the links provided do list some general rules, but for the '51 there are much more important rules specific to the architecture.

If someone want to transfer this to wicked for public update, feel free

rules for optimum '51 C
1) Take the darn PC hat off. '51 C is not "just c"
2) ALWAYS use the smallest size of a variable that will fit
3) Make counters in loops -- instead of ++ wherever possible
4) Keil has - on request - provided for things like malloc, that does not mean they are "good" it is a disaster in a '51
5) The '51 has very powerful bit instructions - USE THEM. E.g. if a function can return TRUE or FALSE a bit is enough.

Erik