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Questions and Answers
What is the advantage of DRAM memory?
What is the advantage of DRAM memory?
What is the disadvantage of DRAM memory?
What is the disadvantage of DRAM memory?
How many address lines are used in Direct I/O method to identify an I/O device?
How many address lines are used in Direct I/O method to identify an I/O device?
What is the difference between I/O Read and I/O Write control signals?
What is the difference between I/O Read and I/O Write control signals?
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How does the MPU communicate with an I/O device in Memory-Mapped I/O method?
How does the MPU communicate with an I/O device in Memory-Mapped I/O method?
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What is the type of memory that stores data in the form of charge in capacitors?
What is the type of memory that stores data in the form of charge in capacitors?
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Which of the following statements is true about Direct I/O method?
Which of the following statements is true about Direct I/O method?
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What is the main difference between Direct I/O and Memory-Mapped I/O methods?
What is the main difference between Direct I/O and Memory-Mapped I/O methods?
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How many input devices and output devices can be identified by the MPU in Direct I/O method?
How many input devices and output devices can be identified by the MPU in Direct I/O method?
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What is the main disadvantage of using DRAM memory?
What is the main disadvantage of using DRAM memory?
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Study Notes
Memory Types
- ROM (Read Only Memory): data can only be read, no writing is allowed; used to store permanent programs; nonvolatile type of memory
- EPROM (Erasable Programmable Read Only Memory): programmable by user, information can be erased by exposing to ultraviolet light, and reprogrammed using EPROM programmer; disadvantage: all data gets erased even if only one bit needs to be changed
- EEPROM (Electrically Erasable Programmable Read Only Memory): similar to EPROM, but erasing is done by electrical signals; advantage: memory location can be selectively erased and reprogrammed; disadvantage: manufacturing process is complex and expensive
- R/W Memory (Read/Write Memory): also called RAM, allows reading and writing data, volatile type of memory; used to check execution of programs
R/W Memory Subtypes
- SRAM (Static RAM): consists of flip-flops, bit status remains until next write operation or power supply is switched off; advantages: fast access time, no refreshing required; disadvantages: low package density, expensive
- DRAM (Dynamic RAM): stores data in capacitors, requires refreshing to maintain charge, high package density, low cost; disadvantage: requires refreshing circuit every few milliseconds
Microprocessor Clock
- Also called clock rate, measures speed at which microprocessor executes instructions
- Measured in megahertz (MHz) or gigahertz (GHz)
- CPU requires a fixed number of clock ticks to execute each instruction
- Faster clock speed means more instructions can be executed per second
Classification of Memory
- ROM (Read Only Memory): data can only be read, no writing allowed; used to store permanent programs; nonvolatile
- Masked ROM: program or data permanently installed at time of manufacturing; cannot be altered; expensive but economic for large quantities
- PROM (Programmable Read Only Memory): similar to masked ROM, but has fuse links; can be programmed, but disadvantage: no chance of re-growing fuse, and programmed data can be altered due to aging
I/O Devices and Interfacing
- MPU communicates with outside world through I/O devices
- Two methods of I/O device identification and communication: Direct I/O (Peripheral) and Memory-Mapped I/O
- Direct I/O uses two instructions (IN & OUT) for data transfer, MPU uses 8 address lines to send I/O device address, and can differentiate between input and output devices using control signals IOR and IOW
- Memory-Mapped I/O uses 16 address lines to identify I/O device, similar to communicating with memory location
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Description
This quiz covers the basics of Read Only Memory (ROM) and Erasable Programmable Read Only Memory (EPROM) in microprocessor architecture.
