The problem here is the magical word ARRAY.

When you create an array the compiler MUST use math to figure out the location of BIT_ARRAY[23]. This is EASY for the compiler.

However, the 8051 does not have an instruction that lets you set a bit based on an index. You only have SETB and CLR. And, these instructions REQUIRE a fixed address. This should also explain why pointers to bits aren't supported. It's impossible!

I guess that a self-modifying program could be created. However, that means that you must have some von Neumann RAM in your architecture. And, few 8051 systems incorporate that.

Jon Ward
Keil Software