Assembler programming?

Question

In assembler, is it possible to switch two fieds in three statements without using a temp field or any other storage.

Answer 1

r1 = r1 xor r2
r2 = r1 xor r2
r1 = r1 xor r2

Answer 2

Im not sure what you mean, or what assembly language, but in Intel 8 bit assembly there is a command called XCH which will exchange a byte with whats in the accumulator.
example:
Accumulator = 50
mybyte = 100

XCH A,mybyte

now the accumulator holds 100 and mybyte holds 50