Hi, I’m glad you’re interested in my project of adding Ultima IV support to my home brew 6502 computer. In this video, I’ll show you how I plan to achieve this ambitious goal, and what progress I’ve made so far.
Ultima IV is a classic role-playing game that was released in 1985 for various platforms, including the Apple II. It is widely regarded as one of the best games of all time, and a pioneer of open-world and moral gameplay. I’ve always wanted to play it on my own custom-built 6502 computer, the ebadger6502, which is based on the MOS Technology 6502 microprocessor, the same one used in the Apple II.
To make this possible, I’ve divided the project into four phases:
Phase 1: VGA Apple II graphics. In this phase, I’ll modify my existing VGA adapter design to better support the high-resolution graphics mode of the Apple II, which is used by Ultima IV. I’ll also examine the possibility of supporting the low-resolution color mode, which is used by some other games. I’ll rebuild the VGA adapter on breadboards and hook it up to my N-1 CPU board, which is a simplified version of the ebadger6502. I’ll update the schematics as I go along, and test the graphics output on a monitor.
Phase 2: Mockingboard. In this phase, I’ll build a sound card that is compatible with the Mockingboard, which is a popular sound card for the Apple II. The Mockingboard uses two AY-3-8910 sound chips, each capable of producing three voices of sound. I’ll use 2 of these chips to create a 6-voice sound card for my ebadger6502. I’ll build the sound card on breadboards and test it with some software that I’ll write or port from existing sources. I’ll also include the Mockingboard circuit into my schematics.
Phase 3: Computer updates. In this phase, I’ll make some changes to the ebadger6502 computer itself, to make it more compatible with Apple II software and more capable in general. I’ll emulate some of the soft switches that control various aspects of the Apple II hardware, such as graphics mode, speaker output, and keyboard input. I’ll fix the SD card interface in my design, which currently has some issues with level shifting and reliability. I’ll add support for banking ROM and RAM, which will allow me to switch between different memory segments at runtime. This will emulate the functionality of the Apple II Language Card (LC). I’ll produce a new PCB with all these changes, populate it with components, and test it thoroughly.
Phase 4: Port Ultima IV software. In this phase, I’ll finally port the Apple II version of Ultima IV to run on my ebadger6502 computer. I’ll update the SD card and DOS routines as necessary to load and save game data. I’ll emulate some of the floppy disk routines that are used by Ultima IV to access game files. I’ll use my software emulator as a debugging tool to help me with the porting process.
As you can see, this is a very challenging and exciting project that will push my skills and knowledge to the limit. But I’m confident that with enough time and effort, I’ll be able to achieve my dream of playing Ultima IV on my own 6502 computer.
I hope you enjoy watching this video and following along with my progress. If you do, please like, share, and subscribe to my channel for more updates. And if you have any questions or comments, feel free to leave them below or contact me through my website.
Thank you for watching, and stay tuned for more!