Computers Overview
Commodore PET
Sinclair ZX80
Sinclair ZX81
BBC Micro
Sinclair Spectrum
Memotech MTX
    About
    Library
    Manuals
    Options
        Disk Systems
            FDX
            HDX
            SDX
    Photos
    Projects
    Repairs
    Software
    Tools
    User Groups
    Video Wall
Memotech CP/M
Atari ST
DEC 3000 AXP
OpenVMS
Raspberry Pi

 

 
 
 

The Memotech MTX Series

MEMOTECH  DISK UPGRADE

This is a work in progress - to be continued . . . .

 

Background

The floppy disk drives and media used in the original MTX disk systems are becoming increasingly unreliable and no longer suitable for day-to-day use. Although there are a number of modern day alternatives available, such as my CFX systems (Compact Flash) and Andy Key's REMEMOrizer (SD Card), legacy Memotech disk based systems really need drop-in replacement disk drives.

I have had good results using both internal and external HxC floppy disk replacement devices, but they are not cheap and cost more than many MTX'ers are prepared to pay. However, there is an alternative . . . .

The image at the top of this page shows a floppy disk drive emulator, I think it was originally designed by Gotek in India. These drives were designed to replace the 3.5" 720k/1.44MB drives found in PCs, industrial machines, music synthesiers, etc. and are readily available from eBay and the like, typically costing between £12 and £20 (as of March 2018). The firmware supplied with the drives is locked down and provides only basic PC type compatibility. Around 2014, Hervé Messinger developed replacement firmware that allowed the Gotek to be used in a Commodore Amiga. The firmware was released into the public domain and soon started to appear loaded onto Gotek hardware on eBay and various retro computer sites in contravention of Hervé's stipulation on his site that the firmware should not be installed on pre-flashed devices. Unfortunately, this led to Hervé ceasing to develop his firmware. Since then though, others have developed replacement firmware to allow the emulator to replace floppy disks in other retro computers, including the Atari ST; Jean-François Del Nero has even released a commercial version of his HxC firmware than runs on the Gotek (the license cost is 10 Euros).

More recently, Keir Fraser has developed another firmware solution, described in his Project History on GutHub: "The FlashFloppy project was begun as a Free and Open Source replacement for the abandoned free Cortex firmware. . . My aim then was to implement a more capable Gotek firmware, . . . compatible with a wide range of host systems." After lying dormant for a couple of years, Keir's project kicked off in earnest in mid 2017 and at the time of writing (March 2018) has progressed to the point where the firmware is capable of supporting many Shugart compatible drives and is compatible with disk image formats such as RAW and even HFE (the HxC format).

 

   
In addition to supporting the basic interface of the standard Gotek device, including a 2 or 3 digit hex display and Up/Down buttons, FlashFloppy also supports a range of additional hardware modifications, including an LCD or OLED display, a rotary encoder for scrolling the selected image and an piezo sounder to emulate disk stepping.

An example of a "fully loaded" FlashFloppy device is used as the Flash-Floppy Facebook Group photo.
I bought a Gotek from a Chinese supplier on eBay UK for £12.05 (March 2018). To match the Memotech hardware, I opted for a black one.

This photo is from the eBay listing, as you can see, this unit includes a 3 digit hex display but I will be replacing it with an OLED display.
It seems that the OLED most commonly used is a 0.91" (128x32) display, so I bought one of these from AliExpress for £1.75. The FlashFloppy firmware allows the usable display area to be restricted to the size of the Gotek display cutout, this will be neater than trying to enlarge the cutout.
I bought 5 of these piezo beepers from an eBay UK vendor for £2.89

They have short lengths of wire attached, but for connection to the Gotek header pins, I spliced on additional wires terminated with Dupont connectors.
A bare rotary encoder can be used, but the most common implementation seems to be to use a KY040 module which has an attached PCB.

They are plentiful and cheap on eBay, I bought a pack of  6 from another Chinese eBay UK vendor costing £2.61.
The FDX used 5.25" drives, so I purchased a 3.5" to 5.25" adapter from another Chinese eBay UK vendor costing £2.12
The PCB removed from the case.

The jumper positions at the top left (J3/J4) and centre bottom (JK) are shipped without pins installed. These need to be populated to facilitate connection of the ancillaries and to allow a jumper to be fitted when flashing the firmware.
With the jumpers installed.

