This is a collection of online sources of info I've found about the Z80

* General Z80
http://www.z80.info


* Undocumented Z80
http://z80.info/zip/z80-documented.pdf The undocumented Z80 by Sean Young
http://www.worldofspectrum.org/z88forever/dn327/z80undoc.htm  Undocumented 

* Other Z80 emu
http://www.mathematik.uni-ulm.de/users/ag/yaze-ag/
http://fms.komkon.org/
https://floooh.github.io/2017/12/10/z80-emu-evolution.html


* tests
http://www.jeffavery.ca/computers/macintosh_z80exerciser.html


* Info about old ASM directives
http://48k.ca/zmac.html
http://www.mathematik.uni-ulm.de/users/ag/yaze-ag/
http://www.winape.net/help/macros.html