Greaseweazle – Flux level floppy disk tool

This page about the Greaseweazle is always being updated. Last update 7th June 2024.

What is it?

The Greaseweazle USB devices provide flux level read and write access to floppy disks. The device’s software is open-source and receives regular updates. More information can be found on the device’s GitHub wiki page. : Greaseweazle Wiki

This is the main piece of hardware and software I used as part of my floppy disk recovery and transfer service.

My Greaseweazle devices


Greaseweazle Blue Pill Side View
Greaseweazle Blue Pill Side View

I acquired my F1 board directly from the designer, Keir. Two types of boards were available: one with the standard 34-pin connector and another with the 30-pin Amstrad-style connector. So far, I have only assembled the version with the 34-pin connector. The assembly process was fairly straightforward, although it did require soldering some surface-mounted resistors.

For programming my STM32 device, I used a standard USB to TTL serial adapter. As an alternative, a ST-Link programming adapter can also be employed.

F7 Plus Rev 2

Greaseweazle F7 Plus Rev 2
Greaseweazle F7 Plus Rev 2

Purchased March 2021, the F7 Plus has a few additional features over the original F1 device I have. Extra features include

  • Jumperless Update
  • Multiple Drives – Allows simultaneous connection to two PC, or three Shugart, drives on a single ribbon cable. Useful for cased installations.
  • Write-Protect Jumper – Physically disables write capability, making it impossible to accidentally overwrite disks during preservation.
  • Buffered Outputs – Higher (40mA) output drive capability, needed for older floppy drives with strong input pull-ups (resistance <1kOhm).
  • 12v Power input – Allows board and drive to be powered from a single 12v power brick. These models are the only ones to directly support drives requiring a 12v supply; other models require such drives to be separately powered.
  • User Outputs – User-configurable outputs. Useful for non-standard control signals such as reduced write current (8″ drives).

What can they read?

Here is what I have done successfully with mine so far.

  • Written 5 1/4 disks for the Osborne 1 luggable computer
  • Written and read 3″ disks for use in the Amstrad CPC, the Amstrad PCW and the ZX Spectrum +3
  • Read and write 80 track 3″ disks as used on the Amstrad PCW 9512 (photo below)
  • Used the Amstrad DDI-1 external floppy drive. NOTE : If you plan to use yours with the Greaseweazle device, make sure you disconnect the 5v internally. Failure to do so may kill your Greaseweazle!
  • Written and read 5 1/4″ ADFS disks for the Acorn BBC computers
  • Written 3.5″ disks for the Commodore Amiga
3 inch drive and associated cales
Amstrad EME-232 80 track, double sided drive and associated cables

The software

The Greaseweazle device software is developed in Python, making it cross-platform compatible. While I primarily use the software on Windows 11, it is also operational on macOS and Linux. The software can be downloaded from the provided link. : Greaseweazle Downloads

Other software

There is another highly useful software for Windows that simplifies the process of reading and writing to your disks, particularly if you prefer not to use a command line interface. (I don’t mind the CLI interface, as I am accustomed to Linux.)


This was the first piece of additional software I found. GreaseweazleGUI is a Windows GUI wrapper for the python script running Keir Fraser’s STM32F1/F7 “blue pill” microcontroller widget.

GreaseweazleGUI v2.100

You can download GreaseweazleGUI from here: GreaseweazleGUI

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