Transparent power management mode, integrated MMU and TTL compatible inputs ( only 386SXSA ).

The designation TTL is sometimes used to mean TTL-compatible logic levels, even when not associated directly with TTL integrated circuits, for example as a label on the inputs and outputs of electronic instruments.

Like DTL, TTL is a current-sinking logic since a current must be drawn from inputs to bring them to a logic 0 level.

TTL inputs are sometimes simply left floating to provide a logical " 1 ", though this usage is not recommended.

TTL is particularly well suited to bipolar integrated circuits because additional inputs to a gate merely required additional emitters on a shared base region of the input transistor.

* Schottky TTL ( S ), introduced in 1969, which used Schottky diode clamps at gate inputs to prevent charge storage and improve switching time.

Although all semiconductors can be damaged by electrostatic discharge, the high impedance of CMOS inputs makes them more susceptible than bipolar transistor-based, TTL, devices.

In contrast to TTL, CMOS uses almost no power in the static state ( that is, when inputs are not changing ).

One major improvement was to combine CMOS inputs and TTL drivers to form of a new type of logic devices called BiCMOS logic, of which the LVT and ALVT logic families are the most important.

TTL logic inputs that are left un-connected inherently float high, thus they require a much lower valued pull-down resistor to force the input low.

The tracert ( traceroute ), Pathping commands are implemented by transmitting UDP datagrams with specially set IP TTL header fields, and looking for ICMP Time to live exceeded in transit ( above ) and " Destination unreachable " messages generated in response.

* The TTL field of IPv4 has been renamed to Hop Limit, reflecting the fact that routers are no longer expected to compute the time a packet has spent in a queue.

They are activated by AC control signals or DC control signals from Programmable logic controller ( PLCs ), PCs, Transistor-transistor logic ( TTL ) sources, or other microprocessor and microcontroller controls.

Nameservers may also have a TTL set for NXDOMAIN ( acknowledgment that a domain does not exist ); but they are generally short in duration ( three hours at most ).

Newer DNS methods that are part of a DR ( Disaster Recovery ) system may have some records deliberately set extremely low on TTL.

For example a 300 second TTL would help key records expire in 5 minutes to help ensure these records are flushed world wide quickly.

TTL values are " per record " and setting this value on specific records is normally honored automatically by all standard DNS systems world-wide.

Mutable ( and therefore unauthenticated ) IPv4 header fields are DSCP / TOS, ECN, Flags, Fragment Offset, TTL and Header Checksum.

TTL chips are now are also made in surface-mount packages.

Successors to the original bipolar TTL logic often are interchangeable in function with the original circuits, but with improved speed or lower power dissipation.

TTL outputs are typically restricted to narrower limits of between 0 V and 0. 4 V for a " low " and between 2. 6 V and 5 V for a " high ", providing 0. 4V of noise immunity.

Designers can combine ECL and TTL devices in the same system to achieve best overall performance and economy, but level-shifting devices are required between the two logic families.

The TTL " totem-pole " output structure often has a momentary overlap when both the upper and lower transistors are conducting, resulting in a substantial pulse of current drawn from the power supply.

V < sub > CC </ sub > and Ground are carryovers from TTL logic and that nomenclature has been retained with the introduction of the 54C / 74C line of CMOS.

The increased low output level can cause troubles when TTL logic circuits are driven.

Schottky metal – semiconductor junctions are featured in the successors to the 7400 TTL family of logic devices, the 74S, 74LS and 74ALS series, where they are employed as clamps in parallel with the collector-base junctions of the bipolar transistors to prevent their saturation, thereby greatly reducing their turn-off delays.

Going on these figures alone TTL logic gates are limited to perhaps 2 to 10, depending on the type of gate, while CMOS gates have DC fan-outs that are generally far higher than is likely to occur in practical circuits ( e. g. using NXP Semiconductor specifications for their HEF4000 series CMOS chips at 25 ° C and 15 V gives a fan-out of 34 thousand ).

The 7400 series of transistor-transistor logic ( TTL ) integrated circuits are historically important as the first widespread family of TTL integrated circuit logic.

An integrated circuit made in CMOS is not a TTL chip since it uses field-effect transistors ( FETs ) and not bipolar junction transistors, but similar part numbers are retained to identify similar logic functions and electrical ( power and I / O voltage ) compatibility in the different subfamilies.

Transistor-transistor logic ( TTL ) then supplanted DTL with the observation that one transistor could do the job of two diodes even more quickly, using only half the space.

Since the invention of the “ solid state ” transistor in the 1950s and the TTL ( transistor-transistor logic ) that led to the development of the IC ( integrated circuit ) in the 1960s the growth in the field of electronics has been phenomenal.

Transistor – transistor logic ( TTL ) is a class of digital circuits built from bipolar junction transistors ( BJT ) and resistors.

TTL circuits simplified design of systems compared to earlier logic families, offering superior speed to resistor – transistor logic ( RTL ) and easier design layout than emitter-coupled logic ( ECL ).

TTL was invented in 1961 by James L. Buie of TRW, " particularly suited to the newly developing integrated circuit design technology ", and it was originally named transistor-coupled transistor logic ( TCTL ).

The 605 / 615 / 625 / 635 and 645 were essentially 2nd Generation Computers with discrete transistor TTL logic and a handful of integrated circuits.

* Bipolar junction transistor ( used in TTL and ECL ) — very fast but consumes a lot of power

However, the foundation that made National successful was its expertise in analogue electronics, TTL ( transistor – transistor logic ) and MOSFET ( metal-oxide-semiconductor field-effect transistor ) integrated circuit technologies.

Furthermore, Fairchild's DTL technology was being overtaken by Texas Instruments's faster TTL ( transistor – transistor logic ).

7400 series parts were constructed using bipolar transistors, forming what is referred to as transistor – transistor logic or TTL.

RTL is the earliest class of transistorized digital logic circuit used ; other classes include diode – transistor logic ( DTL ) and transistor – transistor logic ( TTL ).

A low-voltage diode arranged to prevent saturation of the transistor was applied to integrated logic families by using Schottky diodes, as in Schottky TTL.

It is called so because the logic gating function ( e. g., AND ) is performed by a diode network and the amplifying function is performed by a transistor ( contrast this with RTL and TTL ).

* Transistor – transistor logic ( TTL )