* 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.

Frequently starting with a value like 128 ( Windows ) or 64 ( Linux ), routers decrement this and discard a packet when the TTL value has reached zero, returning the ICMP error message ICMP Time Exceeded.

If a stub resolver queries the caching nameserver for the same record before the TTL has expired, the caching server will simply reply with the already cached resource record rather than retrieve it from the authoritative nameserver again.

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.

Compared to contemporary ECL circuits, TTL uses less power and has easier design rules but is substantially slower.

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.

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:

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.

TTL has been used on a range of other Mazda vehicles before and since the MX-3.

TTL introduced a new brew, Taiwan Beer Gold Medal, by the end of its first year and has since introduced three more brews: Taiwan Beer Draft ( another lager, for sale in restaurants ) and two malt beers under the Mine label ( Amber and Dark ).

Any and all signals inside a device that has RS232 connectivity are always TTL level ( 0 and 5V or 0 and 3. 3V or 0 and 3v ) internally and conversion to and from RS232 is the last thing outgoing data does, or the first thing incoming data does.

They form a replacement for TTL, although HCT is slower than original TTL ( HC logic has about the same speed as original TTL ).

The shutter dial of the M6 TTL is reversed from previous models, turning in the same direction as the light meter arrows in the viewfinder ; this feature has continued in the M7, M8, and M9, but not the MP, which returned to the older, smaller diameter, opposite direction shutter speed dial.

This switch in the TTL approach has shifted its emphasis more towards BTL.

Each node, upon receiving a RouteRequest packet, rebroadcasts the packet to its neighbors if it has not forwarded it already, provided that the node is not the destination node and that the packet ’ s time to live ( TTL ) counter has not been exceeded.

It has a voltage swing between 0. 4 volts and 1. 2 volts — much lower than that used in TTL and CMOS logic — and symmetrical parallel resistive termination.

A TTL value of 86400 would mean that, if a DNS record was changed on the authoritative nameserver, DNS servers around the world could still be showing the old value from their cache for up to 24 hours after the change.

* High-speed TTL ( H ), with faster switching than standard TTL ( 6ns ) but significantly higher power dissipation ( 22 mW )

TTL became popular with electronic systems designers after Texas Instruments introduced the 5400 series of ICs, with military temperature range, in 1964 and the later 7400 series, specified over a narrower range, and with inexpensive plastic packages in 1966.

The term " TTL " is applied to many successive generations of bipolar logic, with gradual improvements in speed and power consumption over about two decades.

This is a critical advantage of TTL over DTL that speeds up the transition over a diode input structure.

Standardization of the TTL levels was so ubiquitous that complex circuit boards often contained TTL chips made by many different manufacturers selected for availability and cost, compatibility being assured ; two circuit board units off the same assembly line on different successive days or weeks might have a different mix of brands of chips in the same positions on the board ; repair was possible with chips manufactured years ( sometimes over a decade ) later than original components.

This effect is less marked for TTL systems, which is one reason why they maintained a speed advantage over CMOS for many years.

Later, the HP300 design team over came the first generation HP300 slower TTL circuitry with a SOS design ( project name: Sizzler ).

These services can include voice ( plain old telephone service ( POTS ) or voice over IP ( VoIP )), data ( typically Ethernet or V. 35 ), video, and / or telemetry ( TTL, ECL, RS530, etc.

Some resolvers may override TTL values, as the protocol supports caching for up to 68 years or no caching at all.

In addition, Commodore made the drive's controller board smaller and having a lower chip count than the early 1541s ( which had a large PCB with dozens of TTL chips running the length of the case ).

The time for which a resolver caches a DNS response is determined by a value called the time to live ( TTL ) associated with every record.

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.

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.

Initially a 32-bit TTL processor in conjunction with supporting microcode implemented the programmer-visible architecture.

A dedicated voltage comparator chip such as LM339 is designed to interface with a digital logic interface ( to a TTL or a CMOS ).

The first SLR cameras with internal (“ through-the-lens ” or “ TTL ”) meters ( e. g., the Pentax Spotmatic ) required that the lens be stopped down to the working aperture when taking a meter reading.

A Motorola 68000-based computer with various TTL chips mounted on protoboard s.

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.

After introduction in integrated circuit form in 1963 by Sylvania, TTL integrated circuits were manufactured by several semiconductor companies, with the 7400 series by Texas Instruments becoming particularly popular.

Several variations from the original bipolar TTL concept were developed, giving circuits with higher speed or lower power dissipation to allow optimization of a design.

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

Two-input TTL Sheffer stroke # NAND gate | NAND gate with a simple output stage ( simplified ).

The main disadvantage of TTL with a simple output stage is the relatively high output resistance at output logical " 1 " that is completely determined by the output collector resistor.

Standard TTL NAND with a " totem-pole " output stage, one of four in 7400

The main advantage of TTL with a " totem-pole " output stage is the low output resistance at output logical " 1 ".

Standard TTL circuits operate with a 5-volt power supply.