I have always wanted to build my own computer ever since i was a little boy, I just didn’t know how to. After watching the ben heck show where he built a replica of the Apple 1 computer, I took it up as a challenge to build mine too and even design a Printed Circuit Board for it. 

The Apple 1 is a computer built by Steve Wozniak in the 1970s and what served to launch the Apple Computer Company and generated an outburst of innovation that revolutionized the way people use computers. It was because of the history behind this computer that made building it a very exiting challenge. I also thought it would be fun to replicate most of the old chips with a new, more capable chips and increase the RAM size of the computer. 

At the heart of the Apple 1 is the processor, the 6502 processor, which is the brains of the operation. The ROM is where i stored the Monitor program and also the Basic interpreter and assembler. The RAM is used to store user programs and data. I also used a parallax propeller microcontroller to  handle all the i/o including video, serial and PS/2 port. When the computer boots, it runs the Monitor program and outputs a command line prompt to the screen and the user can start entering programs in 6502 machine language.

In order to enter into the BASIC interpreter, the user will type in ‘E000R’ in the Monitor and press enter on the keyboard. The user can then start to write programs in BASIC. In order to enter into the Krusader assembler, the user will type in ‘F000R’ and press enter on the keyboard. The eagle schematic and pcb files can be found here. Here are pictures of the apple 1 running the apple anniversary program: