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The Southsider

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About this blog

Atari musings and random thoughts

Entries in this blog

 

Chetiry

As many of you will now know, I have been working on a new Atari 2600 homebrew title called Chetiry. This blog entry should hopefully clear us some of the confusion surrounding the project!   Chetiry is a tetromino matching game that should be familiar to most gamers. The original Chetiry project (Chetiry means 4 in Russian) was started by Zach way back in 2006. However, Zach retired from Atari 2600 homebrewing in 2009 with the Chetiry project still unfinished. I had been hoping to see

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Star Castle RC1

Star Castle is basically feature complete now, so here is the first release candidate for testing.     Please note that you must upgrade to the latest Stella 3.6.1   The main changes this time are: New sound effects by LS_Dracon Title screen music by Kulor High score table (will only work on Harmony cart) Improved collision detection Different ring colours on each wave During the game, the following can be changed: Pressing SELECT will skip to the next wave (this i

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Star Castle Playable

Here is another Star Castle update. The game is now playable, although more tuning is required and there are some rough edges.     There are too many changes to list, but some of the highlights: 32 waves of increasing difficulty More awesome graphics by Nathan - especially the title screen and ring explosion! Mines can now detach and reattach to the rings as in the arcade NTSC, PAL60 and B&W colours (press SELECT on the title screen) As before, you need Stella 3.5.5 or

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Perfect Harmony

A couple of entries back I was pondering which project to do next after Juno First. Since then, I have been working on the semi-secret Harmony/Melody cart project. This project is now close to completion, and so I think it is safe to write some details about it here. To keep things simple, I'll only talk about the Harmony cart. The Melody cart is the same, but without the SD card and USB options.   The Harmony cart project was started by batari around a year ago. As I understand it,

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AtariVox

When I first heard about the AtariVox I wasn't too impressed with the sound quality, and decided not to bother getting one. However, I changed my mind after seeing a demo of Man Goes Down at the vgXpo a few years ago. I realised that the sound quality was a perfect match for the Atari, being broadly equivalent to the quality of speech chips back in the day. I now think it would sound "wrong" if the Atari were to produce high-quality speech, just as it would sound unnatural if Stephen Hawki

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Star Castle Brainstorming

Here is another minor update to Star Castle: The rings can now move at variable speeds - I have slowed them down a bit in this version. The ring segment now disappear immediately when they are hit. The rings will regenerate when the outer ring is removed. The gun will fire projectiles at you when the inner ring is breached.   The big question now is how closely the 2600 version should match the arcade version. There are two sticking points, where I think it might be better to

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Star Castle Developments

There has been a lot of buzz recently about Scotts Star Castle kickstarter (just a few days remaining to grab a copy). It has prompted some people to speculate about this effort, so I thought I would post an update of where things are.   This project is still very much alive, and the plan is to eventually release it through the AtariAge store. The main development is that Thomas Jentzsch (Thrust+, Boulderdash) is now involved, and the coding will now be a joint effort between him and myself.

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Star Castle Update

Here is a quick update on my Atari 2600 Star Castle port: Awesome new sprites supplied by Nathan Basic sound effects - will improve in future versions Stars in the background 2 bullets on-screen Ring segments turn to dots after 1 hit (disable using Left difficulty switch) Bullets wrap around the screen edges This version uses a new bankswitching type, so you will need to upgrade to Stella 3.5.5 to make it work. It doesn't work on the Harmony cart yet - but it will soon.

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Star Castle Ship Movement

I have made a little more progress on my Star Castle demo. You can now move the ship around the screen and fire bullets, although there is no collision detection yet. The controls are: Joystick Left/Right - Rotate Joystick Up - Thrust Fire - Fire Bullets I have been trying to match the ship movement with the arcade version (by comparing with the MAME version). I think it is now reasonably close, but let me know if you think it needs improvement?     The ship sprite is te

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Taking a break

I'm going to be taking a break from Atari 2600 homebrewing for a while due to real-life considerations. I will still be lurking around the forums, but I won't have any time for coding for some time. Fortunately the various projects that I have been involved in are in good hands: Chetiry will be released at the PRGE later this month and will be available in the AA store shortly after. Star Castle is being partially rewritten by Thomas Jentzsch - he has made excellent progress and shoul

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Star Castle Colour Kernel

I figured out how to make my Star Castle kernel display in colour. I think this looks much better than the monochrome version posted in my previous blog entry.     The technique was inspired by supercats kernel, but as before I am only using a single sprite to draw the rings. This leaves the other sprite and missile/ball free.   The kernel uses a number of advanced tricks, such as updating the colour registers while the sprite is being drawn. Hopefully it will work on a real 2600 as

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Star Castle Collision Detection

After much head-scratching and code optimisation, I finally have collision detection working! In this version you can shoot the ring segments. For now they only take one hit, but this can easily be changed.     I think I now have all of the pieces necessary to make the game. However, I now need to put it all together and rewrite significant parts of it, such as the kernel. The main issue now is running out of ROM space as all the unrolled code has nearly used up the full 12KB.   Let

