8051参考设计，与其他8051的免费IP相比，文档相对较全，Oregano System 提供
This is version 1.3 of the MC8051 IP core.
September 2002: Oregano Systems - Design & Consulting GesmbH
Change history:
- Improved tb_mc8051_siu_sim.vhd to verify duplex operation.
- Corrected problem with duplex operation in file
mc8051_siu_rtl.vhd
