PAL READER for the Colour Maximite 2

In the past, I have had to troubleshoot some Drumulator and more recently SP12. During this process it is necessary to understand the logical functioning of the machines. The problem is that among all the logic circuits, there is the presence of old PALs. These pals must be read to determine their logical equations. Unfortunately, there is no cheap pal reader to do this.

MiniPro TL866

Usually, a component programmer/reader like the MiniPro is sufficient to perform the read operation. However, this Minipro cannot read old PALs. The simplest solution is therefore to wire a breadboard connected to an Arduino like the Arduino Mega to perform the operation. 

Arduino Mega.

This is what I did to retrieve the PAL informations from the Drumulators. To do well, it would have been necessary to create a printed circuit board allowing an easy re-use of this system. However, I don't find the Arduino system to be particularly relevant for this type of application, especially for reading / writing files.

As I have just made a Color Maximite 2 computer, and this system includes all the elements to operate in total autonomy, I decided to create a PAL reading interface for this system : 

This board is really very simple. Once completed, it will remain to write the reading procedure program in Basic. What inspired me to use this computer is that with a processor which operates at more than 400MHz, the execution of programs written in Basic is really very fast.

In addition, adapting a program written in basic is very fast. On this system which has an integrated editor, a USB keyboard input and a VGA output, this operation is done without using a PC equipped with a compiler and programming software. It is really much more convenient.

As far as I'm concerned, I made the version of Maximite 2 presented on the picture above. This version is not very 'practical' to make because it requires a processor module available from Waveshare. Other sites offer a version where the processor is soldered directly to the motherboard. I also decided to do by myself some printed circuits board made of this version because it seems that, due to a strong demand for this Color Maximite 2, there are no more available on the 'market'.

Colour Maximite 2 Main board version without the Waveshare module.

You can find more information about the Color Maximite 2 on this site: https://geoffg.net/CMM2

EPS16+ update.

About two years ago, I was able to acquire a basic EPS16 + for around $150 in perfect condition. However, as it stands, the EPS16 + is not very interesting to use. 

The system and instruments are loaded using the floppy disk drive which, apart from being a slow loading system, tends to degrade over time and then break down.

The machine comes with 1MBytes of memory, which is not very important since it allows just 11s of sound at the maximum sampling rate. A little limited for the simultaneous loading of several instruments.

http://www.vintagesynth.com/

The idea, after having acquired this EPS16 +, was to try to upgrade it. However, the ensoniq company has not existed for a long time. So, how to find the necessary expansions, knowing that it is very difficult to find now.

Fortunately, there are people (like me ;-) ) who make such expansions.

Regarding the 'external' of 1MBytes and the SCSI interface, I turned to ZiN Circuits :

These boards are very easy to install and although I have not yet tested the SCSI part, the 1MByte memory is instantly recognized. 

This allowed me to test the multi-timbral capabilities of the machine under good conditions. On this occasion, it was easy for me to realize that loading several instruments using the original floppy disk drive was not a very reliable solution. I have had several reading problems and it took me a long time to do this successfully. 

So, time to switch to the HxC floppy drive emulator :

Once this floppy drive emulator was installed it was much easier not only to load the instruments but also to save my work. In addition, the system was loaded now without any reading problem.

But, all these operations were always done in a slow way since starting from, and towards what remains a floppy drive. 

There was an interesting expansion for the EPS16 + which consisted of a Flash Bank. In fact, a set of non-volatile flash chips providing a total of 1MBytes of storage for the system as well as a few 'favorite' instruments. 

The very big advantage of this Flash Bank is that the loading of the system becomes automatic after switching on the EPS. The loading of the instruments which are saved there is done this time instantly. In short: a must have!

I contacted Tom Virostek from http://www.straylightengineering.com/ which offers this board:

http://www.straylightengineering.com/

I installed this expansionvery recently, in fact, I have some photos taken during the operations.

First, the board must be mounted on the display board. The front panel already has the 'holes' which will receive the mounting elements of the board.

The expansion board holes are a bit too small (3mm it seems to me) and need to be enlarged to 4mm. Once this modification has been made, the installation of the board and the ribbon cable is carried out without problem. You can download the assembly guide directly from Tom's website : Ensoniq-Flashbank-FB-1-FB-2-Install.pdf

The red board under the Flash Bank ribbon cable is the SCSI board. Under this red board, there is therefore the 1MByte memory expansion board. Both of these were installed previously, as noted above. 

Once all the boards are installed inside the EPS, it looks like this :

Some pictures of the display taken after installation :

- 1- Formatting the Flash Bank.

