You will need a working copy of raspian install on your raspberry pi. If you need help getting an image on you pi click here

Once the pi you need to download the CP/M Emulator software

Open a terminal and Download the software

$ git clone https://github.com/jhallen/cpm.git

Then Compile the software

$ cd cpm $ sudo make

Run the software

$ ./cpm

You should get an a: promtto exit type bye

The software which we downloaded is a cp/m emulator you can read more about here

I downloaded some software from www.retroarchive.org/cpm/ and then copied into the cpm directory.

We need to set the PI to boot automatically in to the cpm emulator

Edit the bash file

$ sudo nano /home/pi/.bashrc

Add these to lines to the bottom of the file

echo running at boot sudo cpm/cpm

Next Up is the screen it requires a custom display mode due to the resolution been non-standard

Edit the config.ini

sudo nano /boot/config.ini

Add these lines to the bottom for the file

max_usb_current=1 hdmi_group=2 hdmi_mode=87 hdmi_cvt 800 480 60 6 0 0 0 hdmi_drive=1

Also I edited the same file and changed the overscan so I got a 4:3 aspect ratio

overscan_left=32 overscan_right=25