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.

The Wichit Sirichote Z80 MICROPROCESSOR KIT.

Building the kit :

12/05/2020 Update : development of a new  fully compatible and easier to use version, based on FPGA, here : https://sillycony.blogspot.com/

I bought recently this kit from the eBay store of Wichit Sirichote (http://www.ebay.fr/sch/kswichit/).

I 'talked' here about the serie of different kind of kit that Wichit currently sells, based of several vintage processors. 
The built kit 'must' look like this : 

From the Wichit blog.

So, after a little delay, I received a nice package from Thailand : 

 

Thanks Wichit.

The kit contains all the necessary parts to build the système, of course :

Parts

PCB

List

I juste have to report that only the R7 resistor were missing, a 680 Ohms. A common value that my personnal stock provided... The PCB is of professionnal quality with some 'funny' weird things like holes (for the LCD display) under ICs : not matter!

To populate the PCB I did't need the construction manual because all is very simple and well identified onto the PCB and the part list (even the direction of the TVS diode), exept the resistor placed between the Z80 and U4 which is a 10K Ohms.

I began to place the little componants and specially those that provide the 5V. A rapid voltage test confirmed the présence of the power on all the ICs footprints.

Done!

I continued with the ICs with/without their sockets. I placed only the RAM/ROM/PLD/AT89 and MAX232 on sockets. The others ICs were directly mounted to the PCB, like the processor. Then, I placed all the others components.

The Z80 provided with the kit was a Toshiba version. I have nothing against Toshiba, but, for a vintage Z80 computer, I prefered to place an original Zilog Z80. The one used has a date code of April 1983 : perfect.

And the very first power test : 

Without the red filter.

Better with the red filter.

Some thermal pictures of the device in operation : 

One other component heats up a little, it's the GAL, but just around 30 °C.

It should be noted that the temperature of the regulator, in this case, is generated by a power supply of 12V and not 9V as recommended. It should be significantly lower with a 9V power supply.

Conclusion : I bought this kit 'to be built '. It took me juste a couple of hours to do that.
I did not encounter any problems and it worked as soon as power was plugged in.

The keyboard is not the 'better possible' with the plastic printed layer in place but still very usable.

Now, I have to do some programs for it and, of course, make usefull extensions with the extension port!

A very good kit for the price, even better if you buy it not builded!

07/04/2017 update : I made some improvements and modifications to get this board easier to play with.


First, I replaced the MAX232 converter IC with a USB to serial bus micro-module converter. The solution is not intended to stay in place but just when the board is in the 'developpement mode'.

To get this solution very fine, and not to have to plug this module and load the programm every time I power up the CPU80 board, I also replaced the static RAM with a non-volatile one. 

Very usefull!

11/29/2017 update : upgrade the kit to the popular uPF1 version with new PAL and EPROM, burned with a Minipro TL866A  (in french).