A circuit arrangement improves CPU efficiency by processing data through a FIFO circuit of a UART chip using a CPU adapted to detect, and respond with various options to, the current storage capacity of the FIFO circuit. In one example embodiment, a circuit arrangement includes a universal asynchronous receiver/transmitter (UART) chip having a FIFO circuit and an arithmetic logic unit (ALU) adapted to generate an N-bit variable binary signal, wherein the binary signal varies as a function of a current storage capacity of the FIFO circuit. The circuit arrangement further includes a control circuit communicatively coupled with the UART chip that is adapted to read the N-bit variable binary signal and, in response, to control the data flow through the FIFO circuit.