Early and 3rd-4th Generation Computers

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Questions and Answers

What is the first step in the process of binary division?

Bring down the next digit of the dividend.

Perform a series of additions.

Record the final quotient.

Start from the left of the dividend. (correct)

In binary division, what do you put in the quotient if the subtraction of the divisor from the remainder is not possible?

A 0 (correct)

The divisor

The dividend

A 1

Why do most computers use the additive method for performing multiplication and division?

It simplifies the internal circuit design. (correct)

It reduces overall computation time.

It increases the accuracy of results.

It is easier to understand.

What is the primary action performed in the rules for additive method of division?

Subtracting the divisor repeatedly from the dividend. Signup and view all the answers

During binary division, when should you bring down the next digit of the dividend?

When subtraction is possible. Signup and view all the answers

What is a primary benefit of the integrated circuit technology in computers?

Reduces the size and cost of computers Signup and view all the answers

Which feature isNOT associated with fourth generation computers?

Reliance on magnetic core memory Signup and view all the answers

What year did Intel create the first microprocessor?

1971 Signup and view all the answers

Which of the following is a characteristic of fifth generation computers?

Inclusion of intelligent systems and robotics Signup and view all the answers

What was a major effect of integrated circuits on the computer industry?

Created a separation of hardware and software markets Signup and view all the answers

Which computer model was introduced during the fourth generation?

Apple Macintosh Signup and view all the answers

What does the instruction set architecture (ISA) provide?

An interface for programming the hardware Signup and view all the answers

Which of the following represents an advantage gained from microprocessors?

Increase in speed and storage capacity Signup and view all the answers

What does microarchitecture refer to?

The hardware implementation of the instruction set architecture Signup and view all the answers

What describes the transition from third to fourth generation computers?

Advancements leading to microprocessors and smaller form factors Signup and view all the answers

What characteristic of CISC architectures is highlighted?

They have a larger set of instructions with multiple addressing modes. Signup and view all the answers

Which of the following is NOT one of the operation types in the instruction set?

Data storage Signup and view all the answers

What defines the reliability criterion in computer metrics?

An increase in metric value indicates an increase in computer speed. Signup and view all the answers

What does the 'repeatability' criterion indicate?

A metric should yield consistent results under the same conditions. Signup and view all the answers

Which instruction type is associated with operations like 'add' and 'multiply'?

Arithmetic and logical Signup and view all the answers

In relation to ALU instructions, what is a distinguishing feature of memory-memory (2,2) or (3,3)?

They are considered the hardest pipelining implementation. Signup and view all the answers

What is the main focus of RISC architectures?

To reduce the number of instructions and addressing modes. Signup and view all the answers

Which of the following is a criterion related to the consistency of a metric?

Metrics should be precisely defined and universally applicable. Signup and view all the answers

What is the primary function of cache memory in relation to the CPU?

To provide faster access to frequently used data Signup and view all the answers

Which of the following statements about L1 cache is true?

L1 cache is accessed first by the CPU Signup and view all the answers

What role does the key register (K) have in associative memory?

It specifies which parts of the argument word to compare Signup and view all the answers

What kind of devices qualify as auxiliary memory devices?

Memory Card Reader Signup and view all the answers

What is a key characteristic of L2 cache compared to L1 cache?

L2 cache is accessed if data is not found in L1 cache Signup and view all the answers

Which cache level is known as the primary cache?

L1 Cache Signup and view all the answers

What does the associative memory array do?

Contains words to be compared against the argument word Signup and view all the answers

Which of the following is true about cache memory?

It constantly replaces old data with newer data Signup and view all the answers

What is the first step the processor takes when encountering an I/O operation during program execution?

It sends a read or write command to the I/O module. Signup and view all the answers

Which of the following best describes the nature of interrupt-driven I/O?

It allows the CPU to perform other tasks while waiting for I/O. Signup and view all the answers

What role does the I/O status register play in I/O operations?

