PAL Numbering System
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Understanding PAL Naming Conventions
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Today, we are going to learn about the PAL numbering system. Can anyone tell me what the first component of the name usually indicates?
Is it the number of inputs?
Exactly! The first part is a two-digit number that tells us how many inputs the device can handle. For example, in 'PAL-16L8', '16' represents the number of inputs.
What comes after the number?
Great question! After the number, there's a letter that describes the type of logic output. Can anyone give an example of what this letter might mean?
Does 'L' stand for active LOW outputs?
Correct! 'L' indicates that the device has active LOW outputs. Remember, understanding these letters is crucial for using PAL devices effectively.
To summarize, the number indicates the inputs, and the letter specifies the output type. Keep these two components in mind when working with PAL devices.
Interpreting Output Specifications
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Now, let’s dive deeper into what the output specifications tell us. After the initial letter that indicates the logic type, the rightmost number provides additional information. Who can explain this?
I think it refers to the number of outputs of a particular type?
Correct! It tells us how many outputs of that specific type there are. For example, 'PAL-16R4' has 4 registered outputs.
What’s the significance of having registered outputs compared to active outputs?
Registered outputs are useful for timing controls and data storage. They allow for stable output states during transitions, which can be crucial in complex logic systems.
In summary, understanding both the type and count of the outputs is essential for using PAL effectively.
Decoding Populations of Inputs
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So, students, we've talked about inputs and outputs. Does anyone recall how to interpret the input types based on our designated labels?
The number indicates both dedicated inputs and user-programmable inputs?
That's right! The input number includes dedicated inputs, user-programmable inputs from I/O pins, and any feedback inputs.
So, how many dedicated inputs would a PAL-16L8 have?
PAL-16L8 has 10 dedicated inputs, alongside the user-programmable inputs. Getting these numbers right helps with device planning.
To summarize, accurately interpreting input numbers in the PAL designation is essential for efficient device usage.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
This section outlines the standard PAL numbering system, which utilizes alphanumeric designations to convey significant details about a device's architecture and logic outputs. The discussion includes the importance of input types, output specifications, and how to interpret these designations effectively.
Detailed
PAL Numbering System
The PAL (Programmable Array Logic) numbering system employs an alphanumeric designation for identifying various aspects of PAL devices. This system begins with a two-digit number that denotes the number of inputs the device has, followed by a letter that indicates the output architecture or type. Various letters are used to convey specific configurations, such as active HIGH or LOW outputs and registered outputs. For example, a PAL device denoted as PAL-16L8 would possess 16 inputs and eight active LOW outputs.
Moreover, the designation also includes additional digits indicating the number of outputs, where the rightmost digit describes the type of output logic present. For instance, PAL-16R4 refers to a configuration with registered outputs. The system's structure allows users to understand the capabilities and constraints of different PAL devices through this concise numerical and letter-based code.
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Standard PAL Numbering
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The standard PAL numbering system uses an alphanumeric designation comprising a two-digit number indicating the number of inputs followed by a letter that tells about the architecture/type of logic output.
Detailed Explanation
The PAL numbering system provides a structured way to identify and classify PAL devices based on their inputs and output architecture. The first part consists of a two-digit number that indicates how many input variables the device can handle. This is essential for understanding the capacity and capability of the PAL device. The letter that follows this number denotes the type of logic outputs available. This classification helps engineers and designers choose the right PAL device for their specific needs.
Examples & Analogies
Think of this numbering system like a library classification for books. Just as books are categorized by genre and author to help readers find what interests them, the PAL numbering helps engineers quickly identify the capabilities of the logic device they need.
Output Types in PAL Devices
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Table 9.3 gives an interpretation of different letter designations in use. Another number following the letter indicates the number of outputs.
Detailed Explanation
In the PAL numbering system, the letter designation provides more details about the output type. Each letter corresponds to a specific behavior of the outputs, such as whether they are active high or active low. Following this letter is another number that represents how many outputs the PAL device has. This number is key for understanding how many independent logic signals the device can produce.
Examples & Analogies
Imagine a remote control for your TV. The letters on the remote could represent which functions there are (like volume or channel), and the number might show how many TVs it could control at once. Similarly, the PAL system helps indicate how many output options an engineering device has.
