2. Arduino hook up.

Last Christmas, I got my wife to buy me an Arduino UNO. I'd had a passing interest in electronics from an early age when my father gave me his Denshi Block electronics set to play with. I just had to open the book of projects and place the components exactly as in the picture, connect up the battery and annoy my mother playing the electronic cat sound all day. So I knew from an early age, what the components were, but not necessarily what they did. This probably lead to me blowing up my ZX Spectrum by adding a reset switch and kind of put me off wiring up anything else and breaking it and instead I entered the world of software.

For £20, the Arduino has all the electronics, all I need to do is program it on the PC to turn a pin on and light up an LED and my interest in electronics is rekindled. If I break it, well I could fork out another £20.

I had a brief play with the UNO at Christmas but don't get much time to play with it until about 8 months later i.e. now. Having tamed the electronic beast and even got it to drive a 16x2 LCD display from Maplin, I start to look for a project. So I buy the Z80 CPU. Fortunately it was the better choice for a project as it can be easily hand cranked, compared to other processors of the same era e.g. the MOS 6502.

All CPUs need a pulse to come alive. Pin 6 on the Z80 the Clock Input and this expects to see a voltage go low then high, then low then high etc. Each time the voltage goes low, the processor moves on a step. For the Z80 it takes at least 4 clock tics to process an instruction. Ultimately the Z80 should be able to jog along at 1 million tics per second or 1 MegaHertz (MHz). I want to understand how the Z80 ticks (no pun intended) and to do this I want to see changes happen visibly (such as an LED going on and off) so I want to control the frequency of the tics.

I begin to wire up the Z80 to the Arduino...