mardi 30 mars 2021


You know what? This morning the postman had a little surprise from Canada for me:

A new type of processor board specially developed for retro-computing, based on the WDC65C816S @ 14MHz processor and with at least 2MBytes of system RAM. Interesting isn't it?

It only remains to learn how to use it to develop interesting applications. Admit that this type of system is still more 'fun' than the endless and practically all identical boards on which the same Linux has been running for over 20 years!

lundi 22 mars 2021

uPF--2 : Beginning of electronic board design.

After having worked on several personal electronic boards as well as on the reissue of microcomputers, I can finally start designing my personal FPGA board.

This is a minimal system intended to replace the Z80 µPF--1 compatible development kit that I have mentioned several times on this blog.

The diagram looks something like this:

Overall this board is not very complicated and pretty much picks up the basic elements of the original design. I just added a few useful components that were lacking on the base board. 

I also modified the extension connector to present only a few interesting signals and not all of the data and address buses. I prefer to use expansion boards already created for other systems rather than recreating specific expansions.

It remains now to perform the most difficult part, the routing of the board:

It's not what I like most to achieve ;-)

mercredi 17 mars 2021


As I mentioned in my previous post, this computer is not very difficult to assemble for those who have decent experience in this type of work. In fact, the hardest part is getting all the components. At one point, we still come to the end of this quest:

The 'only' component that is missing is the battery. But Cbios (MSX compatible) can do without it. The first start using a laboratory power supply with controlled intensity allowed me to avoid the 'magic smoke'!

And voilà :

The message is clear, the system is now waiting for an application cartridge. Note that I did not mount the keyboard proposed by the designer of this system. Standard USB keyboards are much less expensive. I intend instead to develop an interface allowing the use of a commercial keyboard on this computer.

There is therefore still a little work to be done to be able to use this MSX computer in a comfortable way, but the basic system is operational. This is a very good start. Well done to the designer of this Omega!

mardi 9 mars 2021


With Covid, it's not very easy to move forward with the projects I'm working on right now. For example, I am mounting an MSX type computer board. This is Sergey Kiselev's Omega project available on Github at this address: The computer looks like this when mounted:

This computer is built from standard 'old' components but still relatively easily available. On the other hand, this implies the use of a multitude of sources of supply because it is totally impossible to find all the components from one supplier. Not that it's complicated, but it really takes a lot of time and organization. We also have to face long delivery times due to the Covid. The assembly of the board is not of great complexity but requires patience and a good practice of the soldering iron. It is definitely not a beginner's job.

My first board is almost finished: 

In fact, I have ordered components for several boards. No need to generate all these global transports for a single copy. I may offer a few mounted boards for sale. I plan to use this first one as a prototype for some future developments, because the MSX standard is still active and dynamic.

The Z80 which equips this type of equipment is definitely an excellent processor for familiarizing yourself with the architecture of computers and their programming. This is obviously a totally different approach to the 'virtual' world that is programming under Windows for example. I think that creating an application for such a machine is much more rewarding than running your first (boring) 'Hello World' application in its 'little window' ;-)

Other projects will soon be completed. I'll post on this blog when it's done ....

mercredi 20 janvier 2021

PLC PACK for the Colour Maximite 2

After working for a while on the development of the vintage PAL reader for the Color Maximite II micro-computer, I went on to test the PLC type expansion board.

This expansion is equipped with
  • - 3 opto-isolated logic inputs.
  • - 3 relay outputs
  • - 2 analog inputs 10V
  • - 1 DS18B20 input
  • - 1 TTL serial communication port
  • - 1 RS485 serial communication port (optional)
The tests are almost finished :

In this picture, I have connected two control/command screens of different type.

I connected a Nextion screen whose communication takes place by TTL serial link and thanks to a very simple exchange protocol in the form of ASCII frames.

I also connected a second screen which is used in PLC systems and which communicates in Modbus ASCII through an RS485 link. This screen is used to test the control of the outputs of the PLC board.

The program in Basic uses an interrupt to manage the system timer, another interrupt to manage the triggering by the logic inputs of the board and finally a last IRQ for communication with the industrial screen.

Everything works smoothly and very responsively.

I am very impressed by the efficiency of this system, as well as by the basic interpreter which allows to manage without problem all these different interfaces.

The original Colour Maximite 2, an ARM7 based micro-computer :

Soon a more detailed description on

samedi 9 janvier 2021

Vintage PAL reader.

How to find the equations of old PALs that we find in vintage machines?

With this PAL / GAL reader:

More info here.

mardi 8 décembre 2020

A Drumulator in a FPGA?

After getting back to working with FPGAs for a few weeks, I took a first study of the Drumulator processor core to implement it in a Terasic DE2-70 board:

Obviously, shown like this, it is neither very sexy nor impressive. But, thanks to the keyboard with serial link previously made, I was finally able to observe for the first time the operation of the heart of the machine. 

More informations here :