A Gotek drive; A USB A to USB A cable (make one if you don’t have one to hand) Software from ST Microelectronics; 2 jumper leads or appropriate way to connect pins on the Gotek. The USB A to A cable is not a common cable: it is literally every pin connected from a USB A plug to another USB A plug.

After getting annoyed at the failure rate of my old 3.5' floppy disks I started using a Gotek USB Floppy emulator on my Amiga and Atari ST. Being impressed with how well that worked I decided to give it a shot on my trusty ZX Spectrum +3 who's disks are as equally unreliable, even harder to source and also very expensive.
On my other Gotek drives I use the FlashFloppy firmware (still in active development at time of writing v0.9.27a - Aug'18) and recent developments have included .DSK support for the Amstrad CPC & Spectrum +3 (basically the same format). Therefore as a test I mocked up some connectors (as described here), plugged it all in and got it running nicely with compatibility at 100% of the disks I've tested. A list of the TOSEC collection tested disks can be found here. I've also written a small utility which removes the need to re-dump the weak sector protected disks by adding this extra information to the eDSK automatically. You can download a Windows executable here or follow the instructions detailed on the FlashFloppy wiki here.
I was impressed enough to decide to permanently replace the internal drives of a couple of my machines, including creating a 3D printed drive caddy as the Gotek case won't fit in a 3' drive bay. Also as there is no file-selector for the ZX Spectrum I added a rotary encoder with OLED display to navigate the files on the USB stick, and topped it off with a sound buzzer to emulate the sound of the original drive.
Below is a guide on how I built all of this, heavily utilising the resources of the web, including the parts I used and links to the 3D printed caddy I designed so you can print your own.
A lot of the information below is from the FlashFloppy wiki so I highly recommend you read that to get more information and more detailed schematics.

Storage Upgrade Options

'Floppy Disk'

'Floppy Disk' Emulation

Although the Amiga may have a hard disk (real or emulated) installed, a floppy disk is still needed to run much of the Amiga software that was written to run only from, often a bootable, floppy disk. Even though you may have the original floppy disk media available, it is likely to be 25 to 30 years old and will become even more prone to failure as time goes on, not to mention the long term reliability issues surrounding mechanical floppy disk drives. What is needed is a reliable way to emulate a floppy disk, that allows the Amiga to boot from it and appear to the system to be a 'real' floppy disk.

This page contains details of two solutions that I know work, there may be others, but the devices on this page are enough for me.

HxC Floppy Disk Drive Emulator

• Copying Workbench on the 2000.
• The standard firmware on the Gotek is not very useful, but luckily there are alternatives. First there is the HXC firmware. This costs 10 euro and allows the Gotek to read HXE images from the USB flash drive. DSK and DMK images can be converted to HXE with the included tool. Alternatively there is the open source FlashFloppy firmware.

The HxC Floppy Drive Emulator is a Universal Floppy Disk Emulator, developed by Jean-François Del Nero (Jeff). It began life as a way to emulate the 3.5' disk drives on Atari ST and Commodore Amiga computers and has developed into a solution that can replace floppy disk drives in a wide range of computers, music samplers and a range of industrial machines - in fact, just about anything that has a floppy drive interface.

There are two main kinds of HxC :-

• A USB version which allows connection of the floppy disk drive interface of the target hardware to a PC via a USB cable.

• An SD Card version which emulates floppy disk drives with disk images stored on an SD card

Full details of the HxC Emulator can be found on either

• The HxC 2001 Home Page - Jeff's site, or

• The Lotharek's Lair Site - Przemyslaw Krawczyk's (Lotharek) site (Lotherek manufactures the hardware)

I have already purchased an HxC Emulator for use with my Memotech computers, an expanded description and pictures of the different HxC form factors can be found on my Memotech FDX disk upgrade page. The photo above is of the type 'F', this has a form factor the same as standard 3.5' floppy drive, external devices are also available as well as a 'headless' model with no user interface - the user interacts with the drive using a custom software interface which is available for, Atari, Amiga and Amstrad CPC computers.

The HxC is a very good and flexible deign, well suited to use with a range of hardware, however, as the table above shows, it is significantly more expensive than the Gotek emulator.

Gotek Floppy Disk Emulator

Background

The Gotek Floppy Disk Emulator is designed to replace floppy drives of various formats in devices using PC compatible floppy drives. The hardware is quite simple, consisting of a single PCB, at the heart of which is a 72MHz ARM Cortex M3 based STM32 MCU which translates image file data into floppy disk track & sector format in real time.

Development

Gotek only write firmware to support PC formats, but it is possible to re-flash the MCU with replacement firmware, currently, the only 'available' option is for the Amiga - Gotek emulators re-flashed with Amiga compatible firmware are being sold by quite a few vendors on ebay. These devices have been very popular with Amiga owners and I was recommended to get one of these to replace/supplement the FDD in my Amiga A1200.

Provenance

I was all set to buy from one of these ebay vendors when I came across the origin of this great piece of programming - it was created by Hervé Messinger, without reverse engineering or otherwise copying the Gotek firmware, Hervé created his own firmware that can emulate the custom, non-PC compatible, disk format of the Amiga range. Hervé has generously made the binary (but not the source) of the firmware available for free download on his blog 'Transform the Gotek Floppy Emulator into an Amiga Floppy emulator', but has placed an entirely reasonable condition on it that 'software provided on this page can’t be sold directly or indirectly into a pre-flashed device'.

This presents us with something of a moral dilemma, leaving aside the unscrupulous ebay box shifters who are out to make a quick profit, a few Amiga users have re-flashed Gotek drives with Hervé's firmware and made them available to other Amiga owners, making a small charge for the service. There is no doubt that some Amiga owners would not be happy to undertake this fairly simple procedure (fully described on Hervé's blog) and although providing this service could be viewed as a purely altruistic act, it is expressly forbidden in Hervé's blog.

Current Status

There is an extensive trail of comments on the blog that makes it obvious that Hervé has become a bit disillusioned by the sale of drives with his firmware on them, to such an extent that development of the firmware has, if not totally stopped, at least stalled.

Hervé was not charging for the firmware and made it available as a free download, OK, although maybe he should have included some sort of license with it, it is clear that people are profiting from his good work and, as a result, the firmware has not been updated since 30/03/2014 - though it is still available for download. Whilst the current version of the firmware appears to be stable, it's still a beta version and has probably been further developed since the last release. It is unfortunate, but understandable, that we are unlikely to see enhanced firmware until Hervé creates a new licensing model that he is happy with - assuming that he even wants to.

Impact

What does this mean in practice ? Well, I guess it comes down to an individual's personal choice, although the drives are available for purchase with the re-flashed firmware, I have decided that for me, I prefer to adhere to the constraint placed on Hervé's blog and purchase a standard Gotek and re-flash it myself. I would encourage others to do the same. As well as giving you that nice fuzzy feeling you get when doing something that you know to be right, you will also save money - the cost of a standard Gotek on ebay (I paid £12.95 including P&P, with another £1.50 for a USB to serial converters) is about half of what I have seen the cheapest of the pre-flashed drives sold for.

Next : Interfacing to the Amiga

F&f.hu

Also : Amiga floppy disk interface - signal descriptions