zxpi

This is a small experimental project connecting a ZX81 computer to a Raspberry Pi via serial interface. The project mainly uses Python3 on the PI but also uses Z80 code for interfacing (ZX81 as terminal). It can demonstrate things like loading of ZX81 programs, low-res-camera and internet usage.

The project is in a very early stage.

Getting started

First part is about preparing the Raspberry Pi. It is written for the Zero W(H), other models may differ in terms of what is needed to configure the serial port.

Configuration of your Raspberry Pi and installation

This project uses the GPIO serial interface of the Pi. For the Pi Zero W(H), this port is initially used by the blutooth interface, and thus we have to change the configuration a little. Assuming nano as an text editor:

sudo nano /boot/config.txt 

In the configuration, the following lines have to be changed or added:

dtoverlay=pi3-disable-bt

enable_uart=1

Also, the serial console needs to be disabled in the configuration. Afterwards, a reboot is required to apply the changes

Installing the project

First, make sure your Pi has access to the internet. This allows to just use git to get the latest version.

Make sure that the following packages are installed (they usually come with most standard distributions):

• Python >= 3.5
• Python packages (use pip install or pip3 install if needed)
  • serial
  • picamera (if you have a camera connected)
  • numpy
  • requests
• Git
• rng-tools (e.g. version 5-5-1) is needed for a (low entropy) raspberry pi without keyboard and mouse

Okay, now for the project itelf. In the home directory of the piuser

mkdir zxpi

cd zxpi

git init

git remote add origin https://github.com/holmatic/zxpi

git pull origin master 

This should create the zxpi project. It is started by

cd /home/pi/zxpi/src

python3 main.py & 

Auto-start

If you want it to auto-start the Raspberry Pi side of the software

sudo nano /etc/rc.local 

And add the start command at the end (but still before exit)

cd /home/pi/zxpi/src && sudo -u pi python3 main.py & 

The Zeddy side

On the ZX81, just enter LOAD "" (on a ZX81NU, use LOAD "-")

If the Pi is running and all connected, the main menu should show up.