- 2 - Insert the OS disk. In fact, choose the system file from the floppy drive emulator.

- 3 - Transfert the OS to internal RAM.

- 4 - After this opération, the system is copied from RAM to the Flash Bank and it's done.

Once these four operations have been carried out, the System is written in Flash. When the EPS is powered on, and having taken care to have removed any system disk first, the EPS will automatically search if it finds its system in Flash and, as is the case now, loads it directly from the Flash.

Therefore, the loading of the system is almost immediate. It really changes the life and the way to use this EPS16 +. 

Loading and saving instruments with this flash is also very fast. The only constraint is that once the system is written on it, there is approximately 1.5MBytes available. It's not huge, but it allows you to save the few favorite instruments of the moment.

You can download the user manual for this Flash Bank from the TOM website: EPS-16-Flashbank-Manual.pdf.

An absolutely essential feature to install in this machine!

3 output PSU.

Sometimes it happens that the power supplies of some machines need to be replaced. And sometimes I can't find the ones that suit my needs in stores or on specialized sites. So I developed my personal version.

I added some extra features that are not usually found and that can be very useful. Troubleshooting a few Drumulators and other SP12s proved this to me. 

It had been a long time since I decided to create this type of PSU. But between the initial idea and the realization of the concept, it can sometimes pass some time.

This PSU should be able to deliver 2A on each output. This is what I will have to check when the prototype will be made :

The uPF--2.

The Wichit Sirichote Z80 MICROPROCESSOR KIT clone : The uPF--2.

I worked on replacing the Wichit kit with an FPGA version. During this work, I said to myself that the keyboard had to be replaced. On one hand because I think that it is impossible to work under good conditions with the original micro-switches, and on the other hand, the multiplexing has not been correctly implemented and can present big problems in the event of simultaneous pressing of several keys. No protection diode and no phantom key suppression as been placed : 

The Wichit Sirichote original design.

Furthermore, I decided to recreate the keyboard as a separate part. This will allow me to develop the processor board independently. However, I also decided not to use a parallel link because it is not practical at all. I preferred to connect the keyboard with a simple serial cable to the processor board.

There are not many solutions for the choice of keys if you want something 'pro'. So I chose the Cherry type keys. For now, I have only studied the keyboard circuit. Here's what it should look like :

To be continued...

The Wichit Sirichote Z80 MICROPROCESSOR KIT (uPF--1 become uPF--2).

The original Z80 kit from Wichit Sirichote :

 

This kit is a very good equipment for learning the principles of digital electronics. But, in the uPF--1 version, I had some issues with downloading files using a PC. After studying the code of the monitor, I realized that the method used for sending and receiving through the serial port is not really appropriate.
In addition, the maximum speed of 2400 baud is really too slow for transferring even small files between the kit and the PC. 

So I wondered if it might not be interesting to study a new version of this kit, more robust and more flexible. And why not, faster too if possible.

So I started to investigate the possibility of transferring all of this kit into an FPGA circuit. The study was not easy at first, because I had to understand  the code of the monitor with precision to determine the general operation of this small computer. But, it is done now : 

The monitor work on the FPGA board.

Closer with a filter on the display of the FPGA board.

Next? the most difficult : implementing a real serial converter for transmission / reception with the PC, and adapting the monitor to this new component. 

[08-24-2020] The new version of SDCC, the V4.0.0, has been successfully tested on the FPGA board. For the occasion I renamed this version "uPF - 2" because it will be necessary to write new parts of code to manage the hardware extensions of this FPGA version.

Home Automation

En période estivale, forcément, le rythme des publications à tendance à baisser. Pour autant, en ce qui concerne ce blog, ce n'est pas vraiment la raison principale de cette légère baisse d'activité.

Non. C'est plutôt que j'expérimente une solution de contrôle et d'automatisation de bâtiments. L'idée est bien évidemment de vérifier un tant soit peu ce qui se passe à l'intérieur des locaux comme l'évolution des températures et autres valeurs de ce type, mais aussi d'en commander le fonctionnement comme le démarrage ou l'arrêt de certains systèmes ou la modification de consignes de fonctionnement.

Tout ceci n'est qu'un petit exemple des possibilités qui s'avèrent pléthoriques et de plus en plus utiles en cette période de mobilité réduite.

