Memotech
Memotech was a company based in Witney in Oxfordshire, England. They started out during the early 1980s producing memory expansion packs ("RAMpacks") and other hardware expansions for the Sinclair ZX81.
However, they eventually went on to develop and sell their own MTX family of computers which included the following models: MTX500, MTX512 and RS128.
Although well-regarded, these computers were not commercially successful, and the company went into receivership in 1985.