Convert an Apple II into an Apple 1 using MCL65+

This project uses the MCL65+ to convert an Apple II into an Apple 1!

Project code is on GitHub: https://github.com/MicroCoreLabs/Projects/tree/master/MCL65_Apple1

The MCL65+ is a drop-in replacement the computer’s MOS 6502 which can emulate the microprocessor and much more.

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

The MCL65+ uses a Teensy 4.1 to emulate the 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,

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.

Here is the MCL65+ inside of the Apple II Plus:

Here is a short video demonstration of the project:

To save time I pre-populated BASIC into memory location 0xE000 and also the Apple I anniversary program into 0x0280.

Here is a short BASIC programs which I downloaded over the UART:

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!