Computer Architecture

About

The goal of the course is to introduce basic elements of computer organization and processor design so that students (as future professionals) do not treat computer as a black box that, in some magic way, executes programs. To this end, the course focuses on two key components of a computer – the processor and the memory subsystem. Specifically, the course covers the functional blocks and components that make up the processor and the memory hierarchy, their behavior and interaction, and their influence on the performance of a modern computer. Understanding these principles is a prerequisite for attaining a sufficient level of mechanical sympathy which helps in creating efficient programs even when using modern high-level programming languages.

Topics covered

• Computer performance, fundamental metrics and their limitations, comparing performance of computer architectures.
• Introduction to digital systems, logical expressions, boolean functions, gates, combinatorial and sequential circuits, basic building blocks, arithmetic operations.
• Instruction set architecture (ISA) implementation, single-cycle and multi-cycle data path and control, hard-wired and microprogrammed controller implementation, exception handling.
• Pipelined instruction execution, scalar pipelined data path, hazard detection and handling, branch prediction, exception handling.
• Superscalar architectures, static and dynamic instruction scheduling, out-of-order execution, speculative execution, contemporary architectures.
• Memory subsystem organization, latency and throughput, static and dynamic memory technology, cache organization and mapping, cache coherency.
• Brief overview of parallel processing and multiprocessor systems, Flynn’s taxonomy, Amdahl’s law, SIMD processing in multimedia, multi-core CPUs, GPUs.

Textbook

The course is based on the classic textbook by D. A. Patterson and J. L. Hennessy: Computer Organization and Design (5th edition, Morgan Kaufmann, 2013, ISBN 978-0124077263. 4th or 3rd edition also suffices). Students are assumed to be comfortable with the material in the introductory chapters (number representation, computer arithmetics, instructions of a computer) and the course focuses primarily on chapters dedicated to processor and the memory hierarchy.

Supplementary material

The following slides cover introductory material related to binary and hexadecimal numbers, logical operations, representations of numbers, storage of data in memory, storage of structure types, alignment, and the relation between pointers and memory addresses.

This material is not covered in this course — students should be familiar with the material from the Principles of Computers and Computer Systems courses.

• Numbers and operations
• Data representation and memory
• Variables, records, and pointers

Contact and office hours

If you have any question or comment, do not hesitate to contact me at bulej at d3s.mff.cuni.cz. E-mail is preferred for brief inquiries and it is generally OK to come to my office without an appointment. Please check my teaching schedule to avoid coming just before my lectures.

Do keep in mind that a consultation is not a private lecture, therefore if you need to discuss a topic at length, it is better to arrange an appointment with a clear goal. This is especially important if you have trouble understanding something, because the first step is to find out what is it that you still understand and what is the next bit which is unclear.

Final exam

The final exam is closed-book and written-only, and consists of a set of questions/exercises covering the course topics. On average, there are 12-13 questions with a total of 20 points. 10 points (50%) are required to get the grade 3, which is the lowest passing grade, 13 points (65%) are needed to pass with grade 2, and 17 points (85%) are required to pass with grade 1. Please note that if you need these grades converted to an american grading system, the local grade 3 will end up as american grade D, for which you might not get credit.

When grading the exam, I try to point out deficiencies which influenced the points awarded. Sometimes a particular answer is awarded a range of points. The lower bound corresponds to the amount that would be awarded if I were grading the exam in a very strict manner, while the upper bound corresponds to a very benevolent grading. A large difference between the lower and upper bounds in the total indicates that many answers were too ambiguous. To determine the exam outcome, I usually take the total from the middle of the range (never below middle). You will be provided with a scanned copy of your graded exam answer sheet.

The exam covers the following topics:

• fundamentals of computer performance (relation between execution time and clock cycles, instructions, and clock rate, Amdahl’s law),
• instruction set architecture (what kind of instructions do we need and why, compilation of basic elements of structured programming, i.e., assignments, conditionals, loops, function calls, argument passing),
• fundamentals of digital circuits (basic gates, concept of sequential and combinational circuits, datapath building blocks such as adders, ALUs, multiplexors, decoders),
• processor implementation (single-cycle and multi-cycle datapath and control),
• performance improvement techniques (pipelining datapath and control, pipeline hazards, forwarding/bypassing, branch prediction, handling of exceptions, static and dynamic multiple-issues pipelines and related techniques, such as out-of-order execution, speculation, register renaming), and
• memory hierarchy (caches, operation of write-through and write-back caches, cache miss model, cache architectures and their impact on cache misses, cache coherency, coherency protocols such as IV, MSI and MESI, false sharing).

The goal of the exam is to test understanding, not the ability to learn facts by heart. In many cases, factual information or diagrams are provided as part of the question. The required level of understanding roughly corresponds to the level of detail presented in the lectures and lecture slides. Going though relevant exercises in the H&P book is highly recommended.

To subscribe to an exam, use the Study Information System of the faculty.