CH05 zoom

Week 6 Overview

• Chapter 5 focuses on instruction sets and architectures.

• Midterm exam review will be included in the lecture.

• New classroom: Science and Education Center, Room 115, due to size considerations.

• The midterm exam is mandatory and must be taken in person.

Midterm Exam Details

• Date: Next week, after the lecture during the first half of class.

• Students must inform the instructor if there are issues attending in person to arrange alternatives.

• Bring a fully charged laptop for the exam on D2L.

• Allowed: up to 10 pages of single-sided notes and the textbook (including e-text). Open book exam.

Homework Review

• Micro Program Operation vs. Assembly Language:

  • Regular assembly language requires multiple execution steps; micro program instructions directly control control signals for operations.

• CISC vs. RISC Architecture:

  • CISC: Variable-length instructions allowing complexity; harder to decode.

  • RISC: Fixed-length instructions, simpler decoding, and execution; all instructions are the same length.

Programming Examples

• Summing integers using code provided: Initialize X at 1, sum until 10, increment X, and check conditions for the loop.

• Discussed return address handling in subroutines: stacks for recursion management since a single register can't accommodate multiple calls efficiently.

• C Program Example:

  • Functions Find Max and Count Odd: both take an integer array and size, processing to calculate result based on conditions.

• Stack implementation for arrays and memory allocation in C discussed thoroughly, including linked lists.

Instruction Sets Overview

• Factors in instruction set design: bits per instruction, operand locations, types, and size.

• Endianness:

  • Little-endian stores least significant byte first; big-endian stores most significant byte first, affects multi-byte integer storage.

• Memory addressing: stack vs. accumulator vs. general-purpose registers.

Architecture Types

• Types of CPU architectures: stack architecture (operands implicitly taken from stack), accumulator architecture (only one operational accumulator), and general-purpose register architecture (multiple registers).

• CISC generally leads to longer instruction lengths compared to RISC, which optimizes for fixed lengths.

• Memory-to-memory, register-memory, and load-store architectures affect instruction sizes and execution.

Pipelining and Hazards

• Instruction pipelining enhances throughput by breaking the fetch-decode-execute cycle into stages, allowing parallel execution.

• Hazards may arise during this process due to resource conflicts, data dependencies, or conditional branch instructions that stall the pipeline.

• Compilers must optimize instruction order to minimize stalls and maximize throughput.

C Programming and Memory Management

• Importance of manual memory management in C using malloc and free: responsible for allocating and deallocating memory, unlike Java's garbage collection.

• Example of building and cleaning up a linked list in C demonstrated.

• Debugging using gdb highlighted: setting breakpoints, viewing memory contents, and stepping through code execution.

Review of Important Concepts

• Memory hierarchy: registers, caches (L1, L2), RAM, and permanent storage.

• Numeric conversion between decimal, binary, hex, ASCII, and Unicode.

• Handling floating point representation, including IEEE standards.

• Pipeline strategies, addressing modes, and RISC vs. CISC architectures enumerated.

• Key distinctions and inter-relationships between hardware designs and software implementations.

Recommended Preparation Strategies

• Thorough review of memory management and programming concepts in C before the exam.

• Practice problems covering endian conversions, numeric systems, and instruction sets.

• Prepare notes focusing on key differences between RISC and CISC architectures for the exam.