A data processing system which includes a floating point computation unit (FPU) which interfaces with a central processing unit (CPU) in which the CPU supplies a dispatch control signal to inform the FPU that it is about to execute a floating point macroinstruction and supplies a dispatch address which includes the starting address of the floating point microinstructions therefor during the same operating cycle that the dispatch control signal is supplied. A buffer memory is provided in the FPU to store the starting address of one decoded macroinstruction while a sequence of microinstructions for a previously decoded macroinstruction is being executed by the FPU. When the buffer already has a starting address resident in its buffer the FPU supplies a control signal to prevent the CPU from supplying a further dispatch address until the buffer is empty. Other control signals for synchronizing the CPU and FPU operations and data transfers are also provided.