I introduce the C64 memory map by way of tracing the circuits used to activate the VIC-II for reads and writes.

C64 Schematic I used: http://www.commodore.ca/manuals/funet/cbm/schematics/computers/c64/manual/c64-22r.gif

decoder datasheet: http://pdf.datasheetcatalog.com/datasheets/270/331333_DS.pdf