A TMS1122 Timer clone in a box.

The glorious era of the 80s

This venerable clock was programmable and allowed, thanks to 20 program steps, to control four outputs with an accuracy of one minute, over a week : gorgeous!

Personally, I have always appreciated the way this type of equipment works. An interface with buttons and a simple and clear display. A few minutes to understand how it works and voila!

So I recreated this type of clock but added some features including being able to program the start or stop of an output to the nearest second. This was woefully lacking on the original device.

Delay or advance can also be easily adjusted, which was not the case with the original machine. Here, there is no specialized circuit for time management. As originally, it is the processor that counts in real time. On the other hand, the precision is not based on the electrical main network pulsation but on the triggering of processor interrupts. As it is not clocked by a quartz, it is therefore relatively sensitive to temperature. In this way, the operation is identical to that of the TMS1122.

Some images of my new version of 'TMS 1122' :

The 16650 type accumulator allows operation with the display for approximately three days. Which is more than enough to compensate for possible power cuts. This time can be extended by putting the clock in 'ext' mode where less information is displayed, which increases the life of the accumulator.

CONCLUSION:

I must admit that the way the TMS1122 works was not at all easy to emulate. What was undoubtedly very 'easy' to achieve in assembler, is less simple in structured language like the 'C' used here. The functioning of the TMS1122 was certainly dictated by the obligation to work in assembler, with limited resources. Emulating the apparent simplicity of how the interface works was no small feat, far from it!

Offering a professional finish and easy to install product, is not easy either. But it's done. As presented, this programmable clock can be installed in a box and correctly manage its four outputs.

I plan to extend the capabilities of this timer in later versions which will improve the features already present and which will possibly offer others.

Stay tuned...