At the beginning :-)

First. to understand the '51 architecture download, save and read the 3 chapters of the '51 "bible" see links <=== under "other interesting sites". The full "bible" also with a link there is 3 times the size of chs 1-3 and chs 1-3 are the actual "bible", the rest are datasheets for ancient '51s.

Then I suggest you look into www.phytec.com and buy a P89C668 development board. I have done prototypes with this board and had no problems.

It comes with (evaluation - limited) assembler, C compiler and it can download programs directly from the PC.

Erik