Computer Organization Chapter 8: Input/Output

Computer Organization and Architecture

• The book is titled "Computer Organization and Architecture Designing for Performance" 11th Edition, Global Edition
• It is published by Pearson
• Copyright is © 2022 Pearson Education, Ltd.

Chapter 8: Input/Output

• I/O modules link external devices to the computer system.
• A generic I/O module interfaces with the system bus and peripheral devices.
• External devices can be categorized as human-readable (VDTs, printers) and machine-readable (magnetic disks, sensors).
• There are links to peripheral devices present in I/O module
• There are specific external devices such as video display terminals, printers, magnetic disk and tape systems, sensors, and actuators, that can be categorized as human readable.
• Key I/O functionalities include control and timing, processor communication and device communication.
• I/O operations can be handled using programmed I/O, interrupt-driven I/O, or DMA.
• A block diagram shows the internal components of an external device, including control logic, a buffer, and a transducer.
• Input/output commands involve control, test, read and write signals to the peripherals.
• Common I/O mechanisms (table) include programmed I/O, interrupts, and DMA.
• I/O instructions include commands, such as control, test, read, and write.
• Three common I/O techniques are programmed I/O, interrupt-driven I/O, and direct memory access (DMA).
• Memory-mapped I/O and isolated I/O are two different approaches to addressing I/O devices.
• Keyboard/monitor input/output uses the International Reference Alphabet (IRA) code.
• Devices are identified differently with multiple interrupt lines, software poll, daisy chain, or bus arbitration schemes.

Chapter 10: Number Systems

• The text defines the decimal system as a positional number system based on the digits 0-9.
• Decimal fractions utilize negative powers of 10 for fractional parts.
• The general form for these systems is (...a3a2a1a0.a_1a_2a_3...)r.
• A number in a positional number system has weights associated with each digit position, determined by the radix (or base) raised to the power of the position.
• The binary system, based on 0 and 1, uses powers of 2 to represent numbers.
• The hexadecimal system uses the sixteen symbols 0-9 and A-F to represent numbers.

Chapter 11: Computer Arithmetic

• An Arithmetic Logic Unit (ALU) performs arithmetic and logical operations on data.
• The ALU is the core computational component of a computer, receiving and sending data to it via operands and results.
• Integer representation methods include sign-magnitude, twos complement, and biased representation.
• Range extension methodologies apply to integer representation, extending the representable range by increasing the bit length.
• This is done by shifting the sign bit to the leftmost position and filling remaining bits with the sign bit.
• Fixed-point representation has a fixed position for the radix point.
• Floating-point representation uses a different representation for fractions to allow them to be represented in the system.
• IEEE 754 standards define different types of floating-point formats.
• Interval arithmetic can represent a range of values, useful for error control, by representing the result as a range of values, one lower and one upper bound.
• Truncation is a type of rounding toward zero
• Infinity is a concept used to deal with results of operations like division by zero, where the result is treated as a large value beyond the range of representable numbers.
• Overflow and underflow are conditions that may occur during arithmetic operations in twos complement and floating-point representations.
• A guard bit can be used to store bits when the precision of a result is limited by the size of a register.
• The IEEE standard for binary floating-point arithmetic handles cases like infinity and NaN (Not a Number).
• Other methods for performing operations such as multiplication, division, and exponentiation.

Chapter 13: Instruction Sets: Characteristics and Functions

• A machine instruction specifies the operation executed by the computer. The instruction set is the collection of all instructions executed by the processor.
• Instructions include opcodes, operands, and addresses. Operands are the data the instruction operates on, and can be in memory, registers, or immediate values.
• Instructions can include a sequence of operations.
• Various data types are present in computers for different purposes such as numbers, characters, and logical data.
• Processors use an instruction set.
• Data types include integers, packed decimal, Floating-Point, and decimal.
• A simple instruction is a sequence of bits corresponding to opcodes and operands.
• Different types of operations exist in instructions, including data transfer, arithmetic, logical, conversion, input/output, and transfer of control.
• Instruction set design involves various key issues: operation repertoire, data types, instruction format, registers, addressing.
• Examples of instructions and their operations provided in table format.