Monday, October 10, 2016

The replica projects: Mimeo and Replica 1

The first Apple-1 Replica project that I have found is the Mimeo project. This is a reproduction of a real Apple-1 board, where you have to solder real vintage parts. The result is a real clone of an Apple-1.
Mimeo Apple-1 Replica board
Mimeo 1 assembled board

This is a very cool project, and even you need an electronic background to assemble and test it, at the end you have a real clone almost identical to the original hardware.

The second Apple-1 replica project is the Replica 1, a bit different from the previous project in the use of the components.

Apple-1 Replica1 board
The Replica 1 board

This is very interesting because here we have almost the same main components used in the original board such as the Motorola 6502, logic ports, Memory chips etc. But, for specific tasks like the I/O, handled by the PIA or the video terminal, we have a Parallax Propeller that does everything. I could call this not a real clone but a hybrid clone.

Now, there isn't really the right choice between these projects. I was interested in both of them, but at the end the challenge of building something is to start from scratch. I thought a third way. Since I have some experience in programming microcontrollers, I started to check if I could have created an emulator for a development board like Arduino. This choice leaves most of the work to the software coding, but you have also the chance to easily update the firmware without changing the hardware.

I didn't take in consideration the use of FPGA chips because this technology even if it's more suited for replicating a real hardware, it's very hard to configure, set and program.

So the work started with the first important question: How does a real Apple-1 work?