It indicates whether the I/O operation is complete. Signup and view all the answers

What is a major advantage of interrupt-driven I/O?

It guarantees no CPU cycles are wasted during idle I/O waits. Signup and view all the answers

In what situation would a peripheral device send an interrupt to the CPU?

When it has new data ready for the system. Signup and view all the answers

Which option describes a potential disadvantage of using interrupt-driven I/O?

It can introduce complexity in low-level programming. Signup and view all the answers

What sequence accurately represents the basic operations of interrupt-driven I/O?

CPU issues read command, I/O module interrupts CPU, I/O module transfers data. Signup and view all the answers

What is one of the main problems associated with interrupt-driven I/O?

Determining which device caused the interrupt. Signup and view all the answers

Study Notes

Early Computer Models

The CDC 7600 and B2500 were introduced alongside the IBM 360.
These models were used for business and scientific programs.
The IBM 360 was manufactured in 1961 in Silicon Valley.

3rd Generation Computers (1964-1971)

Integrated Circuit (IC) technology was a defining feature of this generation.
ICs reduced the size and cost of computers.
Advantages of ICs:
- Reliable, compact, and cheaper.
- Hardware and software were sold separately, which gave rise to the software industry.
- The customer service industry flourished due to the increased computing power.
- Computers became more sophisticated, able to run multiple programs at the same time.
- Allowed for sharing computer resources, supporting interactive processing.

4th Generation Computers (1971-Present)

The development of the fourth generation spanned 55 years.
Key hardware inventions were silicon chips, microprocessors, and advanced storage devices.
Notable computer models during this time:
- Apple Macintosh, Dell, IBM, Acer.
In 1971 Intel created the first microprocessor, and Steve Jobs built the first Apple computer.
In 1981, IBM released its first personal computer.

Microprocessor Revolution

A specialized chip developed to handle computer memory and logic.
It's a large-scale integrated circuit with thousands of transistors capable of performing CPU functions.
Advantages of Microprocessors:
- Computers became 100 times smaller than ENIAC.
- Significant gains in speed, reliability, and storage capacity.
- The personal and software industries experienced rapid growth.

5th Generation Computers (Present and Beyond)

Characterized by advanced and developing technologies for enhanced efficiency.
Includes programs for translating languages.
Key features:
- Silicon Chips
- Processors
- Robotics
- Virtual Reality
- Intelligent Systems

New Era Computers

Represents a more advanced, sophisticated, and modern era in computing.
Latest inventions:
- Supercomputers
- Mainframe Computers
- Minicomputers
- Personal Computers
- Mobile Computers

Instruction Set Architecture (ISA)

A standardized interface between software and hardware.
Defines:
- A set of instructions with their argument fields, assembly syntax, and machine encoding.
- Named storage locations (registers and memory).
- Addressing modes.
Acts as a bridge between software and hardware.
Represents the entire set of commands a processor can execute to run program instructions.

Intel 8085 ISA

Contains 246 operation codes and 74 instructions.

Microarchitecture

The hardware implementation of the ISA.
Defines the hardware circuitry of the processor chip that supports a specific ISA.

Program Compilation Process

Memory-Memory (2,2) or (3,3):
- ALU instruction: 2/3 memory, 2/3 operands.
- Hardest pipelining, most compact program.
- Not used today (DEC VAXX).

Types of Instruction Set Operations

Operator Type | Examples ------------------|----------------------------------------------------------------
Arithmetic and logical | Integer arithmetic and logical operations: add, or
Data transfer | Load-stores (move on machines with memory addressing)
Control | Branch, jump, procedure call, and return, traps
System | OS call, virtual memory management instructions
Floating point | Floating point operations: add, multiply
Decimal | Decimal add, decimal multiply, decimal to character conversion
String | String move, string compare, string search
Graphics | Pixel operations, compression/decompression operations

CISC vs. RISC

CISC (Complex Instruction Set Computer) uses a large set of instructions with many addressing modes.
RISC (Reduced Instruction Set Computer) uses a smaller set of instructions with fewer addressing modes.

