Digital and Hybrid Computers Overview

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Questions and Answers

Which computer is primarily designed for individual use and is often referred to as a personal computer?

Hybrid computer

Micro computer (correct)

Mini computer

Mainframe computer

What type of computer combines features of both analog and digital computers?

Mainframe computer

Hybrid computer (correct)

Micro computer

Super computer

What is a common feature of mainframe computers?

Processes data at a speed of 100 million instructions per second (correct)

Designed for individual use

Utilizes analog-to-digital converters

Supports several users simultaneously

Which of the following is a characteristic of minicomputers?

Support 10 to 100 users simultaneously Signup and view all the answers

What distinguishes hybrid computers from digital computers?

Hybrid computers require converters for both input and output. Signup and view all the answers

Which type of computer is considered the most powerful and can process tasks at high speeds?

Super computer Signup and view all the answers

What feature is NOT typically associated with micro computers?

Designed to be used by multiple users simultaneously Signup and view all the answers

Which statement best describes the evolution of mini computers?

They were developed to perform limited tasks and are less expensive than mainframes. Signup and view all the answers

What is the main purpose of Optical Character Recognition (OCR) software?

To convert bitmap images of characters to ASCII code. Signup and view all the answers

Which of the following is a disadvantage of OCR technology?

It requires standard size characters for proper scanning. Signup and view all the answers

Which font is commonly associated with MICR systems for cheque processing?

E13B Signup and view all the answers

What is a key advantage of using MICR technology?

It can accurately scan folded or roughly handled cheques. Signup and view all the answers

What technology does a Bar Code Reader predominantly use to recognize barcodes?

Laser-beam technology Signup and view all the answers

Which of the following describes how barcodes represent data?

Through vertical lines with varying widths and spaces. Signup and view all the answers

What character set do UPC barcodes typically represent?

Numbers 0-9 only Signup and view all the answers

What is a limitation of using MICR technology?

It requires specialized ink. Signup and view all the answers

What is the result of the subtraction 1010101 – 1001100 using the complement method?

0001000 Signup and view all the answers

What is the first step in performing subtraction using the binary complement method?

Find the complement of the number to be subtracted. Signup and view all the answers

How is the final result adjusted if there's no carry during binary subtraction?

The result is complemented and a negative sign is attached. Signup and view all the answers

What is the product of 1010 and 1001 in binary multiplication?

1011010 Signup and view all the answers

What does the binary multiplication of any number with 0 yield?

0 Signup and view all the answers

During binary division, what happens if the divisor cannot be subtracted from the dividend?

A 0 is placed in the quotient. Signup and view all the answers

What is the quotient of the operation 1 divided by 1 in binary?

1 Signup and view all the answers

What is the main principle of binary multiplication compared to decimal multiplication?

It uses the same multiplication tables. Signup and view all the answers

What does BCD stand for in computer coding?

Binary Coded Decimal Signup and view all the answers

How many characters can be represented in standard ASCII?

128 Signup and view all the answers

Why is BCD limited to 4 bits for representing decimal digits?

4 bits can represent only 16 characters Signup and view all the answers

Which of the following is NOT a coding scheme mentioned?

UTF-8 Signup and view all the answers

What is the purpose of the extra parity bit in ASCII?

For error-checking purposes Signup and view all the answers

What is the main limitation of 4-bit BCD coding?

Insufficient bits for character representation Signup and view all the answers

EBCDIC is primarily used by which type of systems?

IBM mainframe systems Signup and view all the answers

Which code allows for the representation of both letters and special symbols?

Both B and C Signup and view all the answers

How many distinct characters can be represented using 8 bits in EBCDIC?

256 Signup and view all the answers

What is the primary purpose of a parity bit in data transmission?

To detect errors in transmission Signup and view all the answers

Which encoding standard was developed to address the needs of multiple languages including Chinese and Japanese?

Unicode Signup and view all the answers

What is a key drawback of the Unicode system?

It has issues with storage space and transmission time Signup and view all the answers

In an odd parity system, what must be true about the total number of '1' bits transmitted?

It must be odd Signup and view all the answers

Which of the following statements about EBCDIC is correct?

It was developed by IBM for mainframes. Signup and view all the answers

Which method can be employed to convert characters between ASCII and EBCDIC?

Electronic circuits or computer programs Signup and view all the answers

What is a limitation of the parity check technique?

It fails when an even number of bits are incorrectly received. Signup and view all the answers

Study Notes

Digital Computers

Digital computers use digital technology to represent information numerically.
They represent data as discrete electrical pulses, either 'on' or 'off'.
This results in accurate output.
Most modern computers are based on digital technology.

Hybrid Computers

Hybrid computers combine the benefits of analog and digital computers.
They offer the speed of analog computers and the accuracy of digital computers.
They accept analog data but process it digitally.
They require analog-to-digital and digital-to-analog converters for input and output.

Computer Classification by Data Processing

Computers are categorized based on data processing capabilities into four types.
Microcomputers, Minicomputers, Mainframe computers, and Supercomputers.

