fZ80 computer host and CP/M and MP/M software

28 Jan 2026

Most recent software versions

This page is mostly about how to do fZ80-specific software upgrades. If you are looking for CP/M and MP/M application software, WordStar, BDS C, SuperCalc2, etc, click the link.

The current software version is here. Please read the ReleaseNotes.

HOW TO SEE WHAT VERSION FIRMWARE YOU HAVE NOW

You will need to reset the machine to display the software version.

• Press and hold in the rotary encoder knob.
• Press and release RESET.
• When you see the "release push switch" message do so. What's in front of you now is the Machine Monitor, used for error recovery.
• The software version is displayed on the top line of the screen.

HOST SOFTWARE AND UPGRADES

Links to sections on this page.

Upgrading to new versions

Software is released as needed. Software changes are of two types, firmware and CPM or MP/M software. Most changes will be on the CP/M or MP/M side of things. Firmware changes require uploading code from a modern computer via USB cable to the controller inside the box, accessible by removing/tilting up the cover. This is inconvenient at best and I make every effort to minimize these. See the Firmware Update Steps, below.

The rest of the changes are to CP/M and MP/M programs and are generally as easy as copying in files and occasionally running an update program.

Performing updates

Refer to the ReleaseNotes file for the details on what has changed and how to do updates; often there is an "update kit" that simplifies things.

For all changes, it's good practice to save any work you've done. But also save any files you might have customized on your A: drive as the contents of A: will change.

Download the big release blob (ZIP file) and unpack it. It will create a folder named for the release and all that files will be in that folder.

To update an existing machine the process is generally as below; there may be specific details in the CHANGES document above.

• Download the full release, and any "update kit" ZIP file mentioned in ReleaseNotes. Unzip the update kit into a newly created folder.
• If there is a firmware update included, load the firmware into the Teensy using methods described elsewhere on this page.
• Format or empty a removable card, insert it into your modern computer, and drag all the files from the update kit folder into the IMPORT folder on the removable disk/SD card. Eject the card.
• On your FZ80, boot CP/M. Insert the SD card into the left slot.
• On fZ80, change to the C: drive (left slot). Run the import program to import the files you put into /IMPORT folder. A:IMPORT *.*.
• Use PIP to copy all these files onto your current A: drive, overwriting any existing files. You may have to remove all read-only permissions on A: using SET *.* [RW] first.
• Follow any other instructions in the ReleaseNotes document.

Firmware upgrade steps

• Connect a micro-USB cable to the Teensy 4.1's USB socket, and your computer. Flash the downloaded .HEX file using the Teensy loader or Teensyduino.

That's it. It should boot normally with all of the new features.

If you have other SD cards you've made bootable, be sure to SYSDUP each or otherwise update them.

Teensy Loader from PJRC.COM

The Teensy Loader does not involve the Arduino IDE in any way. Download and install the Teensy Loader from the PJRC Teensy Loader page. The loader talks to the bootloader built into the Teensy 4.1 via a USB cable from host computer to the Teensy itself (the Micro-B connector on the Teensy board itself; not the USB-C jacks on the rear of the fZ80 board).

Operation is simple: on the Loader program click open, open the HEX file downloaded from this site, and click program.

TeensyDuino (via Arduino IDE)

TeensyDuino is the common Arduino IDE with extensions provided by PJRC. The Arduino IDE can be either the mature 1.8x version (my preference) or the latest 2.x version (too many fluffy add-ons for me, and a small debug window). If you use Arduino IDE already just add Teensy support to it. If you don't use it yet, I suggest trying the 1.8.19 or whatever version, available for download from arduino.com and I think what Debian apt install delivers.

Installing Arduino IDE

The Arduino IDEs can be downloaded from the Arduino software download page. Aug 2025 note: Arduino.cc is enshittifying, pushing everyone online, and deprecating the well-behaved downloadable tool. I may put up download copies... Jun 2025 note: it was surprisingly difficult to find this link on the arduino.cc main page! All the way at the bottom! Arduino appears to be heading down the sadly-common path of enshittification.

Arduino pushes the (currently) 2 version. The "Legacy IDE (1.8.X)" is further down the page.

With the Arduino IDE installed, follow the simple instructions on the PJRC TeensyDuino page to install the TeensyDuino extensions. the first link there.

Files

• fZ80 software and document release browsable folder