Abstract: A thermostat for generating control signals for a furnace, air conditioner, or the like, employs a constant frequency, periodically alternating electrical source and an oscillator incorporating an element having a thermal-sensitive electrical characteristic so the oscillator frequency varies as a function of the ambient temperature. A comparator receives the two outputs and generates a signal representative of the ambient temperature. The stable output is also provided to dividing circuits to generate a signal representative of the time that is used to interrogate a digital memory storing a desired temperature-time program for the thermostat for a repetitive period, such as a week or month. The ambient temperature signal is compared with the desired temperature signal to generate an output control signal. A display provides a read-out of time and temperature and is used along with a keyboard or the like in programming the memory.

Abstract: A thermostatic controller system for a building heating and/or cooling system (furnace) includes a stored program of desired temperatures which are to be attained within the building at predetermined times within a repetitive time cycle, such as a day. Differing environmental conditions externally of the building result in differing rates of change of temperature within the building upon operation of the furnace. In order to determine the optimum time to switch the system on to meet the next programmed increased temperature, the furnace is switched on and then off a short period of time later and the temperature change which results in the building as a result of that transient operation is measured. The time at which the furnace must be switched to attain the next programmed temperature is then determined as a function of the rate of temperature change as determined by the transient switching and the difference between the instantaneous and the future programmed temperature.

Abstract: A computer terminal employs a CRT display, a micro-processor, and a random access memory which both stores character codes for information to be displayed on the CRT screen and serves as working storage for the processor. To generate a line of text across the display the processor loads a memory address counter with the address of a memory location containing the code for the first character of the line. The counter is incremented in timed relation to the generation of the display and sequentially outputs consecutive memory addresses in which the consecutive character codes forming the line are stored. During the generation of the line the activity of the processor is inhibited. Following generation of the line the processor regains access to the RAM and tends to I/O duties or modifies the display memory contents until it passes control of the RAM back to the address counter for generation of another line of display.