For example SN74ALS245N means this is a device probably made by Texas Instruments ( SN ), it is a commercial temperature range TTL device ( 74 ), it is a member of the " advanced low-power Schottky " family ( ALS ), and it is a bi-directional eight-bit buffer ( 245 ) in a plastic through-hole DIP package ( N ).

Normal TTL signals are single-ended, which means that each signal consists of a voltage on one wire, referenced to a system ground.

* A TTL of 1 means you only can ask the peers you know and they cannot ask further.

Ethernet does not have a time to live ( TTL ) field in its frame header, so loop avoidance must be arranged by other means.

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.

RFC 1912 conveys basic rules for determining appropriate TTL values.

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

The value of the MINIMUM field of the SOA record and the TTL of the SOA itself is used to establish the TTL for the negative answer.

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.

When a caching ( recursive ) nameserver queries the authoritative nameserver for a resource record, it will cache that record for the time ( in seconds ) specified by the TTL.

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.

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 ).

An older common TTL value for DNS was 86400 seconds, which is 24 hours.

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.

* Gnutella TTL and Hops header values used for preventing loops and monitoring of network topology

The circuit diagram for a 4 bit Transistor-transistor logic | TTL counter, a type of state machine

TTL is notable for being a widespread integrated circuit ( IC ) family used in many applications such as computers, industrial controls, test equipment and instrumentation, consumer electronics, synthesizers, etc.

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.

At least one manufacturer, IBM, produced non-compatible TTL circuits for its own use ; IBM used the technology in the IBM System / 38, IBM 4300, and IBM 3081.

TTL also became important because its low cost made digital techniques economically practical for tasks previously done by analog methods.

The Kenbak-1, ancestor to the first personal computers, used TTL for its CPU instead of a microprocessor chip, which was not available in 1971.

The maximum value of this current is about 1. 6 mA for a standard TTL gate.

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.

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.

In some cases ( e. g., when the output of a TTL logic gate needs to be used for driving the input of a CMOS gate ), the voltage level of the " totem-pole " output stage at output logical " 1 " can be increased up to V < sub > CC </ sub > by connecting an external resistor between the V < sub > 3 </ sub > collector and the positive rail.

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.

While originally designed to handle logic-level digital signals, a TTL inverter can be biased as an analog amplifier.

TTL inverters can also be used in crystal oscillators where their analog amplification ability is significant.

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

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.

The tick-mark here represents the omitted subfamily designator -- most commonly HC ( high-speed CMOS ), but can also be blank ( original TTL ), C ( CMOS ), LS ( low-power Schottky ), and many others.

Another more advanced method is to attach a TTL to the modem's RS-232 adapter, and get access to the modem's console directly to make it download new firmware, which can then be configured via a simple web interface.

This arrangement is less used today than during the 1970s ; it can be implemented with few transistors ( not so important today ) but is relatively difficult to balance and so keep to a low distortion ( the highly non-linear TTL circuits such as the 7400 use this arrangement ).

The PALM processor was an entire circuit board containing 13 square metal-can bipolar gate arrays, 3 conventional DIP transistor-transistor logic ( TTL ) parts and 1 round metal can part.

CMOS gates can also tolerate much wider voltage ranges than TTL gates because the logic thresholds are ( approximately ) proportional to power supply voltage, and not the fixed levels required by bipolar circuits.

In the DUNDi configuration one can limit the number of consecutive lookups between peers by setting the TTL.

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.

A host can clear its announcement to a network by sending a response packet with a Time To Live ( TTL ) equal to zero.

While filtering and MD5 / TTL protection is already available for most BGP implementations ( thus preventing the source of most attacks ), the problem stems from the concept that ISPs rarely ever filter advertisements from other ISPs, as there is no common or efficient way to determine the list of permissible prefixes each AS can originate.

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

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.

It was their only 18-bit machine constructed from TTL integrated circuits rather than discrete transistors, and had an optional integrated vector graphics terminal.

The ZX80 was designed around readily available TTL chips ; the only proprietary technology was the firmware.

Not only did others make compatible TTL parts, but compatible parts were made using many other circuit technologies as well.

For example, the HP 59501 Power Supply Programmer and HP 59306A Relay Actuator were both relatively simple HP-IB peripherals implemented only in TTL logic, using no microprocessor.

Of these families, only ECL, TTL, NMOS, CMOS, and BiCMOS are currently still in widespread use.

* RS232 port is also included, but even most of Dell's employees don't know this fact and the port only supplies TTL signal level.

TTL logic circuitry determines the highest fret segment making contact on each string, and prevents simultaneous organ notes on the same string to activate ; only the highest organ note played on a particular string will sound.

The TTL field is 8 bits, its only metric is hop count.