The Homebrew Apple ///

Hi there. This blog is about my efforts to build my own Apple /// computer from as many existing parts as I already have. I cannot guarantee success with this project, regular updates nor even a conclusion. However, I will do as much as I can to document whatever progress I make toward a finished product so that others can gain some valuable info in the pursuit of their own 6502-based microcomputer.

I started this blog almost 2 years ago. Because I’m a busy guy with no time for hobbies, it’s taken me a lot of time to gain the knowledge needed to put together my own Apple /// compatible machine. I have re-written this blog many times. That is to say, rather than go back and edit posts with new information, it’s sometimes better to just take a few gallons of gasoline, light a match, and let physics take over. Thus, all 2 or 3 readers who had wandered in off the information superhighway by mistake will notice most of the other posts are gone. But I’m hoping this will result in more useful information and less pontificating.

Background:

I’ve considered diving into a homebuilt 8-bit computer project for a while. A project like this would allow me to scratch a long-time itch to learn some electrical engineering skills. My last formal education with EE was in high school 30+ years ago. In the last few years, I’ve become an Apple II aficionado. So it’s natural that I’d want to build a 6502-based system.

As part of my research, I’ve looked at other 8-bit homebrew computer projects such as Quinn Dunki’s awesome Veronica and Dirk Grappendorf’s 6502 Home Computer project. They aren’t exactly step-by-step how-to guides, but rather diaries of their respective development efforts and accumulated knowledge. Over the course of this project, I’ve also read and viewed a lot of other information online. So much so, that I believe one could acquire the equivalent knowledge as that of a cut-rate engineering degree.

I need to emphasize that I am not a trained electrical engineer. My knowledge comes from researching topics specific to a particular issue in my design. Therefore, I admit I do not speak with a truly educated and experienced voice. Rather, I am putting together a culmination of the research I’ve done and outlining what I’ve accomplished through tests. I’ll be sure to note things that I think a novice would need to know, as I would have liked to have known reading this blog if it were written by someone else.

Why an Apple ///?

As a result of my interest in the Apple II, I’ve become fascinated with early Apple Computer history and the systems developed during that early timeframe. The /// was a result of fear that the Apple II would soon become outdated and replaced by other computers, including the (at the time) rumored IBM Personal Computer. The PC industry was uncharted territory at this time and no one had experience with how the cycles worked in this new market. It was the Wild West of the Microcomputing world.

Therefore, Apple engineers rushed to design the /// as a system rather than a single-unit microcomputer focused around the 6502. It included such revolutionary features as bank-switchable memory and movable zero-page, a 6-bit DAC audio, built-in 80 column support, advanced graphics capability, and swappable character sets. Other features such as modular hardware device drivers and directory paths implemented in the operating system, are features carried over into the personal computers of today.

Most who start out on these sorts of single board microcomputer learning projects begin with a very simple design – more of a proof-of-concept than a fully featured working machine. Because of the complexity of the ///, I’m going to start my development with simpler designs which I can learn and build from so that other readers with similarly limited knowledge in microcomputer design could potentially build their own machine.

This won’t be an exact copy of the Apple /// or its motherboard. Instead, I will update several components with more modern equivalents – mainly power supply, SRAM memory over DRAM, and the capability of using solid-state storage devices. I came up with the idea of creating a portable, slimmed down Apple /// – similar to the Apple //c being a compact Apple //e. Having this end product as a target will help me define my project goals and give it a definite sense of purpose.

That, and the idea of a ///c computer is totally freakin’ cool.

apple_iii_c
Introducing the Apple ///c – the computer that could have existed in an alternate universe where the Apple /// actually succeeded the Apple II.
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