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The Memotech MTX Series


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Memofest 2017 was hosted by Martin Allcorn in Hastings on 14th October

As usual, I was unable to attend, but did manage to drop in briefly via Skype


As is traditional, the event featured a Memotech themed cake.

This year, the cake's "flavour" was Pot-Hole Pete. The cake was a very nice fruit cake baked by Martin's mum and iced by his sister.

I can vouch for the quality of the cake as Martin kindly sent me a sample after the event.

As I was not able to take much part in this year's event, I have gathered together some of the info and photos posted by Andy on his website and Mark's post on Memorum and posted them below.
Martin had a selection of his MTX related hardware on show
The monitor on the left is displaying the VGA output from CFX-II with the mono monitor displaying the normal MTX composite video output.

Martin's "MTX-mini" is shown in the foreground (see below)

(Photo courtesy of Mark Kinsey)
Close up of a CFX-II PCB - the main components include :

A 40 pin Parallax Propeller driving the VGA display output
An 8 pin serial EPROM containing the Propeller program code
A 32 pin CFX-II ROM
A Dallas DS1250Y NVRAM providing a 512k SiDisc
An Altera MAX7128 CPLD containing the glue logic
The CF card reader
(The empty socket is for a 32k SRAM for MTX500 RAM upgrades)

Caution : Blatant plug to follow . . . .

For details of CFX-II, including availability, see my webpage here

(Photo courtesy of Mark Kinsey)
Martin's REMEMOTECH was on show

REMEMOTECH is designed by Andy Key and is a complete MTX/FDX/SDX system implemented in VHDL on an Altera DE1 development board - shown to the right of the picture

(Photo courtesy of Mark Kinsey)
Martin's MTX Mini - hiding inside a custom MDF keyboard

(Photo courtesy of Mark Kinsey)
MTX Mini internals

(Photo courtesy of Mark Kinsey)
Description of MTX Mini (courtesy of Martin)

The home made box hides a component reduces sort of MTX like system, one of a couple of experiments I'd tried with the intention of making a replacement Main board using more modern components.

Under the cover is a Z80 running at 9.8304 Mhz (the odd speed is a consequence of the requirements of the serial connection), memory, CTC, SIO and serial to USB adaptor, plus the various support chips.

On the other side of the connector is a propeller video display from the CFX built onto a MTXplus+ compatible connector. In theory it could run MTX basic, however it would need the display handler re-written. With only the 80 column display it's really intended to run CPM. Which it will, using the same disc images as the CFX and CFX-II, booted from a modified CPM rom.

Over all though it's still too big to fit the mounting rails under the keyboard in a real MTX. More work needed!
Martin's set of MTXPlus+ PCBs was also on display

If you look closely, you might just make out the board designer's name on the backplane PCB  

(Photo courtesy of Mark Kinsey)
We had demo'ed MTXPlus+ at Memofest 2016 and until then, I believed that it would be 100% software compatible with the MTX.

However, we found that Andy's HEX-TRAIN game would not run due to differences between the MTX TMS V9929 and the supposedly compatible Yamaha V9958 used in MTXPlus+
Subsequently, Andy did some investigation of the incompatibilities and was able to demo a version of HEX-TRAIN for MTXPlus+ at this year's Memofest - thanks Andy !

You can read Andy's description of how he managed to get HEX-TRAIN working on MTXPlus+ on his website here.

(Photo courtesy of Mark Kinsey)
Jim brought along his Memotalk, a speech synthesizer for the MTX

(Photo from Memofest 2013, courtesy of Andy Key)
Martin removed the Memotalk PCB from the case

As shown in the photo, the device used a GI SP0256-AL2 digital speech generator

(Photo courtesy of Martin Allcorn)
Solder side of the Memotalk PCB

(Photo courtesy of Martin Allcorn)
Apparently somewhat confused as to what Memofest was all about    

Jon Bradbury took along some random hardware . . . .   

Although, both systems being capable of running CP/M, I believe(from Andy's report, that they did generate some interesting discussions

A Tandy/Radio Shack TRS-80 Model II . . . .

