The Pentium brand name initially referred only to the fifth-generation microarchitecture of microprocessors from Intel, called Intel P5 and described here, but later it covered also subsequent generations. So, the Pentium as Intel P5, considered here, was a successor to the 486 line, and was first shipped on March 22, 1993. The Pentium was expected to be named 80586 or 1586, to follow the naming convention of previous generations. However, Intel was unable to persuade a court to allow them to trademark a number (such as 486), in order to prevent competitors such as Advanced Micro Devices from branding their processors with similar names (such as AMD's Am486).