In case you're using latest and the new UI, on the left there should be a selector for various options:



Using the mouse and clicking on available should do the trick.

This topic will be dedicated to any external tutorial worth of interest for getting a more accurate emulation. Will be updated from time to time.

Analog Video 101
http://www.ni.com/white-paper/4750/en/#toc1

z80 Assembler Directives
http://www.nongnu.org/z80asm/directives.html