Questions and Answers
What is a fundamental component used as memory in small applications?
Which operation is performed to transfer data from a memory location to the output line?
What does memory access time measure?
How is memory capacity typically expressed?
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What type of memory is generally used for storing large amounts of data externally?
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What is the purpose of address lines in a memory system?
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Which type of ROM can be programmed only once after fabrication?
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Which statement best describes the characteristics of EPROM?
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What is the main advantage of using bipolar ROM technology?
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What does word length refer to in terms of CPU?
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Study Notes
Memory
- Essential for storing information in digital systems, including instructions and data.
- Types of memory: flip-flops and registers for small applications; semiconductor memory chips for microprocessors; magnetic memory (tapes, hard disks) for large data storage.
- Magnetic memories are external to the digital system.
Basic Terms in Memory
- Memory Read: Transfers data from a specific memory location to output; requires addressing and activating the Read control line.
- Memory Write: Transfers data to a specified memory location; involves addressing, activating the Write control line, and applying data to the input line.
- Access Time: Time to store or read data from a memory location.
- Memory Capacity: Maximum information retention, measured in KB, MB, GB, TB.
- Address Lines: Unidirectional lines indicating memory location; point to one location at a time.
- Word Length: Number of bits processed simultaneously, e.g., a 16-bit CPU processes 16 bits at once.
Read-Only Memory (ROM) and Types
- ROM: Non-volatile semiconductor memory for permanent data storage.
- Advantages: Low cost, high speed, flexibility, and data persistence.
- Types of ROM:
- Mask Programmable ROM: Data programmed at fabrication; immutable post-manufacturing.
- Programmable ROM (PROM): User-programmable after fabrication; one-time programmable.
- Erasable Programmable ROM (EPROM): User-programmable and erasable using ultraviolet light.
- Electrically Erasable PROM (EEPROM): Allows electrical erasing and reprogramming of individual words.
- Flash ROM: Stores data in memory cells with floating gate transistors; allows block writing and erasing.
Random Access Memory (RAM) and Types
- RAM: Read/write memory allowing dynamic data alteration during system operation.
- Types of RAM:
- Static RAM (SRAM): Uses flip-flops for storage; faster and more expensive; no refresh needed.
- Dynamic RAM (DRAM): Uses capacitors and transistors; more dense and cost-effective; common in computer main memory.
- Solid State Drives (SSDs) utilize NAND flash memory for permanent data storage without moving parts, replacing traditional hard disk drives (HDDs).
Fixed Logic vs. Programmable Logic
- Fixed Logic: Devices like gates and flip-flops perform predefined functions; fixed structure post-manufacture; longer design-to-manufacture cycles.
- Programmable Logic: Configurable devices allowing user-defined logic setups; quick design adaptations using software; programming involves blowing electronic fuses.
Programmable Logic Devices (PLD)
- User-customizable integrated circuits (IC), offering advantages over standard ICs and ASICs.
- Contains programmable arrays of logic gates for various applications.
- Types include:
- PROM: Fixed AND array, programmable OR array.
- Programmable Logic Array (PLA): Both AND and OR arrays are programmable, allowing greater versatility.
- Programmable Array Logic (PAL): Specific arrangements enabling user configuration.
- Programming involves altering fusible links for output functions based on design requirements.
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Description
This quiz covers the key concepts of memory in digital systems as explored in Unit 5 of Digital Logic Design. It discusses the significance of memory, types of storage circuits, and their applications in processing information. Test your understanding of these fundamental principles.
