If you're interested in learning assembly language, I recommend checking out "Programming from the Ground Up" by Jonathan Bartlett [0]. It's a great introduction to ASM and how computers work at the low level. It's also used in universities such as Princeton to teach introductory CS classes [1]. Definitely worth checking out.

[0] http://savannah.spinellicreations.com//pgubook/ProgrammingGr... [1] https://discuss.fogcreek.com/joelonsoftware5/default.asp?cmd...