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Memoirs of an X register



Screen Tests II!

Posted by tschak909, 01 July 2006 · 105 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 · 78 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?

-Thom

Source Code:


;
; TEST PROGRAM TO TRY MY...


Learning POKEY

Posted by tschak909, 27 June 2006 · 90 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....


;
; SOUND01 - PLAY A MUSICAL SCALE
;

.INCLUDE atariequ.asm ; ATARI EQUATES

*=$0600 ; CRAM OURSELVES IN PAGE 6
JMP START ; GO TO START,...


Retooling and drawing.

Posted by tschak909, 21 June 2006 · 96 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 · 87 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.



Next,...


Screen Tests!

Posted by tschak909, 09 June 2006 · 166 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 · 129 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 · 103 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 · 78 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...


dlist weirdness!

Posted by tschak909, 02 June 2006 · 87 views

I am currently trying to build a simple demo program that uses a DLI that increments the color registers. I am thinking if i just increment the zero page registers when the interrupt occurs, I will get a sort of ripple effect. But right now, somehow, the low bit of my LMS instruction is getting obliterated, grr a load instruction going wrong.

have attached...