The Message store is divided into a working store and a memory store. The text which is typed on the keyboard is stored in the working store. The text can be recalled to the display for editing. After the encryption (or decryption) the encrypted (decrypted) version of the text is replacing the text in the working store. Any text in this store can be transferred to the memory store. There is an internal key store capable of storing 9 different keyvariables. PACE has a built-in acoustical modem which can automatically transfer messages at high speed from one PACE to another via any voice grade circuit. An error correcting code is part of the system. An optical modem is also included, making electrical interface to various types of communication and printing equipment possible. PACE is powered by one 9 Volt Alkaline battery. The battery will last For approximately 24 hours of accumulated use. A 3.4 Volt lithium Battery will keep keys and communications parameters alive during change of the main battery. The lifetime is 5 years.