6809 CPU Emulator project started

CpuEmulator is a CPU emulator project that aims to emulate a CPU (the 6809 to start with), it’s registers, and system memory. It will allow you to monitor registers, flags and memory as you step through code. Having done SharpiEmu for the Sharp PC–1360 Pocket Computer, the concept seems pretty simple. The 6809 has a number of addressing modes, and different opcodes for the same mnemonic. So I’m expecting it to be somewhat more of a challenge.

Initial version will emulate the CPU, memory, and text video mode.

Features

  • Emulate 6809 instructions
  • Emulate 32×16 & 80×24 text modes
  • Emulate the Coco3’s MMU
  • 4K all the way up to 512KB memory options
  • Debugger that steps through code, shows current state of registers, selected memory block, and source code from a listing file.
  • Break points. They are remembered between runs.
  • Memory watcher. When memory at a certain addresses are modified, a breakpoint is triggered so you can see what modified it.

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Bouncy Ball 2 Progress Report #1

Bouncy Ball 2 Progress Report 1. First things first. We need to get the Coco 3 into it’s high resolution graphics mode, then display a little something. To start out small, I decided to create a program that sets the video mode, uses the MMU to map in the video memory, then clears the screen. That part was easy, although understanding the MMU was a little whacky.

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Bouncy Ball 2 Announcement

I’m happy to announce that Bouncy Ball 2 development has started! Design is underway, and the sound system already sounds awesome. We have been able to make the Orchestra 90 sound mad. It’s using full stereo sound, mixing 4 channels, and uses hardly any CPU. We have a lot to learn about the Coco 3. Join us every week or two on the BB2 development blog to watch our progress. We are Lee, Simon, and Paul.

Orchestra 90 CC Stereo Music Synthesizer

Radio Shack Catalog Number 26–3143. The Orchestra–90 CC is a stereo 8-bit audio player for the Color Computer. It works by mapping two addresses in the Coco’s address space to two 8-bit DACs. $FF7A is for left, and $FF7B is for the right. This is the first time I have been able to use this cart, never mind program it! So far, it’s pretty easy to program.

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Bouncy Ball Version 1 Available

Bouncy Ball version 1.0 has been released, and in time for the 2016 25th Cocofest. I was working on a timer bug, and RGB mapping, while Simon was working on the end game sequence. I owe him a case of beer for his efforts, staying up till 2am his time, on a work day! I am so looking forward to watching people play on my Coco 3.

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Optimizing an Imaginary Sprite

There was an interesting thread on Facebook this week that was talking about optimization. They took an imaginary sprite routine and optimized the crap out of it. In this article I’m going walk through the various stages of optimization and provide my own analysis of why the changes were made, and why (or if) the optimization was any good.

I’m going to assume you know how, or are familiar with some arcane programming language, and are either somewhat familiar with assembly or enjoy punishing your brain.

You might be surprised with the results of version 5 and 5p. Sometimes less instructions doesn’t always mean faster.

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Bouncy Ball Public Beta 1

Bouncy Ball Beta 1 is here. See the downloads. This has the lightening fast rendering routine that Simon and myself optimized. Originally a 7 fps C routine to a 50 fps inline assembly routine. I am now running at the Coco’s stock speed of (just under) 1MHz instead of using the 2X speed up on the Coco 3. This also means Bouncy Ball should run on a Coco 2, but I have not tested it yet. The frame rate is buttery smooth but not vsync’ed yet. Some sounds have been added to the game, but in game ball bounce sound is not there yet. And best of all you can now use the keyboard to play!

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Optimization, inside the mind of a mad man

In this article I talk about optimizing the level rendering routine for my game Bouncy Ball for the Color Computer. With the help of the mad man Simon Jonassen, I was able to take the render routine from 7 fps to 50 fps! I was quite surprised at the results. I made a video at the end of this article, and explain things in detail here. I also list a couple resources you might want to have in your back pocket.

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Render conversion to assembly

I started working on converting my level renderer for Bouncy Ball to assembly. Check out the video below. The C is on the left, assembly on the right. The speed difference is about double the frame rate. Although, in the video I forgot that the C version is double buffering, and the assembly isn’t. Assembly also isn’t printing text. So I fixed both versions behind the scenes.

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Bouncy Ball Beta 1 almost ready

Awesome progress over this new years weekend. I started with a 4 page TODO list, and I have all but the end of game sequence done. I still have levels to build, joystick support, and then in-game sound and (maybe) music to implement. Sound will be via Simon’s irq driven routine. I even had some time to start work on Bouncy Ball’s official web page, and some package art. Now though, I think it’s time to take a short breather and maybe type in another BASIC program. I’m thinking Connect 4. I remember having that one typed in and added some Coco 3 hi-res graphics and sound to it.

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Gomoku BASIC ported to C

I have been thinking about game AI the last couple weeks, and since I’ve been working on a retro themed game for a retro Coco 3, an old book on BASIC games came to mind; Tim Hartnell’s Giant Book Of Computer Games. Tim was a self taught programmer and the author of several successful books on computer programming.

A few nights back I couldn’t sleep, so I decided it would be relaxing to type in a program from Tim’s book. My first choice was Reversi, but there was either an error in the printed source, or I miss-typed something and the program just wouldn’t run. My second choice was Gomoku, which ran the first time I typed RUN. The game has a strong defensive AI, but not much on the offensive side. I’m thinking it would be fun to work on that part of the AI. But that’s for another post.

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Compressing Bouncy Ball levels

The levels in Bouncy Ball are not all that complicated to store in memory. But they are taking up a bit of memory, which is a bit of a concern if we don’t want to have to resort to reading the levels from disk. With some simple compression, I have been able to shrink a level from 5880 bytes to 870 bytes. That’s a 6:1 ratio, or over 6 times smaller!

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Bouncy Ball Demo Video 1

Published my first demo video of Bouncy Ball just in time for Xmas. I decided to make it xmas themed after hearing about another Coco coder, John Linville made a game called Xmas Rush. It had evil snowmen that you had to save xmas trees from. That also helped me figure out what my story line would be. Since John was busy saving the trees in the forest, the evil snowmen stole everyones xmas trees from their homes, and brought them back to snowman’s land.

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