The Softy project.

Softy is the translation of the abuse of a partname. The project is based on the Zilog Z8681 microcomputer. It is based on the Z8 core.
If you pronounce 'Z8' in dutch, you get 'Zacht' which means the same as 'Soft' in english. So now you know why the project is called Softy.

Softy is meant to be used on Linux systems. If you set out to use a multi-user multi tasking operating system, in which security and reliability are the bottom line, you also must face the consequences: no more tinkering on the LPT port.
OK, it CAN be done, with IOPERM functions and such, but that kind of program is a security breach and should be avoided. My rule is simple: if you want to use a modern OS, use Linux. If you want to fool around with home made gadgets on the printerport, use DOS.

Softy will use a 12 MHz Z8681 ROMless microcontroller with 4 Kb or data memory, 2 Kb of bytewide EEPROM for booting and 2 Kb of SRAM for additional code memory.
It will also have an I2C serial EEPROM of 32 Kb on board for storing program code that is not used every day. This code will be loaded into the 2 Kb SRAM in code memory space.
Softy will communicate with the host PC via COMlink at 9600 bps. You connect your LPTport gadget to Softy, give it some additional code and let it run standalone. All communication is done via the COM port, running a terminal program under your favorite operating system.

As of this moment, I am wiring up Softy (I use wirewrap).

The circuit as I'm building it now.

Softy circuit, version 2003
This PNG file was created by converting a HPGL plotterfile with 'hp2xx' on my Linux system.

Some pictures of Softy so far.

As you can see, you must also be kind of a carpenter to be a wire wrapper. :o)
Luckily not much wood is involved.

The wooden container serves multiple purposes: it protects the long pins from bending (and making short circuits), it protects the CB for making short circuits when places on a table top and it makes the project heavier, so it wont fall off the table so easy.

What you see here (to the right) is the topside of the CB (Circuit Board) in it's container with the wire wrap tool and a bag of prestripped wrapping wires on top of it.

Wire wrap is a somewhat expensive technique, but I chose it 20 odd years ago, so now I must choose between throwing away lots of wires and sockets or keep the technique and occasionally stock up on sockets. I'm still using my original assortment of lengths/colours....

To the left, you see a close-up shot of the wire wrapped connections. The technique is just what it says: wires (AWG 30) are WRAPPED around special posts. The posts are 32 mil square posts with sharp edges. This ensures a good mechanical and electrical connection.

Wire wrap is a good, fast and flexible system. It can be done completely cold, but when connecting resistors and capacitors, it can be handy to solder these directly to the respective pins.
As you can see, I also apply a little bit of solder to the lower left and topright pins (the power pins of IC sockets). This makes wrapping easier and it keeps the sockets in place.

And another shot, now with the wire wrapping in a much further state. It's close to finished now. All busses (power, data and address) have been routed. Now it's finishing up time again.

Here you see a picture of the unpopulated topside of the circuit board. Not much difference with the other picture in the top of this page.

This is it, lads. I found out I was the only soul in the world who still had some stock of this kind of processor. So even if I could have made the project, nobody else would have eben able to copy it. I will revert to the Atmel AT Mega 16.


The Z8 is one of those epic processors that sem to draw attention of many newcomers. And they have a large base of engineers that ever used it. Many of them come across this website. Some of them report in for more information or to share some information. This section deals with it, to show the popularity of the chip and to enable Z8 enthusiasts to visit each others sites.

Page created April 2003,

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