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Direct-coupled transistor logic
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Direct-coupled transistor logic
Direct-coupled transistor logic (DCTL) is similar to resistor–transistor logic (RTL), but the input transistor bases are connected directly to the collector outputs without any base resistors. Consequently, DCTL gates have fewer components, are more economical, and are simpler to fabricate onto integrated circuits than RTL gates. Unfortunately, DCTL has much smaller signal levels, has more susceptibility to ground noise, and requires matched transistor characteristics. The transistors are also heavily overdriven; this is a good feature in that it reduces the saturation voltage of the output transistors, but it also slows the circuit down due to a high stored charge in the base. Gate fan-out is limited due to "current hogging": if the transistor base–emitter voltages (VBE) are not well matched, then the base–emitter junction of one transistor may conduct most of the input drive current at such a low base–emitter voltage that other input transistors fail to turn on.
DCTL is close to the simplest possible digital logic family, using close to fewest possible components per logical element.
A similar logic family, direct-coupled transistor–transistor logic, is faster than ECL.
John T. Wallmark and Sanford M. Marcus described direct-coupled transistor logic using JFETs. It was termed direct-coupled unipolar transistor logic (DCUTL). They published a variety of complex logic functions implemented as integrated circuits using JFETs, including complementary memory circuits.
DCTL is a catalyst for other transistors which are very convenient to use. They were made 65 years ago[when?] and have many updated and different variations of them today. One of the more recent and used today is called transistor–transistor logic (TTL) and resistor–transistor logic (RTL). TTL functions similarly to DCTL, except DCTL has lower signal levels and is sensitive to ground noise, while TTL depends more on polarity. DCTLs are not used as much as they were in the past. RTL also focuses heavily on polarity, specifically being a bipolar transistor switch. They are still very important and changed the history of audio and are the fundamental stepping stones to creating higher-quality inventions.[buzzword]
A DCTL circuit has three logical functions: AND gating, OR gating, and signal inversion (NOT gating). Each of these functions is the building block of what creates the circuit board. An AND gate requires two or more inputs that are true for there to be an outcome. As an example, let's say that 1 and 2 are true and 0 is false the only way for there to be an output is for the input to contain either 1,2, or both[clarify]. If any of the inputs are 0, there will be no output. All inputs must be true for there to be an output. OR gating also requires two or more inputs, but unlike AND gating, only one of the inputs is required to be true. The NOT gate only needs a single input, so there could be an output. Therefore, if the single input is not true, there will be no output. With these three gates, many other logical functions can be made with them making the possibilities endless.
A DCLT is known for doing three functions:
Each of these functions makes the output voltage supply low, so it does not have a negative impact on the other circuits in the machine.Each of these functions lowers the output voltage supply to prevent any negative impact on the other circuits in the machine.,[clarification needed][clarification needed]
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Direct-coupled transistor logic AI simulator
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Direct-coupled transistor logic
Direct-coupled transistor logic (DCTL) is similar to resistor–transistor logic (RTL), but the input transistor bases are connected directly to the collector outputs without any base resistors. Consequently, DCTL gates have fewer components, are more economical, and are simpler to fabricate onto integrated circuits than RTL gates. Unfortunately, DCTL has much smaller signal levels, has more susceptibility to ground noise, and requires matched transistor characteristics. The transistors are also heavily overdriven; this is a good feature in that it reduces the saturation voltage of the output transistors, but it also slows the circuit down due to a high stored charge in the base. Gate fan-out is limited due to "current hogging": if the transistor base–emitter voltages (VBE) are not well matched, then the base–emitter junction of one transistor may conduct most of the input drive current at such a low base–emitter voltage that other input transistors fail to turn on.
DCTL is close to the simplest possible digital logic family, using close to fewest possible components per logical element.
A similar logic family, direct-coupled transistor–transistor logic, is faster than ECL.
John T. Wallmark and Sanford M. Marcus described direct-coupled transistor logic using JFETs. It was termed direct-coupled unipolar transistor logic (DCUTL). They published a variety of complex logic functions implemented as integrated circuits using JFETs, including complementary memory circuits.
DCTL is a catalyst for other transistors which are very convenient to use. They were made 65 years ago[when?] and have many updated and different variations of them today. One of the more recent and used today is called transistor–transistor logic (TTL) and resistor–transistor logic (RTL). TTL functions similarly to DCTL, except DCTL has lower signal levels and is sensitive to ground noise, while TTL depends more on polarity. DCTLs are not used as much as they were in the past. RTL also focuses heavily on polarity, specifically being a bipolar transistor switch. They are still very important and changed the history of audio and are the fundamental stepping stones to creating higher-quality inventions.[buzzword]
A DCTL circuit has three logical functions: AND gating, OR gating, and signal inversion (NOT gating). Each of these functions is the building block of what creates the circuit board. An AND gate requires two or more inputs that are true for there to be an outcome. As an example, let's say that 1 and 2 are true and 0 is false the only way for there to be an output is for the input to contain either 1,2, or both[clarify]. If any of the inputs are 0, there will be no output. All inputs must be true for there to be an output. OR gating also requires two or more inputs, but unlike AND gating, only one of the inputs is required to be true. The NOT gate only needs a single input, so there could be an output. Therefore, if the single input is not true, there will be no output. With these three gates, many other logical functions can be made with them making the possibilities endless.
A DCLT is known for doing three functions:
Each of these functions makes the output voltage supply low, so it does not have a negative impact on the other circuits in the machine.Each of these functions lowers the output voltage supply to prevent any negative impact on the other circuits in the machine.,[clarification needed][clarification needed]
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