Examples of PAL Designations
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For example, a PAL device designated PAL-16L8 will have 16 inputs and eight active LOW outputs. Another PAL device designated PAL-16R4 has 16 inputs and four registered outputs.
Detailed Explanation
These examples illustrate how the designation conveys both the number of inputs and the type of outputs. The 'L' in PAL-16L8 indicates that the outputs are active low, meaning they produce a low signal when activated. The 'R' in PAL-16R4 indicates registered outputs, which can hold or latch data based on clock signals. This specification helps users choose the right device based on their requirements for input capacity and output behavior.
Examples & Analogies
Consider ordering coffee at a café. You might specify both the size of the drink (number of inputs) and whether you want it iced or hot (type of output). Similarly, the PAL designation includes both the input capacity and the type of output to ensure it meets specific needs.
Inputs in PAL Devices
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Also, the number of inputs as given by the number designation includes dedicated inputs, user-programmable inputs accessible from combinational I/O pins, and any feedback inputs.
Detailed Explanation
The input count in the PAL designation comprises all types of inputs that are available for use in logic functions. Dedicated inputs are fixed connections on the device, while user-programmable inputs can be configured for a variety of applications. Feedback inputs allow for a more dynamic interaction within circuits, enhancing the complexity of logic operations that the device can undertake.
Examples & Analogies
Imagine a multi-tool that offers various attachments. Each attachment represents an input type—some are fixed (dedicated inputs), some can be adjusted for different tasks (user-programmable inputs), and some can be used to connect to other tools (feedback inputs). This flexibility makes the PAL devices versatile for different applications.
Indication of Technology and Power Level
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In addition to the numbering system described above, an alphanumeric designation on the extreme left may be used to indicate the technology used. ‘C’ stands for CMOS, ‘10H’ for 10KH ECL and ‘100’ for 100K ECL. TTL is represented by a blank. A letter on the extreme right may be used to indicate the power level, with ‘L’ and ‘Q’ respectively indicating low and quarter power levels and a blank representing full power.
Detailed Explanation
This part of the PAL designation provides information regarding the underlying technology that the device uses, which can affect performance characteristics like speed and power consumption. The letters indicate the technology type, providing insights into the operational parameters of the device. The power level notation helps the user understand how much energy the device requires during operation, important for integrating it into power-sensitive applications.
Examples & Analogies
Think of the different types of fuel a car can use, like unleaded or diesel. Just as a driver needs to know what type of fuel is best for their vehicle to ensure optimal performance, engineers must understand the technology and power levels of PAL devices to achieve the best results in their projects.
Key Concepts
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PAL Numbering System: An alphanumeric designation detailing a PAL device's input count and output type.
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Input Count: The first two digits in a PAL designation indicate the number of inputs.
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Output Type: Letters in the designation describe output characteristics, such as active HIGH or LOW.
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Registration and Outputs: The rightmost numbers indicate specific types of outputs available in the device.
Examples & Applications
A PAL-16L8 device has 16 inputs with 8 active LOW outputs.
A PAL-16R4 device can be recognized by having 16 inputs and 4 registered outputs.
Memory Aids
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Rhymes
In PAL naming, hear the tale, Inputs first then types prevail.
Stories
Imagine a factory where each device is marked with numbers and letters. The first two digits tell how many workers it can handle, while the letters share how they operate in the factory.
Memory Tools
I = Inputs; L = LOW outputs; H = HIGH outputs; R= Registered outputs.
Acronyms
P.A.L. - Programmable Architecture Logic.
Flash Cards
Glossary
- PAL
Programmable Array Logic, a type of programmable logic device used to implement combinational logic circuits.
- Active HIGH Outputs
Outputs that provide a true signal when activated.
- Active LOW Outputs
Outputs that provide a true signal in the absence of voltage (logic low).
- Registered Outputs
Outputs that are synchronized to a clock signal, allowing more stable transitions in logic circuits.
- Dedicated Inputs
Inputs that are fixed and not programmable by the user.
- UserProgrammable Inputs
Inputs that can be configured by the user as required for the specific application.
Reference links
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