Computer Architecture and Organization

Computer Architecture vs. Computer Organization

• Computer Architecture: Attributes visible to the programmer and impact the logical program execution.
• These attributes include instruction set, number of bits for data types, I/O mechanisms, and addressing memory techniques.
• Computer Organization: Hardware details transparent to the programmer like control signals and interfaces.
• This includes operational units and their interconnections that realize the architectural specifications.

IBM System/370 Architecture

• Introduced in 1970, it comprised several models.
• Allowed upgrades to faster models without abandoning existing software.
• New models used improved tech while maintaining the same architecture.
• Customer's software investment was thereby protected.
• Its architecture is still used in IBM's mainframe product line.

Structure and Function

• Structure: The way components relate to each other.
• Function: The operation of individual components as part of the structure.
• Complex systems have a hierarchical nature essential to their design and description.
• Designers need only focus on one level of the system structure and function at a time.

Computer Functions

• Data processing which may take a wide variety of forms with broad processing requirments
• Data storage that is short-term and long-term
• Data movement with input-output (I/O) of data via peripherals connected directly to the computer or data communications of data moved to or from a remote device over longer distances
• Control unit manages a computer's resources and directs functional parts based on instructions.

Structural Components of a Computer

• CPU (Central Processing Unit): It controls the computer's operation and processes data.
• Main Memory: Stores the data.
• I/O (Input/Output): Moves data between the computer and its external environment.
• System Interconnection: Mechanism for communication among the CPU, main memory, and I/O.

CPU Components

• Control Unit: Directs CPU operations and thus the computer.
• Arithmetic and Logic Unit (ALU): Computer's data processing unit.
• Registers: Provide internal CPU storage.
• CPU Interconnection: Facilitates communication among the control unit, ALU, and registers.

Multicore Computer Structure

• CPU: Computer portion that fetches and executes instructions, with an ALU, control unit, and registers.
• In a single-processing unit system, it is referred to as a processor.
• Core: An individual processing unit on a processor chip, that may be equivalent in functionality to a CPU on a single-CPU system.
• Specialized processing units are also referred to as cores
• Processor: A silicon chip containing one or more cores that interprets and executes instructions.
• A multicore processor contains multiple cores.

Cache Memory

• Multiple memory layers existing between the processor and main memory.
• Smaller and faster than main memory.
• It speeds up memory access by storing data likely to be used soon from main memory.
• Performance improves with multiple cache levels, with level 1 (L1) closest to the core. Additional levels (L2, L3, etc.) are progressively farther.

History of Computers - First Generation

• Vacuum tubes were used for digital logic elements and memory.
• IAS computer used a stored program concept approach, and is attributed to mathematician John von Neumann
• This concept was first published in 1945 for the EDVAC.
• Design of the IAS began at the Princeton Institute for Advanced Studies.
• The IAS computer was completed in 1952.
• It Became the prototype for subsequent general-purpose computers.

IAS Computer Registers:

• Memory Buffer Register (MBR): Contains a word to be stored in memory or sent to the I/O unit and receives a word from memory or from the I/O unit.
• Memory Address Register (MAR): Specifies the memory address for reading from or writing to the MBR.
• Instruction Register (IR): Contains the 8-bit opcode instruction being executed.
  • Instruction Buffer Register (IBR): Temporarily holds the right-hand instruction from a word in memory.
• Program Counter (PC): Has the address of the next instruction pair to be fetched from memory.
• Accumulator (AC) and Multiplier Quotient (MQ): Temporarily hold operands and results of ALU operations.

Integrated Circuits

• Data storage is provided by memory cells.
• Data processing is done by gates.
• The paths among components move data from memory to memory and through gates.
• Control is applied as paths among components carry control signals.
• A computer contains gates, memory cells, and interconnections among these elements.
• Gates and memory cells are constructed from basic digital electronic components.
• Transistors, resistors, and conductors can be made from semiconductors such as silicon.
• Many transistors can be produced at the same time on a single wafer of silicon.
• Transistors can be connected with a processor metallization to form circuits.

