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The Memotech MTX Series

Memotech Photos

 

Here you will find a selection of pictures of the Memotech series of computers and add-ons. Click on the photo to open up the original file. The photos towards the bottom of this page were taken by me of my Memotech kit.

To keep this page to a manageable size and to minimise the download time, there are links to additional pages where you can find more detailed photos of particular items, including these pages :-

If you click on the images below, the full size picture will open, be aware, many of these are quite large and may be unsuitable for display on mobile devices or with a slow internet connection, but I wanted to include as much detail as possible in the larger photos.

 

   
Photo from the MTX brochure showing the MTX, FDX, DMX80 printer and what I think is a Microvitec Cub colour monitor.

You couldn't actually set the kit up as arranged in the photo, the FDX ribbon cable to the MTX was about 4" long!

The DMX80 Printer.

A colour coordinated, 9-pin, dot matrix printer, manufactured by Panasonic based on the Panasonic KX-P1090.

Software compatible with an Epson MX80

Power Supply

The PSU is actually just a transformer, as printed on the case, it delivers 22.5vac with taps at 18v and 9v, smoothing. voltage regulation, etc. is done on the MTX circuit board.

The MTX manual does not include drawings for the PSU, but another user "Mark" (1024MAK) has posted this sketch of the DIN power plug pin-out at this Sinclair ZX forum thread.

I have created a separate page giving details of the PSU design & operation.

Photo courtesy of David Kimberlin-Wyer

A poor quality photo (cropped from an advert on ebay.uk in 2013) showing another style of Memotech PSU label, you can just make out that it was a common PSU for the MTX500, 512 and RS128 computers.
PSU supplied with a MTX512 sold on eBay UK in 2017, possibly for the US market, this late model PSU includes details of the 18V (0.82A) and 9V (0.28A) AC current consumptions, in addition to  the 22.5V (1A) rating.
A later version of the PSU with a Memotech Computers Ltd logo, the company started by Geoff Boyd after the original Memotech Computers folded.

I think this PSU was released with the MTX512 Series 2 as the logo matches the Series 2 label.

The case design and output voltages are the same as those of the original Memotech PSU - it is just the label that has had a makeover.

Power Supply internal photo.

This photo, and the internals sketch were found on the same thread. "Mark" has also drawn a sketch for a proposed replacement PSU. The thread also lists some possible components to build the replacement PSU.

 - use this information at your own risk obviously!

The Memotech Speculator

An add-on that allowed a limited number of ZX Spectrum games to be played on the Memotech. You can find a couple of reviews on the Articles page.

The larger photo is from Jim Wills' website.

A couple of Speculator photos - courtesy of Tony Brewer himself!

The Speculator PCB was profiled to fit inside a "standard" Memotech "ROMPAK" case. The photo shows a "ROMPAK" with a generic label but the finished version was identified with a "Speculator" adhesive label.

Another Speculator photo - courtesy of Tony Brewer

As described in the reviews on the Articles page, the Speculator is made up of two custom PALs, a 2K memory chip (Hitachi HM6116P-4 200ns SRAM) and  a couple of standard logic chips, a 74LS123 (dual monostable multivibrator) and a 74LS74 (dual flip-flop).

Technical details of the Speculator design can be found on the Speculator page.

Thanks to Martin Allcorn, I now have my own Memotech Speculator

- complete with "production" version of the Speculator case

Reverse side of the Speculator ROMPAK

Removed from the case, the component side of the Speculator PCB
And the solder side
The Memotech branded "Computer Program Data Recorder"

 

This appears to be a Memotech branded version of the Morwood Data Recorder . This was reviewed in ZX-computing from Aug-Sep 1984. I found a copy of this article on-line at www.freetimeweb.nl

 

A copy of the review is available here in the Library pages

 

 

Photos courtesy of Dave Hickman

 

Dave's Photos  (the full size images are quite large)

MTX Computers

MTX512 bought from ebay in 2012

In reasonable condition but has a slight blemish on the keyboard label, it is fully functional, but the keyboard is fairly "sticky".

Internal view of an MTX500 with a version 4000-04 computer board.

The 25-way "D" connectors on the right are for connection to the RS-232 board (not shown). The RS-232 board was an optional extra and included the interface to the FDX.

