Many logic families were produced as individual components, each containing one or a few related basic logical functions, which could be used as “building-blocks” to create systems or as so-called “glue” to interconnect more complex integrated circuits. Before the widespread use of integrated circuits, various solid-state and vacuum-tube logic systems were used but logic gates using diodes and transistors pdf were never as standardized and interoperable as the integrated-circuit devices.
For example, early digital clocks or electronic calculators may have used one or more PMOS devices to provide most of the logic for the finished product. Of these families, only ECL, TTL, NMOS, CMOS, and BiCMOS are currently still in widespread use. CPUs and memory chips which fall outside of the scope of this article. Present-day “building block” logic gate ICs are based on the ECL, TTL, CMOS, and BiCMOS families. RTL, where it was implemented using discrete components. A variant with integrated capacitors, RCTL, had increased speed, but lower immunity to noise than RTL.
This was made by Texas Instruments as their “51XX” series. Early transistorized computers were implemented using discrete transistors, resistors, diodes and capacitors. 1962, but these devices were not available to the public. 1 and logic 0 voltage levels.
These devices usually ran off a 15 volt power supply and were found in industrial control, where the high differential was intended to minimize the effect of noise. TTL has changed significantly over the years, with newer versions replacing the older types. Since the transistors of a standard TTL gate are saturated switches, minority carrier storage time in each junction limits the switching speed of the device. Variations on the basic TTL design are intended to reduce these effects and improve speed, power consumption, or both. Gates built with Schottky transistors use more power than normal TTL and switch faster.
It was used in some integrated circuits, but it is now considered obsolete. A CMOS gate draws no current other than leakage when in a steady 1 or 0 state. When the gate switches states, current is drawn from the power supply to charge the capacitance at the output of the gate. Initially CMOS logic was slower than LS-TTL. However, because the logic thresholds of CMOS were proportional to the power supply voltage, CMOS devices were well-adapted to battery-operated systems with simple power supplies. The required silicon area for implementing such digital CMOS functions has rapidly shrunk.