Complex sentence: The 77/68 was offered for sale by Bear Microcomputer Systems of Maidenhead, Berkshire, England from June, 1977: among the first, if not the first of British home computers.
Split into simpler sentences: The 77/68 was offered for sale by Bear Microcomputer Systems of Maidenhead, Berkshire, England from June, 1977. It was among the first, if not the first, of British home computers.