This project uses my MCL65+ to replace the Apple II’s processor and convert the machine into an Apple 1.

The MCL65+ is a drop-in replacement the computer’s MOS 6502 which can emulate the microprocessor and much more.  It uses a Teensy 4.1 to emulate a cycle-accurate 6502, the Apple I PROMs( which contain the famous 256 byte Woz Monitor), 8 KB of RAM, and a few conversion routines for differences in video display and keyboard handling between the two computers.

The Apple II BIOS is replaced by the Woz's Monitor, so the machine is quite effectively running as an Apple 1.

All keyboard and video I/O are also echoed to the Teensy’s UART so that code could be downloaded to the Apple 1 by simply cutting and pasting it into a terminal program.

To save time I pre-populated BASIC into memory location 0xE000 and also the Apple I anniversary program into 0x0280. I demonstrate running both in the YouTube video.

The Apple I Operation Manual contained a small program to print ASCII character across the screen, so of course this was the first thing I tried when bringing the system up!

So, this project is for those of us who would like their own Apple 1 which uses all-Apple hardware and software.

Source code is on GitHub