Arduino Due CP/M Personal Computer

For the sake of completeness, I've created a new wiring diagram.  It's neater and includes the LEDs and reset switch.

As per the last project log, I've moved the internals to a larger enclosure.

Inside...    plenty of room for future projects...

Connected up to a Pi acting as a terminal via minicom...

That's all folks!

This project for an Arduino Due CP/M Personal Computer is complete.  People should be able to follow what I've done to make a low-cost CP/M computer without too much effort, which was the goal.

..but I have some ideas for the future..

Software:

For a while I also added a fork of Tiny BASIC and I shared the code with a few interested people.  This meant the computer started up in BASIC and CP/M could be booted with a 'cpm' keyword.  But any further development of that idea is beyond the original goal for -this- project, so I will create a separate project for that in due course.  The BASIC allowed saving files into CP/M's drive B: and provided an autoexec function via a autorun.bas file.  It also featured some ANSI colour and block graphic support.

I've also experimented with a menu system to provide some simple organisation tools, such as a calendar, address book, card file, calculator, editor etc.  I'm looking at how the text versions of DeskMate worked on the TRS-80 Model III, the UI on the TRS-80 Model 100/200 and the Locoscript software on the Amstrad PCW8256.

At present the computer is a black box with a USB cable, requiring another machine with USB to power it and communicate through a terminal.  I am interested in developing it into a standalone computer, again this would be a new project beyond the scope of this one.

The RC2014 Z80 computer can use a Pi Zero as a £5 graphics card.  It boots pigfx - a bare metal solution to drive a HDMI display and USB keyboard.  It supports an ANSI terminal and has some support for colour graphics.

https://hackaday.io/project/9567-5-graphics-card-for-homebrew-z80

https://github.com/fbergama/pigfx

There are a few changes I made to the standard RunCPM.  It is easier for me to describe them than fork a copy of Marcelo's code.

Since the Power LED connected to Pin 12, I added the following define:

#define POWLED 12

In setup() I added the following to light the Power LED:

pinMode(POWLED, OUTPUT);
digitalWrite(POWLED, HIGH);

I also set the serial speed to 115,200:

 Serial.begin(115200);

I altered loop() so the LEDs blink alternately after CP/M exits:

void loop(void) {
 digitalWrite(POWLED, HIGH);
 delay(500);
 digitalWrite(POWLED, LOW);
 delay(1000);
 digitalWrite(LED, HIGH);
 delay(500);
 digitalWrite(LED, LOW);
 delay(1000);
}

Power LED:

Disk LED: