The category of early microcomputers encompasses the microprocessor-based development system/hobbyist microcomputers being made and sold as "DIY" kits or pre-built machines in relatively small numbers in the mid-1970s, before the advent of the later, simpler to operate, significantly hotter-selling home computers (listed in its own category). Most early micros came without keyboards or displays, which had to be provided by the user, usually at great expense. RAM was typically 4–16 KB.