(Photo courtesy of Andy Key)
And an Amstrad (PCW?)

(Photo courtesy of Andy Key)
Z80 Coding Challenge
Although he did not attend the event, Tony Brewer had kicked off a Z80 coding challenge to be judged at the event. See this Memorum page for details.

Although there were a number of entries, nobody was able to beat Tony's model answer, so no winner was declared.
New Game
Paul Daniels showed off his new game.

From afar (Singapore) it looked like a PacMan variant, but Martin has advised that it's a combination of driving game and PacMan. The player drives in one direction, the CPU in the other. The player has to collect the dots avoiding a head-on crash with the CPU car.
Andy bagged the high score prize

(Photo courtesy of Andy Key)
Andy's Corner
As usual, Andy had something clever to show, this time, it was his additions to the SDX boot ROM that included a "Remote Control" feature, allowing data to be loaded to the MTX over the RS232 port.

See Andy's page for more details

(Photo courtesy of Andy Key)
There was some discussion of GUI front ends for MEMU

Bill demonstrated his "Launcher" - a Python script that takes the hard work out of using MEMU's many command line parameters.

Launcher is available here

I really like Launcher - particularly as Bill included quite a few "nice-to-haves" at my request - thanks Bill !
The webpage also includes a Gamebase installation, built by Paul for MEMU.

As described on Andy's page, "we spent a little time trying to set up Gamebase to run MEMU. If MEMU displays an error and terminates, it writes a message to stderr, but this does not result in a pop-up error window in Gamebase, making it a bit tricky to diagnose problems."
Memotech Hospital
Paul's MTX

The first patient on the table was Paul's MTX which had an intermitten video fault. Due to luggage limitations, Paul only brought the suspect Video daughter board along to Memofest 2016, but the daughter board proved to be working fine.

This year, will the complete MTX available, the prospective surgeons (Mark and Andy) were unable to reproduce the fault, so no progress was made on the day. However, the following day, Martin noticed that it "looked like one of the capacitors on the Video Daughterboard could possibly be shorting to a via on motherboard. One small piece of insulating tape later the potential short was history. An hour long soak test and still no problems so hopefully that's one system fixed at least for now. "
Jim's sexy red MTX

Jim's pseudo Russian MTX was next up on Sunday morning, it had a number of issues which Martin was able to resolve as he describes below :
The 2nd repair booked for Sunday Morning was Jim with his red MTX, which had no display.

We connecter it up to the monitor, and as expected the display was blank. However in order to know whether we had a black screen which is a common fault, or a blue one we connected the old TV. Which produced a flashing cursor and "Seady" and a few random exclamation marks on an otherwise working display. We swapped the daughter board and then on the next re-boot had the same display on both screens.

An close examination of Jim's daughter board provided the answer. The was no link in either of the 2 jumpers that allow colour or mono composite output. Fitting one link solved the missing display problem.

I plugged in the CFX-II board so that the start-up screen would give us a display to help diagnose the corruption of "Ready" into "Seady" and it was obvious that the lowest bit of the display ram wasn't outputting correctly.
 The Circuit diagram suggested this should be the chip in location G4 which we confirmed with a 10R resistor grounding Pin 14.

That chip came out and was replaces with a socket and one of the re-cycled 4116 chips from the spares box. Video corruption solved.
Next up was fitting the Magrom internally and a "test" of some of the games. That revealed a 3rd problem, the "H" key didn't work. Changing the cable didn't change anything so we connected my keyboard, that worked as expected, confirming the motherboard was fine and that the issue was the keyboard itself.
 Experimentation confirmed it wasn't just the "H" key, but also "F" Cursor right and a few others. All keys connected to the same pin on the keyboard connector.

Tracing with the meter confirmed a break in between the connector and the first of the keys connected to it. Being a Memotech, that required a yellow wire to restore connection.
With (hopefully) everything now fixed we were able to test the Magrom and confirm for now at least the Ultra Rare RED MTX WoW!! is working.

And Jim was finally able to head for home with his repaired MTX and a large chunk of the Pothole Pete themed cake as souvenirs of his trip to the South Coast.




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