Close up of the MTX500 main circuit board, version 4000-04.

The silver box at the top is an Astec 1286 UHF modulator and the inverted circuit board below it is the video board.

The MTX main circuit board, with the major components identified. Most chips are used to perform discrete functions, some of the multi-input, basic logic chips, e.g. AND gates, are used by a number of circuits.

This board is a "4000-04 Computer Board", fitted with 32KBytes of RAM, i.e., from an MTX500.

My "MTX512" that only had 32K of RAM.

Now upgraded to 512K with one of Andy Key's MTX Memory Cards. Read about the trouble I had before I got to this elegant solution here.

The revision 4000-05 circuit board from my "MTX500" with the 80 Column board.

The board actually has 64k of RAM, so is actually a MTX512 board.

You can see the 80 Column card soldered to the internal edge connector.

The revision 4000-06 circuit board from an MTX512 from the USA.

The black and red cable plugged into the back of the video board are for the external TV channel seletor

Video Boards

This is the Video Board from the UK version of the MTX.

The board is plugged, component side down, into the motherboard via the two brown header plugs on the top and bottom of the board.

The BNC connector for the monitor and the phono connector for "Hi-Fi" on the rear panel are taken off this board via a plug which connects to the 4 pins on the J12 connector at the bottom left hand side of the board.

This is the Video Board from the US version of the MTX

The most obvious differences are the absence of the CD4013 in the upper left corner and the replacement of the 4.434 MHz PAL crystal with a 3.579 MHz crystal for NTSC.

Solder side of the NTSC Video Board

The two pin header is only fitted to the US version of the board and is connected to the switch on the rear panel which was fitted to US models and used to select between TV channels 3 &4

Rear panel of the MTX, showing the NTSC channel selector switch
The US version of the MTX with the NTSC Video Board was fitted with a different model of UHF modulator, an Astec UM 1285-8
An unusual view of the power regulators and power transistor located below C56, the large electrolytic capacitor at the rear of the MTX computer board, which normally obscures these components.

In this photo, the video board and C56 have been removed prior to the replacement of C56.

Photo courtesy of David Kimberlin-Wyer

Expansion Boards

The RS232 Communications and FDX System Interface Card

The blue edge connector attached to the internal expansion connector on the main board. The connector pins for the 25-way "D" connector plugs is shown on the left.

The IDC connector header shown at the top is the interface to the FDX Disc System. I know of a limited number of boards that did not have the DART or other RS232 chips fitted and only supported the FDX interface. (see below)

The solder side of another RS232 Communications and FDX System Interface card.

It is not the one in the photo above, it is the board that Martin Allcorn gave me in 2014, but it is identical.

Option ROM Board

This board was available with NewWord and/or Hi-Soft Pascal ROMs installed, this is a photo of my board with Pascal fitted.

Solder side of the ROM board
This is the combined 80 Column and RS232 card designed to mount inside the MTX and allow SDX disk systems to run CP/M. The 80 column functionality is the same as the FDX board and it has the same RGB and composite outputs.

This one is fully populated, but some boards only had the 80 Column functionality and were missing the Z80 DART and support chips.

This example is soldered to the MTX internal edge connector, making its removal somewhat problematic!

This is the 80 Column board from my other MTX512S2, thankfully, this one does not have its edge connector soldered to the MTX and it does not have the external 5V PSU connector installed.

This board does not have the  required ICs for the RS232 interfaces installed.

Solder Side of the 80 Column board
My MTX512 and FDX - bought from new.

As you can see, I have replaced the two original QumeTrak 142 5.25" drives (Memotech Type 03) with two 3.5" Sony MPF920 drives (configured as Memotech Type 07).

The original Astec AC8151 PSU has also been replaced with a HEC-200SR-AT, ATX PSU.

For photos of FDX examples, see my FDX photos page

SDX Controller - Original Version

This is my "old" style SDX Controller, bought from a seller on ebay Germany, although it would originally have come with a Memotech 5.25" floppy disk drive, I did not get the drive with it.

I have added a 3.5" disk drive to my controller, it takes up less space and 3.5" floppies seem to be more reliable than the 5.25" ones.

