IO Versus Memory Bus - IO Organization - Computer Organization and Architecture | Summary and Q&A

TL;DR

Designing a bus system for transfers between various locations in a computer system, such as registers, main memory, and peripheral devices, presents several challenges.

Key Insights

• 👨‍💼 Designing a bus system for transfers in a computer system involves distinguishing between various locations, such as registers, main memory, and peripheral devices.
• ❓ Internal transfers occur between the CPU and main memory, while external transfers involve peripheral devices.
• 👌 The distinct I/O approach involves using two separate bus systems and processors for memory and I/O transfers.
• 😃 Instructions are categorized as memory/reference instructions, register/reference instructions, or I/O instructions.
• 🍵 The main processor handles CPU-memory transfers, while an I/O processor handles I/O transfers.
• 👨‍💼 Careful design of the bus system is necessary to ensure efficient and accurate transfers between different locations.
• 👨‍💻 Programmers need to distinguish between these types of instructions when writing code.

Transcript

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Questions & Answers

Q: What are the challenges faced by designers when designing a bus system?

Designers face challenges in distinguishing between the various locations involved in transfers, such as registers, main memory, and peripheral devices. They must carefully design the bus system to differentiate between internal and external transfers.

Q: How are internal transfers different from external transfers?

Internal transfers occur between the CPU and main memory, while external transfers involve peripheral devices. Distinguishing between these types of transfers is crucial in designing a bus system.

Q: What is the "distinct I/O" approach in bus system design?

The distinct I/O approach involves using two separate bus systems - one for memory and one for I/O devices. This requires the use of two processors: the main processor for CPU-memory transfers and an I/O processor for I/O transfers.

Q: What are the categories of instructions involved in transfers?

Instructions are classified into three categories: memory reference instructions, register reference instructions, and I/O instructions. Memory and register reference instructions involve transfers between CPU and memory/registers, while I/O instructions involve transfers between CPU and peripheral devices.

Summary & Key Takeaways

• Designing a bus system requires careful consideration of the locations involved in transfers, such as registers, main memory, and peripheral devices.

• Distinguishing between internal transfers (between CPU and main memory) and external transfers (between peripheral devices and main memory/CPU) is crucial.

• One approach is to use two separate bus systems - one for memory and one for I/O devices, requiring the use of two processors.