Wired Logic Gates: Exploring the Limitations and Velocity Factors

In summary, a wired-logic gate does not produce a physical second-level gate because it was mainly to reduce cost, but also due to the velocity of the components used to create the "wired-connection". This was done by wiring together several collectors which created the AND and NAND functions. This allowed for gates to have only one input but many identical outputs. This concept was also used in communication schemes such as Ethernet and CAN for collision detection and avoidance purposes.
  • #1
themagiciant95
57
5
Hi, why a wired-logic gate does not produce a physical second-level gate ? Is it due to the velocity of the components that create the "wired-connection" ?
Thanks
 
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  • #2
themagiciant95 said:
Is it due to the velocity of the components that create the "wired-connection" ?
Partly, but mainly to reduce cost.
When transistors were expensive, several collectors were wired together. If anyone collector sank current the wire was pulled to a low voltage, making the AND function. The next transistor inverted the signal which made the NAND function.
https://en.wikipedia.org/wiki/Wired_logic_connection

That created the interesting situation where gates needed only one input, but had many identical outputs.
https://en.wikipedia.org/wiki/Integrated_injection_logic
 
  • #3
The wired-and function are also used in some communication schemes where the outputs are far apart. In the original Ethernet the signal was put onto the wire using a wired-or connection. The signal receiver continuously monitored the signal on the wire and if the signal on the wire was different from the expected value, the conclusion was that more than one transmitter tried to send at the same time - a collision.

A similar mechanism is used in CAN, but not for collision detection but collision avoidance.
 

1. What is a wired logic connection?

A wired logic connection is a type of electronic connection used in digital systems to transfer signals between different components. It involves physically connecting wires between the input and output of logic gates to create a specific logic function.

2. How is wired logic different from other types of connections?

Wired logic is different from other types of connections, such as printed circuit boards, because it does not use any intermediary components like transistors or resistors. Instead, it relies on the physical connection of wires to create logical functions.

3. What are the advantages of using wired logic connections?

One advantage of wired logic connections is their simplicity and low cost. They also have a fast response time and are more robust compared to other types of connections. Additionally, wired logic can be easily modified or reconfigured by changing the physical connections, making it a flexible option for digital systems.

4. What are the limitations of wired logic connections?

One limitation of wired logic connections is that they can become complex and difficult to manage in larger systems, leading to potential errors and malfunctions. They also require physical space for the wires, making them less suitable for miniaturization or compact designs.

5. Where are wired logic connections commonly used?

Wired logic connections are commonly used in simple digital systems, such as household appliances, calculators, and other consumer electronics. They are also used in industrial and automotive applications, where reliability and cost-effectiveness are important factors.

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