The rear of the SDX controller, showing the 34 way IDC connector for the floppy disk and the 5VDC input that would originally have been supplied by the PSU in the Memotech floppy drive through a cable connected to the 3.5mm jack socket.
The "FDC05" Floppy Disk Controller board fitted to the SDX.

The board has the SDX CP/M ROM fitted and can therefore drive the 80 Column board in the MTX shown above resulting in a fully fledged CP/M 2.2 system with a much smaller footprint than a comparable FDX system.

This board was designed by Tony Brewer, with Tony's help, I have drawn a schematic of this board - available on the Manuals page.

 

Solder side of the SDX FDC05 Disk Controller

 

Additional photos are available on the SDX Photos page

SDX Controller - Series 2 Version

The "new" style SDX controller with integral 3.5" drive. To incorporate the drive, the profile of this SDX is much "squarer" than the MTX and original SDX controller.
The base of the Series 2 SDX controller, there are two tapped holes adjacent to the edge connector for a metal plate used to attach the controller to the base of the MTX, intended to provide a more secure connection.
Top cover removed, showing the disk drive and interface cable to the disk controller board.

The drive fitted to this SDX is a NEC FD 1036A

Internal view of the SDX with the floppy drive removed, exposing the disk controller, and "FDC/SI Disc Issue 2" board.

This SDX has the optional CP/M ROM as well as the optional 512k of memory installed on the disk controller. The memory on the disc controller was available for use as a RAM disk

Additional photos are available on the SDX Photos page

DMX80 Printer

DMX80 Printer Controls

Paper controls on the left hand side

Control panel on the right hand side

DMX80 Printer - right hand side

Showing power switch and manual paper feed knob

DMX80 Printer - rear

Showing the model & serial number label, mains lead and Centronics connector.

DMX80 Printer - underside

The 8-bit switch pack at the rear of the base is used to configure the printer settings such as Print Mode (Pica or Elite) and International Character Set. The function of the individual switches is described on the Tech Tips page.

 

Multi-Effect Videowall Pictures - courtesy of Mike Rudkin

The MTX computer used for the Videowall System. You can just make out the Cameron Video Systems logo on the left hand side of the keyboard label, probably just stuck over the original Memotech one.

Most were MTX512 Series 2s, but I think some were also the RS128 model.

Photo of the MTX Videowall computer internals, showing the main board, a ROM card and a cut-down RS232 interface which lacks the interface components used for the FDX etc. The additional ROMs allowed the system to boot into the Videowall system without the need for the optional SDX disk drive.
The internals of the Videowall Controller. 

Each half of this controller has a Controller board and 4 or 5 Frame Memory boards, providing for 9 monitor outputs. The controller boards were multi-dropped on the ribbon cable connected to the MTX Centronics interface which is visible next to the silver UHF modulator in the photo above.

The frame buffer box looked very much like an FDX case, it was variously described as the "Black Magic box" or the (Distributed Digital Frame Store) DDFS control unit.

The Videowall controller also had a second, smaller, "Black Magic" box, this was a composite video decoder. Its function was to take the composite video signal and split the components into (R)ed, (G)reen, (B)lue and (S)ync - RGBS.

The lower board is the demodulator board, it accepted a composite video input and output RGBS to the Videowall controller. The large chip in the middle of the board is a ST Microelectronics PAL/NTSC One Chip Decoder, TDA3562A.

I have seen pictures of two different designs for the second control box, Peter Kretzschmar's Videowall has a simple video amplifier/splitter board installed with the demodulator board. Mike's board shown here has a much more complex second board which I assume performs the same basic function with some added complexity. Andy recalls that there was a module referred to as the "Multi Source Control Unit", this may be what is shown here.

 There are more detailed photos of Video wall systems Video wall Photos page

 

Miscellaneous Pictures

Earlier versions of the MTX computer board (Rev.04), like the photo of the MTX500 board shown above, had 2 ROM chips fitted.

Later versions (Rev.05 & 06) had 3 ROMs fitted, like this MTX512.

And this one
High Res Photos of the MTX 4000-05 Board

These are 5MP photos and are over 3MB in size

(Photos courtesy of Paul Daniels)

Photos of the MTX 4000-06 Board

The 4000-06 computer board is highlighted in the MTX500/512 Service Manual as a multi-layer board.

