...

Learning DLI

Posted by tschak909, 04 June 2006 · 124 views

After fixing the little display list weirdness, it works now. A tight locked interrupt loop that changes the color of every four lines (more or less) via a display list interrupt, using an increment inside the interrupt routine to change a page zero counter. It runs very fast, so it tends to strobe.. Now i need to learn proper delaying techniques. I will be...

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