Atari VCS Development – Day 3 – Customising my Kernel

I decided to have a play around with my Kernel code in an attempt to see if I could get some variants of graphics on the screen, whilst I’m ignoring my sprites I wanted to attempt to get a power bar working using the background alone, as I can use the NOP command to delay for 2 cycles, I can decided how long each power bar is with those commands.

I’m still experimenting with the Kernel code to wring some more out from it. But I now have more colours on one line which could be used for some sort of effects in the background. It’s not that exciting to view though so, no point in putting an image on here. At least, not until I’ve played around more with the code.

I’d like to get two different sprites on one line without any negative effects, I may have to use some flickering in order to achieve this though, racing the beam is a tad tough!

Atari VCS 2600 Assembly – Day 2

Gone is the coloured background. Here instead, are some sprites and missiles!

spritesandmissilesI’ve hoodwinked the 3rd bunch of sprites in-between scanlines and, whilst it’s proving tough to get the missiles aligned horizontally, they are firing on joypad input and both players have seperate inputs available.

I might try to demake Invasion VS onto this from my Original OUYA release. It was pretty fun to play against another person. Not sure how I could hoodwink AI into 4k but I’ll see!

I’m thinking mode switches to change the display type for each player, different player counts could lead to some decent gameplay, think air sea bttle but with players facing each other, that’s what I’m aiming for here.

It’ll be tough but I’m pleased with making some progress on the kernel today. I’d love to speed it up a bit mind you!

Atari Game Development and Assembly – Day 1

Well, here goes nothing. Or, in fact, something!

With the right tutorials I’ve got my head around some Assembly, after a while of research and learning how to structure loops and the equivalent of while loops I feel like I’m getting somewhere!

I’m limited to a paltry 4k of ROM space and everything is being drawn on a line-by-line basis, I doubt I’ll need all 128 bytes of RAM to be honest as there’s not much room to play around!

Still, so far I have a background and moving missile sprite, which moves based on Player Input. There’s even some tones being generated on movement which is kinda cool.

Coloured Bg and Yellow Missile, Yay!
Coloured Bg and Yellow Missile, Yay!

Plus there’s a register dedicated to handling collision detection, how cool is that? I mean, you just check the set bits and you know what has collided with what!

Right, I’m going to see how I can get a sprite or two on there, seeing that it can only handle 2 sprites, 2 missiles and a “ball” on the hardware I’ll be hard pressed to make something playable!

Really Useful Links for anyone interested:

6502 OpCodes –

AtariAge Tutorials –