1. In a data processing system comprising a memory having a plurality of storage locations for storing data and instructions and a processor for executing such instructions, a method of executing a conditional branch instruction, said instruction comprising an op code and a bit number, a first address portion designating a first storage location in said memory, and a second address portion designating a second storage location in said memory, said method comprising the steps of: fetching the data stored in said first storage location using said first address portion of said instruction; testing the state of the bit in the data fetched from said first storage location corresponding to said bit number; and branching to said second storage location using said second address portion of said instruction if said bit is in a predetermined state.