We describe the Instrument Control Software (ICS) package that we have built for The Habitable-Zone Planet Finder (HPF) spectrometer. The ICS controls and monitors instrument subsystems, facilitates communication with the Hobby-Eberly Telescope facility, and provides user interfaces for observers and telescope operators. The backend is built around the asynchronous network software stack provided by the Python Twisted engine, and is linked to a suite of custom hardware communication protocols. This backend is accessed through Python-based command-line and PyQt graphical frontends. In this paper we describe several of the customized subsystem communication protocols that provide access to and help maintain the hardware systems that comprise HPF, and show how asynchronous communication benefits the numerous hardware components. We also discuss our Detector Control Subsystem, built as a set of custom Python wrappers around a C-library that provides native Linux access to the SIDECAR ASIC and Hawaii-2RG detector system used by HPF. HPF will be one of the first astronomical instruments on sky to utilize this native Linux capability through the SIDECAR Acquisition Module (SAM) electronics. The ICS we have created is very flexible, and we are adapting it for NEID, NASA's Extreme Precision Doppler Spectrometer for the WIYN telescope; we will describe this adaptation, and describe the potential for use in other astronomical instruments.