Complex sentence: As the ZX Spectrum became hugely popular, the lack of a mass storage system became a problem for more serious users and while Sinclair's response, the ZX Interface 1 and ZX Microdrive, while very cheap and technologically innovative, was also rather limited.
Split into simpler sentences: As the ZX Spectrum became hugely popular, the lack of a mass storage system became a problem for more serious users. While Sinclair's response, the ZX Interface 1 and ZX Microdrive, was very cheap and technologically innovative, it was also rather limited.