Look at this:

http://www.pjrc.com/tech/8051/pm2_docs/minimal.gif

insert the T89C51RD2 instead the 78C51 and add a jumper from PSEN to GND to enter the programming mode.

Download the Flip software from Atmel and ready was the cheapest 8051 development system.

Download e.g. the Metalink assembler to write programs for it.


Peter