I'm a bit of a beginner at circuit design, and wanted to tinker around with creating a circuit that uses a [z80](http://www.zilog.com/appnotes_download.php?FromPage=DirectLink&dn=PS0178&ft=Product%20Specification%20(Data%20Sheet)%20%20&f=YUhSMGNEb3ZMM2QzZHk1NmFXeHZaeTVqYjIwdlpHOWpjeTk2T0RBdmNITXdNVGM0TG5Ca1pnPT0=) microprocessor. I found a pinout diagram, which shows that the chip I'm looking at uses 5V (a range of 4.5 to 5.5).

My question is, 5 V..at *what*. Clearly, current does matter as there are much more powerful and higher-clocked ICs running a 1.5 V; and it doesn't take a genius to figure out that connecting it to 12 A would cause it to instantly explode or catch on fire.

Would I be right in assuming that the correct approach would be to measure the resistance and calculate the current using Ohm's law? And if so, how would I go about doing that?