Computer Metrics

Criteria for Valid Metrics (David Lilja)
- Linearity: An increase in the performance of a computer by a fraction x should be reflected by an increase of fraction x in the metric.
- Reliability: Should accurately indicate whether one computer is faster than another.
- Repeatability: Should consistently yield the same result under same conditions.
- Ease of Measurement: Should be easily measured to allow independent verification.
- Consistency: Should be precisely defined and applicable across different systems.

Binary Arithmetic

Subtraction using Complementary Method: A common method for binary subtraction.
Multiplication: Multiplication in binary is performed using a process similar to decimal multiplication.
Division: Binary division involves repeatedly subtracting the divisor from the dividend.
- Rules for Binary Division:
  - Start from the left of the dividend.
  - Perform subtractions where the divisor is subtracted from the dividend.
  - If subtraction is possible, put a 1 in the quotient and subtract the divisor.
  - If not possible, record a 0 in the quotient.
  - Bring down the next digit to add to the remainder.
  - Proceed by repeating the process.

Additive Method of Multiplication and Division

Most computers use additive methods for multiplication and division, simplifying the internal circuit design.

Auxiliary Memory

Also known as backing storage or secondary storage.
It stores the majority of information.

Auxiliary Memory Devices

Memory Card Reader
USB Flash Memory
Media Devices
External Optical Drive

Cache Memory

Stores frequently accessed data from the main memory, enabling faster access.
The CPU checks cache memory first, then main memory if data is not found in cache.
It transfers blocks of recent data into the cache, replacing older data to accommodate new data.

Cache Memory Levels

L1 Cache (2kb-64kb)
- Known as primary cache or level 1 cache.
- The fastest cache.
- Smaller size and shorter access delay.
L2 Cache (256kb-512kb)
- Next level in the hierarchy.
- Accessed if the data is not found In L1.
- Typically implemented using DRAM.
L3 Cache (1mb-8mb)
- The largest and slowest cache, but still faster than RAM.

Associative Memory (CAM)

Allows data retrieval based on content rather than address.
Matches a given input with stored patterns or data.
Organization:
- Argument Register (A): Contains the word to be searched.
- Key Register (K): Specifies the part of the argument word to be compared.
- Associative Memory Array: Contains the words to be compared.
- Match Register (M): Indicates which words match the argument word.

Programmed I/O

Programs executed by the processor to control I/O operations:
- Sensing device status
- Sending a read or write command
- Transferring data
Operation:
1. Processor encounters I/O instruction.
2. Processor issues command to relevant I/O module.
3. I/O module performs the action and updates the I/O status register.
4. Processor checks the I/O module until the operation completes.

Interrupt-Driven I/O

Peripheral device signals the need for data transfer, interrupting the processor.
Processor enters an interrupt service routine to handle the request, taking into account interrupt levels and priorities.

Interrupt Drivers I/O: Input

Device interrupts the CPU when new data is ready to be retrieved.
The actions depend on whether the device uses I/O ports or memory mapping.

Interrupt Drivers I/O: Output

Device interrupts the CPU when it's ready to accept new data or acknowledge successful data transfer.

Basic Operations of Interrupt

CPU issues a read command.
I/O module gets data while CPU works on other tasks.
I/O module interrupts CPU, which requests data.
I/O module transfers data.

Interrupt I/O Advantages and Disadvantages

Advantages:*
Fast
Efficient
Disadvantages:*
Complex to write in low-level languages.
Difficult to integrate different components.
Often handled by hardware manufacturer or OS maker (e.g., Microsoft)

Problems with Interrupt I/O

Multiple I/O modules: How to determine which device issued the interrupt?

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Description

Explore the evolution of early computer models, focusing on the CDC 7600, B2500, and IBM 360. Learn about the advancements brought by integrated circuits in the 3rd generation and the innovative hardware developments in the 4th generation of computers that shaped modern computing.