The 488 Controller converts a host RS-232 or RS-422 computer into an IEEE 488 bus talker, listener and controller. The 488 Controller provides full IEEE 488-1978 bus implementation including advance capabilities such as PASS CONTROL, RECEIVE CONTROL, PARALLEL POLL, SERIAL POLL and SECONDARY ADDRESSING. The device may be located several hundred feet from the host and may control as many as fourteen 488 bus instruments. In the noncontroller mode the 488 Controller converts the host into a bus peripheral for data processing and mass storage. The 488 Controller interprets simple high-level commands sent from the computer’s serial port and performs the necessary, and usually complex, bus control and handshaking. The commands and protocol are similar to those used by the Hewlett-Packard® HP-85 computer. Additional features provide a transparent IEEE to serial converter and a serial to IEEE pass-thru controller. As a serial-to-IEEE-488 converter, the 488 Controller receives data from a serial host, then automatically performs the bus sequences necessary to send this data to the IEEE 488 device. If desired, data can be requested from the IEEE 488 device and returned to the host. As an IEEE-488-to-serial converter, the 488 Controller is a peripheral to an IEEE 488 controller. Data received from the controller is sent to the serial device and data received from the serial device is buffered for transmission to the IEEE 488 controller. The 488 Controller can inform the host, by the serial poll-status byte, that it has received data from the serial device.