Sinclair's first personal computer with a colour display. The Spectrum used the Zilog Z80 processor like its predecessors the ZX-80 and ZX-81. It was originally available in 16k and 48k versions using cassette tape and later grew to 128k and sprouted floppy disks. It had a wider and more solid case and a marginally better "dead flesh" keyboard. Unlike the earlier models, it didn't require the presence of a cold carton of milk to prevent it overheating. It was possibly the most popular home computer in the UK for many years. The TK-90X was a clone.