Jumper "JK" will be inside the Gotek case, fitting an angled jumper, like the existing "J7" jumpers is the best option.
With the jumpers installed (although, some people just use a bit of wire jammed in the holes!), the firmware can be upgraded using the ST Microelectronics DfuSe program. (The software can be freely downloaded, but you need to register on the ST Microelectronics site.)

Instructions for flashing the Gotek firmware can be found on the FF Wiki. You can program it serially using a USB-TTL adapter, but the easiest method is to use USB programming, this requires a USB A-A cable.

The procedure is well described in this video.
At this point, I wanted to test the basic Gotek without any of the additional hardware modifications, so, with the firmware upgraded to the latest version of FlashFloppy (at the time of writing, v0.9.16a), I connected the Gotek to an FDX.

With the Gotek pinned for drive ID0 and FDX drive 0 set to Memotech Type 03 (DS/DD, 40 Tracks) I copied one of my existing HxC "hfe" Type 03 system disk images to the root directory of a blank USB stick and powered on the FDX. The system quite happily booted from the Gotek without any problems.

I copied a second disk image to the USB stick and was able to switch between them using the "Up" / "Down" buttons. The 3-digit display is adequate when there are only a few image files on the USB stick; when selecting a different image, the buttons are used to scroll between the images, when the required image number is displayed and the buttons are released, the display briefly flashed to show that a new image has been selected.

Hosts such as the Amiga and Atari ST have navigator software available that allows the disk images to be selected from an onscreen menu. For these machine, the 3-digit display may be sufficient, but for the MTX, it is not adequate, so an LCD or OLED display is a must. The next step was to try my OLD display.
The connections for the OLED display can be found on the FF Wiki page. (Image courtesy of Keir Fraser)

Again, connecting my OLED display worked first time.
I tested the display before I mounted it and the text is very clear (even with the protective film still on the display). Although only 0.91" wide, the display is more than adequate.
   
The encoder PCB is really a little too big for the Gotek case. I removed the encoder of the board so that it would sit nicely in the front panel. There was a pilot "dimple" in the cover which was in the perfect place for the encoder knob to be fixed and drilled through that point with a 7mm bit.
The connections for the encoder can be found on the FF Wiki page. (Image courtesy of Keir Fraser)

I removed the PCB and soldered wires directly to the terminals , the other ends had Dupont connectors fitted for attaching to the pin headers on the Gotek PCB.
   
   
At this point, I was able to read/write the Gotek with my FDX using the .hfe image files that I created with the HxC software for use with my HxC emulators. I think that I probably have most of the available MTX software in .hfe images but I also wanted to have the Gotek work with the raw image files that Andy Key's .mfloppy format uses.

FlashFloppy natively supports a wide range of image formats, including, Atari ST,  Amstrad CPC and Acorn  DFS/ADFS. It has pre-configured track layouts for some Raw Sector images, such as various music samplers, so I thought that adding Memotech formats should be relatively straight forward.

After providing details of the Memotech disk formats and Andy's .mfloppy images, Keir kindly added support for Memotech Type 03 and 07 images. Although FlashFloppy can handle longer file extentions, it works best with 3 characters and .img follows existing FlashFloppy naming conventions so we agreed that Memotech images would use this naming convention.

This is slightly awkward in that it means renaming Andy's .mfloppy file names, but this can be easily done in Windows using PowerShell. For example, to rename all of the files in the current directory, you can use the PowerShell command line :

        Dir | Rename-Item –NewName { $_.name –replace ".mfloppy-07","-07.img" }

This renames files in the form filename.mfloppy-07 to filename-07.img

I copied all of Andy's .mfloppy files in both Type 03 and Type 07 to the USB thumb drive, but in practice, only the single set of files that correspond to the FDX/SDX disk controller configuration are required. In most circumstances, you will want to configure the disk controller for an 80 track drive and use the Type 07 image files. In that case, you could also remove the format type from the filenames.
Here we are, testing the Gotek with the firmware upgraded to support .mfloppy type images as well as the "standard" HxC .hfe images.

The floppy drive emulator is connected to an FDX with the disk type configured for a DS/DD 80 Track drive. The FlashFloppy window shows the name of the currently loaded image - in this case, "SuperCalc_07" - my original SuperCalc disk, converted to a Type 07 .hfe image file. 
   
   
   
Cost breakdown 
Gotek £12.05
Display £0.91
Encoder £0.44
Beeper  £0.58 
Adapter £2.12
Firmware   Free !  

 

 

 
   

mailto: Webmaster

 Terms & Conditions