L'idée consiste donc à trouver des matériels fiables et des systèmes de mise à disposition des informations sur page web, comme ceci par exemple : 

 

Dans l'exemple ci-dessus, j'ai trois PLCs différents, dont celui affiché en image réalisé par moi-même, qui envoient trois mesures différentes de température. l'objectif étant de vérifier le bon fonctionnement de ces systèmes, seule la température affichée par mon PLC est pertinante. Les autres valeurs ne sont la que pour validation de la chaîne de fonctionnement des autres PLCs utilisés. En fait c'est le seul appareil permettant de connecter facilement un capteur de température 1-WIRE. Pour les autres graphiques, le premier provient d'une sonde analogique faite pour mesurer des basses températures n’excédant pas 24° et le deuxième provient d'une valeur fixée par programme donc par définition stable.

Différents protocoles sont utilisés mais l'action sur le switch (bouton du bas) se fait par abonnement à un broker MQTT. 

Tout cela fonctionne parfaitement. J'en suis à tester la 'reprogrammabilité' des PLCs directement par réseau afin d'obtenir un maximum de flexibilité. 

Sujet passionnant et fort utile. Le plus difficile, en fait, consiste à faire en sorte que tout ce fonctionnement n'émane pas d'une 'usine à gaz' propre à planter au moindre petit grain de sable! 

Dans les semaines à venir, je vais aussi tester quelques autres capteurs d'ambiance et d'énergie et puis progresser dans l'établissement d'une passerelle sans fil plus destinée par exemple à l'agriculture afin de surveiller les paramètres climatiques. L'utilisation d'un système sans fil fiable n'est pas, la-aussi, aussi trivial que l'on pourrait le penser. Les solutions toutes faites ne sont pas obligatoirement adaptées à ce type d'utilisation. Bref, encore un vaste champ d'investigation mais ayant pratiqué divers protocoles et diverses fréquences de fonctionnement depuis bien des années, je pense avoir aujourd'hui trouvé une solution satisfaisante...

Ce sujet semble assez éloigné de mes sujet habituels que sont les synthés, l'audio ou le rétro-computing, mais bon dans la description de ce blog, il y a aussi: "etc..." ;-)

Colour Maximite 2

Après avoir passé une commande pour le module processeur à base de STM32H7 chez Waveshare ainsi qu'une autre commande pour le circuit imprimé directement chez l'éditeur de la revue australienne Silicon Chip, j'ai reçu ces deux éléments de base quelques jours plus tard : 

Il n'y a plus maintenant qu'à se procurer l'ensemble des autres composants à placer sur le circuit imprimé principal pour être en mesure de démarrer la construction de cet ordinateur fort prometteur.

Parce que, comme il est indiqué sur la couverture du magazine ci-dessus, il s'agit d'un ordinateur que l'on peut monter soi-même, certes, mais surtout que l'on peut programmer soi-même. Même s'il s'agit du langage Basic qui est utilisé ici, la puissance de ce langage adapté à ce type de matériel (j'en sais quelque chose, j'ai eu l'occasion de tester les versions précédentes sur des processeurs pourtant moins rapide) offre un potentiel d'expériences incroyables, notamment dans l'univers de l'embarqué.

Avec ce type de matériel, nous sommes loin de la culture de l'ignorance perpétuelle telle qu'imposée depuis des décennies par microsoft (à son unique bénéfice), mais bien d'un matériel en mesure de servir le potentiel créatif de tout un chacun. Au jeune qui souhaiterait se lancer dans l'aventure, qu'il ignore les programmes archaïques et propagandistes de l'Education Nationale, et qu'il commence donc par quelque chose d'un peu plus sérieux et utile que ça :

Exemple de robot et de son langage de (non) programmation associé que l'on retrouve aujourd'hui dans les programmes de l'Education Nationale.

Au début des années 80, il existait le langage Logo, utilisable sur une base matérielle présentée sous la forme d'une tortue :

J'ai du mal à imaginer les générations de programmeurs de talent qui ont fait de la france la première puissance informatique mondiale. Bien au contraire, mis à part quelques ingénieurs de haute volée officiant dans des domaines extrêmement pointus tel que l'avionique, le pays est  devenue une colonie numérique, occupée par les puissances étrangères jusqu'à aujourd'hui majoritairement américaines, très prochainement Chinoises! 

Heureusement, en ce qui me concerne j'ai débuté en assembleur sur Z80 puis en basic sur ZX81. Cela n'inscrit pas du tout dans l'esprit le même rapport à la machine. Cela ne m'a pas réussi professionnellement, mais au moins cela me permet d'appréhender le monde technologique qui m'entoure ainsi que la propagande désastreuse et bien évidemment mensongère dont en font les politiques intellectuellement corrompus!