(Photos courtesy of Peter Kretzschmar)

Photo of the inside of another "imposter" MTX512 with only 32k RAM, also showing the underside of the keyboard PCB.

(Photo courtesy of John Halliwell)

An MTX512 with an SDX disk controller and 5 1/4" floppy disk drive attached. Looks like a pretty standard MTX computer ?

(Photos courtesy of Peter Kretzschmar)

NO! - It's one of the most heavily "modded" MTX512 that I've seen.

On the left: 1 MB SRAM - but only 768kb usable

In the middle: RyByY -> RGB Converter

On the right: 80 Column Board

Close up of the custom RAM board and the end plate.

Even the 80 column board has been modified with a switch to toggle between the TMS VDP and 80 Column Board output

But if you want to see something REALLY impressive - look at this page!

Photo of the "fabled" MTX in a red case!

This one is an imposter though, it is a standard MTX512 with one of the red keyboard covers fitted, rather than one of the demo machines built for the Russian bid.

(Photo courtesy of Jim Wills)

Another MTX512 in red - the only other example that I know of.

This one owned by Noel Long, like Jim's, this is a standard MTX with a red keyboard cover fitted, rather than one of the actual demo models.

Photo courtesy of Noel Long
RS128 - This one was advertised on ebay UK in 2013 (from Finland)

Probably the best photo of an RS128 on the web! (unless you know better?)

Photo courtesy of Aki Sivula

MTX512-S2 (Series 2)

The extra length on the left hand side is the optional SDX Disc unit with in-built 3.5" floppy disk drive.

You can just see the composite video connector from the optional 80 Column Board on the right hand end plate.

MTX512-S2 (Series 2)

(Photo courtesy of Peter Kretzschmar)

MTX512-S2 (Series 2)

Internal view showing the combined 80 Column and RS232 board with the RGB and Composite Video monitor connections on the end plate.

MTX512 Undeveloped Prototype 

This is an extended length MTX, some 3 1/2" longer than the standard MTX.

I don't think that the prototype ever made it into production.

Geoff Boyd commented "I believe this was a (very) limited run of MTX 512s with single drive Floppy disk Controller card and 80 Column card in the extended enclosure." 

Other than the standard MTX computer board, the machine shown has no additional internals fitted.

The machine has no serial number and the rear panel identification labels are missing - supporting the theory that this was a prototype model.

Information & photos from Binary Dinosaurs / Geoff Boyd.

An early version of the SDX Disc Option.

This controller supported up to two disk drives, a 5.25" drive is shown, but it was also possible to connect 3.5" drives to the same controller.

The SDX Controller attached to the edge connector on the left hand side of the MTX computer and a ribbon cable at the rear connected to one or two floppy disk drives. The Memotech SDX "Flyer" can be seen on the Articles page.

Peter Kretzschmar's 5.25" SDX controller

SDX Rev 5 Floppy Controller for a maximum of 2 Drives DS DD 80 Track and 5.25" disk drive

(Photo courtesy of Peter Kretzschmar)

A later version of the SDX had a 3.5" drive in the same case as the controller.

This also attached to the MTX edge connector and was fixed with a metal plate on the bottom of the case. I don't know if the earlier model had the bracket too.

The floppy controller could also hold 512KB of RAM which was made available as a Silicon Disk. You can also see the CP/M PROM installed on the board.

 

              

These pictures of Peter Kretzschmar's SDX controller with integral 3.5" floppy disk.

The Silicon Disk is not populated and the board looks like a very early version, you can see various wiring mods have been done the board, particularly around the 74LS244.

 

Photos courtesy of Peter Kretzschmar

More photos of different SDX models is on the SDX Photos page

Another sample of Peter's extensive collection

This time it is set of photos of what could be a variant of the Business/2.

Photos courtesy of Peter Kretzschmar

A half height, FDX style case and keyboard marked MTX500 with rear connections for Centronics printer port, serial port, modem, mono and colour monitors and keyboard.
The disk unit shows the Series 2 style logo while the keyboard shows the old style Memotech and MTX512 labels.

The 3.5" floppy disk drive is on the right of the disk unit.

The keyboard has no electronics installed, other than the keyboard matrix itself, the MTX system board is installed at the bottom of the floppy drive case.
The floppy disk drive is on the left hand side of this photo, in front the power supply. The floppy disk controller/RAM disk is in the upper centre, with a combined 80 Column and RS232 board on the right.

