Complex sentence: World of Spectrum is a website devoted to cataloging and archiving material for the ZX Spectrum home computer popular in the 1980s, and has been officially endorsed by Amstrad which holds the rights to the ZX Spectrum brand.
Split into simpler sentences: World of Spectrum was a website devoted to cataloging and archiving material for the ZX Spectrum home computer popular in the 1980s. It was officially endorsed by Amstrad which holds the rights to the ZX Spectrum brand.