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Flicker Fest

This is just a quick update on my Juno First game. I hope people don't mind me using this blog as a beta testing area. However, I find it useful to post these development versions as the folks here are quick to spot bugs and problems that I might not notice otherwise. The previous versions had a number of serious bugs, but I hope that most of these have now been resolved. The main features this time are: All 20 possible sprites are now displayed on screen. This causes some serious fl

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Star Castle Improvements

I have made a little more progress on my 2600 Star Castle demo: Ship rotation is slower. Ring colours now match the arcade version. Player bounces off the rings. Centre gun tracks the player position. The main issue now is collision detection between the bullets and the rings. I haven't yet worked out an efficient way to detect when a ring sector is hit by a bullet, and the code is starting to get tight for cycles.     Let me know what you think?   Chris   starkernel4

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Star Castle Kernel

The recent threads on Star Castle for the Atari 2600 have been rather annoying, so I decided to see how difficult it would be to write my own version.   It turns out not to be too difficult - I was able to write a basic kernel with rotating shields in a single weekend. I just went for a simple implementation using extra RAM (FA bank-switching) instead of pre-calculating all the ring data. The advantage of this approach is that the rings can be made to spin at different speeds.     It

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Juno Title

This is just a quick update on my Juno First project. I have now created the title screen, thanks to some more amazing artwork by Nathan. I was aiming to reproduce the look of the Arcade title screen as far as possible, and I think I have managed to do a reasonable job given the limitations of the 2600 (arcade shot on the right ):     The logo is 96-pixels wide and is created using the Homestar/Ruby Runner flickering trick. It is necessary to use the Phosphor option in the emulators

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Juno First Betas

I had a holiday yesterday and was able to spend some time finishing Juno First. I have now posted a beta version in the homebrew forum for general testing.     There are quite a few changes since the last version that I posted, namely: There are now 32 unique waves, and I have made many changes to the previous set of 16. The game actually has 64 waves in total, but the second 32 are the same as the first with a higher speed setting. The fuel gauge now empties at twice the spee

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Next Project

With Juno First nearly done, I have started to think about my next Atari 2600 game project. I don't have anything decided yet, but these are the various projects that I have been considering: Prince of Persia - I wrote a reasonable kernel for this a few years ago. However, the main issue is that it requires extra RAM and there aren't any such carts available yet. The other issue is the massive sprite requirements of the game. Le Geek made a good start on the sprites a while back, but

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Score Kernel Revisited!

It seems that nobody was impressed with my 16 character kernel last time - the main problem being the introduction of unnecessary flicker! I wasn't entirely happy with it myself, but I couldn't think of a better solution at the time. However, based on batari and Manuel's comments I decided to have another look at the no-flicker 13 char text demos. The 13+2 char demo uses a neat trick of rewriting NUSIZ during a scanline to squeeze in an extra two characters (in addition to using the ball a

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Pssst! Kernel

It's been a while since I posted anything here, so here is a quick entry about a recent Atari 2600 project of mine.   I had an idea for a holiday-cart based around the Ultimate game Pssst! for the ZX Spectrum. For those unfamiliar with the game, here is a flash version of Pssst!, and a YouTube video of Pssst!.   The aim of Pssst! is to protect the flower growing in the centre of the screen from a variety of different bugs. The bugs are destroyed by spraying them using the aerosols positi

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Harmony Memory

The pre-release version of the Harmony cart is now finished and is being sold at the Portland RetroGaming Expo. I expect that the bug reports and feature requests will start arriving soon! Before they do, I though I would write a little more about how the Harmony driver software works.   The Harmony driver is written using a mix of C and ARM assembly language. The ARM assembly is used for the performance critical stuff, like feeding the Atari with instructions, while the C code is used f

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Star Castle Mines

Here is another small update to my Star Castle demo on the 2600: The mines now follow you around the screen. They will reset to the centre if they go off screen. You can shoot the mines, and collisions between the ship and mines are detected (the screen will flash). Ship rotation is now much slower. There are still a few issues with the ship and mines at the edges of the screen, but I'll fix these later. The mines are flickered at 20Hz so that 3 can be displayed. The flicker w

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Flashing Cockpits

There is a discussion currently in the homebrew forum about adding a flashing cockpit to the Juno First ship. One approach would be to use the ball sprite overlaying the player sprite. The ball sprite is used for the laser and is already correctly positioned (horizontally), but I can't find the spare cycles to enable and disable it at the correct time. The main loop where the ship is drawn is a 1LK as follows (the actual code is in kernel1.h in the zip attached to the previous entry):  

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13 Lines

I decided to experiment again with my textkernel to see if copying the text into zero page memory would be useful. The advantage of using zero page RAM to hold the text is that it removes the need for the text to be in the same bank as the display kernel. The text can be loaded into RAM in one bank and then displayed by bank-switching into the display kernel. Another practical advantage is that it becomes possible to create text dynamically in RAM without the need for the text to be fixed

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16 Char Text

I have written another text kernel which displays 16 characters. This may seem pointless, given my earlier 24-char and 28-char kernels, but it has several nice features: Uses less ZP memory (46 bytes total). Shows more lines on screen (14). Text width is a power of 2 (for easy calculations). Kernel has loads of free cycles (around 40 per scanline), e.g. could have a PF image underneath.   The main reason for writing this kernel is to allow the Juno First score table to be

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