On the bottom right, in front of the main MTX board, is a modem card.

On the left, a close up of the Power Supply Unit, although it is an Astec PSU, it is a different model to the one fitted in the FDX.

On the right is a close up of the modem board built around a AM7910PC "World Chip " V21/V23 modem. The two square switches on the rear of the disk unit were probably used to set the mode of the modem. (The modem chip has 5 digital inputs used to select its operating mode from a range of Bell and CCITT standards which defined the baud rate, originate/answer mode etc.)

Close of the internals showing the edge of the 80 Column/RS232 board, with the edge of the MTX system board below it.

The last photo shows how Peter has matched a Commodore 1950 monitor to the black of the MTX - nice paint job!

An interesting photo of an MTX500 (it must have had at least a 32k RAM expansion board installed) and a twin 5.25" floppy drive FDX. This items was sold on ebay Germany in 2012.

The floppy drives are not the standard Qume type, they look to be Epson SD-521. The motor in the SD-521 is direct drive, rather than the belt driven Qume.

   
Another "RS232" & FDX Interface Board

This one was installed in an MTX512 sold on ebay.de in January 2013 at the same time as an FDX. It does not have a DART or supporting chips fitted, and the PAL is marked "I/F Only". 

This is not a "one-off", I know of at least one other board that has this configuration.

MTX512 Board with no Video hardware

The same MTX512 as above was sold with no Video Display Processor or PAL/NTSC video board fitted. It would obviously have been unable to drive the normal MTX video or TV outputs.

If the machine was shipped this way, then it looks like Memotech were really cutting costs to the bone by this point.

This is the single drive FDX listed at the same time as the MTX500 above.

This is a true FDX, single drive, model with an 80 Column board and supplying power to the MTX, rather than the "budget" single drive, non-CP/M version.

I would have expected the single drive to be on the left, on the twin floppy CP/M version, the drives are "B" and "C" - "A" is mapped to the boot drive.

Rear view of the FDX above, showing the power connections on the left, the monitor connections on the right and the expansion port cut outs in the middle. This FDX is unusual in that it has an actual IDC for external 8" drives, rather than a blank cover on the expansion connectors as most FDXs have.
A set of detailed photos of the inside and outside of different FDX models is on the FDX Photos page
   
DMX80 Printer

Photo courtesy of Peter Kretzschmar

Another DMX80

In slightly worse condition, missing the top cover, but showing the printer ribbon an carriage rails

Internationalisation

International character sets and appropriate keyboard layouts were available for UK, US, Finland, France, Germany, Spain, Denmark and Sweden. This appears to have utilised an additional ROM piggy backed onto the OS ROM and some custom wiring on the motherboard like this Danish example.

Photo courtesy of Claus Beakkel

A close up of the language ROM piggy backed onto the OSROM

Photo courtesy of Claus Beakkel

And the other side, showing the "yellow wire" connection to the system board

Photo courtesy of Claus Beakkel

Close up of the ROM with the "Danish" label removed.

The ROM part number, "N82S181N", can be clearly seen, an 8K-Bit TTL Bipolar PROM (1024 x 8)

 

Generic Photos

MTX500 from Wikipeda

Downloaded from Wikimedia Commons here.

Click the text to open a medium or large size image of the keyboard.

Another MTX500 photo with profile views.

Downloaded from Wikimedia Commons here.

MTX512 from mo5.com

A French language website dedicated to the preservation of computers and videogame machines.

MTX512 with German language keyboard
MTX500 with German language keyboard

(From ebay.de January 2013)

MTX500 On the cover of  "Your Computer," June 1983 

This was prior to the launch so I'm assuming that this was an early prototype. The keyboard layout is as per the production model, but the colours and Memotech logo are not and the MTX logo is missing. If you look closely, you can see what became the "BS" key is labelled in full on this keyboard, the Function Keys are numbered from "F0" to "F7" instead of "F1" to "F8"and the reset keys are identified, rather than having blank key tops as in the final version.

MTX500 From the Earls Courts Computer Fair

The Design is now the same as the original advertising brochure, the logos were changed again before the machine made it into production. (See the articles page for more.)

   
   
   
   

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