Microprogrammed Control Unit

Duration: 7 min

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Module outline

  1. About Course: UPPSC Course Overview
  2. Interview Preparation & Guidance: Interview Preparation
  3. Paper 1 | General Hindi: भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, वर्णमाला, समास, संधि, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material)
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  8. Paper 1 | Computer Organization and Architecture: Basics of COA, Programming the Basic Computer, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design
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  16. Paper 2 | Artificial Intelligence & High Performance Computing: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Natural Language Processing, Emerging Tech Trends
  17. Paper 2 | Image Processing: Digital Image Fundamentals, Image Enhancement, Image Restoration, Color Image Processing, Image Compression
  18. Paper 2 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  19. Paper 2 | Computer Graphics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing
  20. Paper 2 | Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, Java
  21. Paper 2 | Soft Computing: Fuzzy Sets, Artificial Neural Networks, Genetic Algorithms
  22. Paper 2 | Distributed System: Distributed Systems
  23. UPPSC Live Class Recordings: UPPSC Polytechnic Lecturer 2025 (CS)
  24. Previous Year Papers:
  25. Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a comprehensive lecture on Micro-Programmed Control Units, beginning with their historical introduction by Maurice Wilkes in 1951. The instructor explains that microprogramming serves as an intermediate level to execute computer program instructions, organizing outputs as sequences of microinstructions stored in special control memory. The lecture then transitions to a detailed comparison of Horizontal and Vertical micro-programming. Horizontal micro-programming is described as offering a higher degree of parallelism suitable for multi-processor systems, utilizing a control word where each bit directly corresponds to a control signal. Conversely, Vertical micro-programming is presented as a method that reduces control word size through encoding, though it limits parallelism to a maximum of one due to the decoder mechanism. The session concludes by noting that combinational units combining these approaches are preferred in most applications.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The lecture begins with a slide titled 'Micro-Programmed Control Unit'. The instructor introduces the concept, highlighting that the idea was introduced by Maurice Wilkes in 1951 as an intermediate level to execute computer program instructions. He underlines key phrases on the slide, including 'Maurice Wilkes', '1951', 'intermediate level', and 'microinstructions'. The text explains that microprograms are organized as a sequence of microinstructions stored in special control memory. The instructor emphasizes the main advantage: the simplicity of the structure, noting that outputs are organized in microinstructions and can be easily replaced. He further explains that binary patterns of control signals are stored in control memory, and hardware is used to generate the control signals after accessing a word from the memory.

  2. 2:00 – 5:00 02:00-05:00

    The topic shifts to 'Horizontal micro-Program'. The slide states that horizontal micro-programming provides a higher degree of parallelism and is suitable for multi-processor systems. A critical point highlighted is that it requires more bits for the control word, specifically '1 bit for every control signal'. The instructor draws a diagram illustrating this architecture. He sketches a control memory grid where rows represent microinstructions. He shows a Control Data Register (CDR) holding the control word, which is then fed into logic gates (AND gates) to generate specific control signals like ALU operations, register transfers, and memory control. The diagram visually demonstrates the direct mapping where a single '1' in the control word activates a specific hardware component without decoding.

  3. 5:00 – 7:08 05:00-07:08

    The lecture moves to 'Vertical Micro-program'. The slide explains that this method reduces the size of control words by encoding control signal patterns before storage. It offers more flexibility than horizontal micro-programming but has a maximum degree of parallelism of 1 due to the decoder. The instructor draws a diagram showing a 3x8 decoder. He illustrates how a 3-bit encoded input (e.g., 001, 010) selects one of the 8 output lines, which then activates a specific control signal. This contrasts with the horizontal approach. Finally, a 'Conclusion' slide appears, stating that the combinational Horizontal micro-Program and Vertical Micro-program controlled unit is preferred in most applications. The instructor underlines 'Horizontal micro-Program', 'Vertical Micro-program', and 'most application' to reinforce the final takeaway.

The video systematically builds an understanding of control unit design, starting from the foundational concept of microprogramming introduced in 1951. It effectively contrasts two primary implementation strategies: Horizontal and Vertical micro-programming. The horizontal approach prioritizes speed and parallelism by dedicating bits directly to signals, resulting in wider control words. In contrast, the vertical approach prioritizes compactness by encoding signals, which necessitates decoding and limits parallel execution. The synthesis of these concepts leads to the conclusion that modern systems often utilize a combinational approach, leveraging the benefits of both methods to optimize performance and flexibility in computer architecture.

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