0110 – Timing is everything

Before I get much further with the video module, I need to properly flesh out the heartbeat of the system: the timing circuit. As mentioned previously, the /// uses a 14.318MHz clock. The reason for such a high  frequency is that (apart from other components in the system) the video module needs a 7MHz and…

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0101 – Video output

Now that I've completed a basic 6502-based computer, my next milestone is to implement a video output system. The Apple ///'s video system was unique, in that it provided similar video modes to the Apple II, as well as additional modes to display higher resolutions with many more colors. Additionally, unlike the II which was…

0100 -Milestone 1: a running program

Today marks the completion of my first milestone: running a program in ROM and keyboard input/ display output through the ACIA to USB-serial bridge. A happy day to say the very least. Another "Hello World" of a fully-functioning computer. Once wire wrap was completed (and failed, then troubleshot, rewrapped, repeat...), I began the task of…

0011 – RAM and I/O

Getting to the free-run stage is easy. Where it gets complicated is when you add hardware to make your fancy program counter into a real computer. When you're doing a project like this, its assumed you are willing to put in the time to learn some electronics in order to move forward. Both the journey…

0010 – Free Run and Hex Display

The first test of every new microprocessor  "single-board" project is free-run. Once the CPU, clock, and reset circuitry is in place, we hardwire the data bus to supply the data pins on the 6502 with its opcode NOP (No-Operation). The hexadecimal for the NOP instruction is $EA. This is a simple do-nothing opcode that basically…

0001 – Clock and Reset

Let’s start with a clock and reset...

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…