Transistors

• They are fundamental building blocks of digital circuits used to construct processors, memories and other digital logic devices
• The active part of the transistor is made of silicon or some other semiconductor material that can change its electrical state when pulsed
• In its normal state the material may be nonconductive or conductive
• The transistor changes its state when voltage is applied to the gate
• Discrete Component : A single, self-contained transistor, that Were manufactured separately, packaged in their own containers, and soldered or wired together onto Masonite-like circuit boards

Moore's Law

• In 1965, Gordon Moore (Intel co-founder) observed that the number of transistors on chips was doubling every year.
• The doubling rate slowed to every 18 months in the 1970s, but has remained at that rate since.

Consequences of Moore's Law:

• Cost of computer logic and memory circuitry has decreased dramatically.
• Electrical path length is shortened, increasing operating speed.
• Computers become smaller and easier to use.
• Power and cooling requirements are lessened.
• There are fewer interchip connections

The Intel Microprocessor Evolution

• The 4004, introduced in 1971, had 2300 transistors, 108 kHz clock speed, and 640 bytes addressable memory
• The 486TM SX, introduced in 1991, had 1.185 million transistors, 16-33 MHz clock speed, 4 GB addressable memory, and 8 kB cache The Pentium 4, introduced in 2000, had 42 million transistors, 1.3-1.8 GHz clock speed, 64 GB addressable memory, 64 TB virtual memory, and 256 kB L2 cache.

Highlights of the intel product line Evolution:

• The 80386, an Intel first 32-bit Machine, was the first Intel processor to support multitasking.
• The Pentium Architecture introduced the use of superscalar Techniques for multiple instructions to execute in parallel
• Intel incorporated MMX technology, designed specifically to process video, audio and graphic data efficiently, into The Pentium II
• The Core architecture extends to 64 bits while more recent Core offerings have as many as 10 cores per chip

Embedded Systems

• The systems use electronics and software within other products.
• Billions of such systems are produced annually.
• Use electric power and are tightly coupled to their environment.
• There can be real-time constraints in the need to interact with the environment.
• Timing of software operations are dictated by the requirements of motion speed, measure precision, and time durations.
• Managing multiple activities puts more complex real-time constraints.

The Internet of Things (IoT)

• Refers to the expanding interconnection of smart devices, ranging from appliances to tiny sensors.
• Primarily driven by deeply embedded devices.
• Consists of various generations of deployment, including IT with PCs, servers, and routers using wired connectivity, operational Technology (OT), and Personal Technology
• Sensor/actuator technology is bought by consumers, as part of larger systems using a form of wireless connectivity.
• It is the fourth generation that is usually thought of as the and it is marked by the use of billions of embedded devices.

Embedded Operating Systems Approaches:

• Adapt an existing OS for the embedded application
• Design and implement an OS solely for embedded use

Application vs Dedicated Processors

• Application processors: This type of processors Is defined by the processors ability to execute complex operating systems and are general purpose in nature. such as the smartphone with wide variety of functions
• Dedicated Processors: These processors are dedicated to one of a small number of specific task and can be engineered to reduce size and cost

Deeply Embedded Systems

• They are a subset of embedded systems with processor behavior difficult to observe by programmer and user.
• Use a microcontroller instead of a microprocessor.
• These are not programmable once the program logic has been burned into ROM, and have no user interaction.
• These dedicated single-purpose devices, detect environment conditions, perform processing, and produce a response.
• They often have wireless capabilities and appear in configuration/networks deployed over a large area.
• They typically present with extreme resource constraints for size, memory, processing power, time and power consumption.

ARM

• ARM (Acorn RISC Machine/Advanced RISC Machine): Refers to a processor architecture evolving from RISC design, used in embedded systems.
• Family of RISC-based microprocessors and microcontrollers are designed by ARM Holdings in Cambridge, England.
• ARM chips are fast processors with small die size and low power needs.
• The architecture the most used embedded processor and the most used of any kind in the world.

Understand the difference between computer architecture, which is visible to the programmer, and computer organization, which deals with hardware details. Explore the IBM System/370 architecture and its impact. Learn about structure and function in computer systems.