We have built a Shectman-type photon-counting spectrometer based on the Latham-Geary “Z-Machine” design. The system is innovative in that the entire system rides on the telescope and communicates to the outside world via standard serial lines. Microprocessor architecture, memory controllers and new interconnect and packaging technologies have been employed. The system is portable and can be easily connected to almost any computer. It is suitable for calibrated spectrophotometry on a smaller telescope as well as for conventional spectroscopy.