Early VDUs were typically designed for displaying graphical data rather than just text. In the 1960s several vendors had block mode character oriented VDUs, e.g. IBM 2260. In the 1970s relatively inexpensive ASCII character mode terminals, e.g., ADM3A, VT100, were available and were sometimes nicknamed "Glass TTYs" ("glass Teletypes") or "Visual Display Units" (VDUs), and used no CPU, instead relying on individual logic gates or very primitive LSI chips. Nevertheless, they quickly became extremely popular Input-Output devices on many different types of computer system once several suppliers gravitated to a set of common standards: