MC14500

2 Articles

What Everyone Else Did With Eight Bits, The Germans Did With Only One

February 1, 2020 by 50 Comments

In the 1980s there was an impetus for the first time for young people to be equipped with computer literacy. A variety of different educational programmes were launched, typically involving a collaboration between a computer manufacturer and a broadcaster, and featuring BASIC programming on one of the 8-bit home computers of the day. One such educational scheme was a bit different though, the German broadcaster WDR produced an educational series using a modular computer featuring an unusual 1-bit processor that was programmed in hexadecimal machine code. [Jens Christian Restemeier] has produced a replica of this machine, that is as close to the original as he can make it. (Video, in German, embedded below.)

The computer is called the WDR-1, and had its origin in a kit machine before it was taken up by the broadcaster. The unusual 1-bit processor is a Motorola MC14500, which was produced from 1977 onwards for industrial control applications. He takes the viewer in the video below the break through the machine’s parts, explaining the purpose of each daughter card and the motherboard. Lacking an original to copy he instead worked from photographs to replicate the chip placements of the original, substituting pin headers for the unusual sockets used on the 1980s machines. Take a look at his video, below the break.

More information on the WDR-1 can be found online in German (Google translate link). Meanwhile we’ve featured the MC14500 before, in a small embedded computer.

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Building An Industrial Control Unit With An Industrial Control Unit

February 26, 2015 by 28 Comments

Back in the 70s, industrial control was done with either relays and ladder logic or new programmable logic controllers. These devices turned switches on and off, moved stuff around a factory, and kept the entire operation running smoothly. In the late 70s, Motorola came out with an Industrial Control Unit stuffed into a tiny chip. The chip – the MC14500 – fascinated [Nicola]. He finally got around to building an ICU out of this chip, and although this was the standard way of doing things 30 years ago, it’s still an interesting build.

[Nicola]’s ICU is extremely simple, just eight relays, eight inputs, the MC14500, a clock, and some ROM. After wiring up the circuit, [Nicola] wrote a compiler, although this chip is so simple manually writing opcodes to a ROM wouldn’t be out of the question.

To demonstrate his ICU, [Nicola] connected up an on/off switch, a start button, and a stop button. The outputs are a yellow, green, and red lamp. It’s a simple task for even a relay-based control scheme, but [Nicola]’s board does everything without a hitch.

If you’re looking for something a little more complex, we saw the MC14500 being used as an almost-CPU last year.

Video below.

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