as TTL with Schottky diodes, some of the underlying circuits, such as used in the LS family, could rather be considered DTL. Variations of and successors to the basic TTL family, which has a typical gate propagation delay of 10ns and a power dissipation of 10 mW per gate, for a power–delay product (PDP) or switching energy of about 100 pJ, include: Low-power TTL (L), which traded switching speed (33ns) for a reduction in power consumption (1 mW) (now essentially replaced by CMOS logic) High-speed TTL (H), with faster switching than standard TTL (6ns) but significantly higher power dissipation (22 mW) Schottky TTL (S), introduced in 1969, which used Schottky diode clamps at gate inputs to prevent charge storage and improve switching time. These gates operated more quickly (3ns) but had higher power dissipation (19 mW) Low-power Schottky TTL (LS) – used the higher resistance values of low-power TTL and the Schottky diodes to provide a good combination of speed (9.5ns) and reduced power consumption (2 mW), and PDP of about 20 pJ. Probably the most common type of TTL, these were used as glue logic in microcomputers, essentially replacing the former H, L, and S sub-families. Fast (F) and Advanced-Schottky (AS) variants of LS from Fairchild and TI, respectively, circa 1985, with "Miller-killer" circuits to speed up the low-to-high transition. These families achieved PDPs of 10 pJ and 4 pJ, respectively, the lowest of all the TTL families. Low-voltage TTL (LVTTL) for 3.3-volt power supplies and memory interfacing. Most manufacturers offer commercial and extended temperature ranges: for example Texas Instruments 7400 series parts are rated from 0 to 70 °C, and 5400 series devices over the military-specification temperature range of −55 to +125 °C. Special quality levels and high-reliability parts are available for military and aerospace applications. Radiation-hardened devices (for example from the SNJ54 series) are offered for space applications. Applications Before the advent of VLSI devices, TTL integrated circuits were a standard method of construction for the processors of minicomputer and mainframe computers; such as the DEC VAX and Data General Eclipse, and for equipment such as machine tool numerical controls, printers and video display terminals. As microprocessors became more functional, TTL devices became important for "glue logic" applications, such as fast bus drivers on a motherboard, which tie together the function blocks realized in VLSI elements. The Gigatron TTL is a more recent (2018) example of a