Microcomputers

These computers use a microprocessor chip as the central processing unit.
They emerged in the 1970s.
The first microcomputers were built with 8-bit processors.
Known as personal computers, designed for individual use (PCs, workstations or notebooks).
They are relatively small, affordable and widely used.
Examples include IBM PC, IBM PC/XT, IBM PC/AT.

Minicomputers

They emerged in the 1960s.
They are smaller mainframes that perform limited tasks.
Less expensive than mainframes.
Less powerful in terms of processing capabilities compared to mainframes.
Capable of supporting 10 to 100 users simultaneously.
Early models used 8 or 12-bit processors.
Later progressed to 16 and 32-bit processors.
More powerful versions were developed known as supermini computers.
Examples: IBM AS400.

Mainframe Computers

They are very powerful computers designed to support thousands of users simultaneously.
They include powerful data processing systems.
They can run multiple operating systems.
They can process up to 100 million instructions per second.
They are large, expensive, with large storage capacities and high processing speeds.

Optical Character Recognition (OCR)

Used for converting images of characters to ASCII code.
It first creates a bitmap image of the document.
OCR software then translates the image into ASCII code, allowing computers to interpret letters, symbols or numbers.
The document must be typed using OCR fonts.
Common standards are OCR-A (American standard) and OCR-B (European standard).

OCR Advantages

Speedy data entry.
Accepts a wide range of fonts.

OCR Disadvantages

Expensive.
Scanning works correctly only if characters are standard size.
Dusty paper cannot be scanned properly.

Magnetic Ink Character Recognition (MICR)

MICR systems use special magnetizable ink to print characters that can be read by magnetic devices.
Common E13B font is used, containing numbers 0-9 and 4 symbols.
Character detection occurs in two steps.
First, the MICR Reader-Sorter reads the data on cheques and sorts them for further processing.
Magnetized characters are read by the head.

MICR Advantages

Speedy data entry.
Accurate output.
Folded or roughly handled cheques can be scanned accurately.

MICR Disadvantages

MICR software is required.
Limited fonts used, primarily in banking industries.

Barcode Reader Devices

Data is encoded using small lines known as barcodes.
Barcodes represent alphanumeric data by combinations of vertical lines varying in width and spacing.
Bar Code Readers are devices that recognize barcode data.
They scan barcode images, convert them to alphanumeric values, and feed them to computers.
They often use laser-beam technology.
The laser scans across the barcode pattern, sensed by a light-sensitive decoder.
The reflected light patterns are transformed into electrical pulses and then into alphanumeric values.
Various barcodes exist for different uses.
The most common is UPC (Universal Product Code), consisting of 10 digits, the first 5 identifying the manufacturer and the remaining 5 identifying a specific product.

Number Complement

Example of subtraction using a binary system.
Step 1: Find the complement of the number being subtracted.
Step 2: Add the complement to the original number.
Step 3: If a carry occurs, add 1 to the result.
If no carry occurs, complement the result (in binary) and add a negative sign.

Multiplication in Binary

Multiplication in binary follows the same rules as decimal multiplication.
Remember the following table:
- 0 x 0 = 0
- 0 x 1 = 0
- 1 x 0 = 0
- 1 x 1 = 1

Binary Division

The following table is used in binary division:
- 0 / 1 = 0
- 1 / 1 = 1
Steps:
- Begin from the left of the dividend.
- Perform subtraction where the divisor is subtracted from the dividend.
- If subtraction is possible, place a 1 in the quotient and subtract the divisor from the matching digits in the dividend; otherwise, place a 0 in the quotient.
- Bring down the next digit to the right of the remainder.
- Repeat step 2 until there are no more digits in the dividend.

Units of Information (Codes)

Most computers use coded versions of binary to represent characters and symbols.
This standardization enables data transfer between systems.
Codes include BCD, ASCII, EBCDIC, and Unicode.

BCD (Binary Coded Decimal)

One of the earliest computer codes.
Each decimal digit is converted to its binary equivalent (4 bits).
Convenient for conversion but limited in representing characters (only 16).
Extended to a 6-bit code for representing more characters.

ASCII (American Standard Code for Information Interchange)

Each character (letters, digits, symbols) is assigned a unique bit pattern.
The standard ASCII character set uses 7 bits, representing 128 characters.
It utilizes one extra parity bit for error detection.
Extended versions use an extra bit, allowing for 256 characters.
Popularized by IBM.
Commonly used for data exchange between systems.

EBCDIC (Extended Binary Coded Decimal Interchange Code)

Uses 8 bits, representing 256 characters.
Also utilizes one extra parity bit for error detection.
Used in IBM mainframes and similar machines.
Circuits exist to convert characters between ASCII and EBCDIC.

Unicode

Developed to address the need for representing characters from multiple languages (Chinese, Korean, Japanese).
ASCII and EBCDIC were insufficient.
Unicode uses 16 bits, allowing for 65536 characters, plus an extra parity bit.
It tackles the problem of multilingual data representation.
Issues: waste of storage space, transmission time, lack of current OS support.
No consistent sort order.

Parity Check

Techniques to verify the correctness of transmitted characters.
A parity bit is added for each character.
Even Parity System: The total number of '1' bits (including the parity bit) must be even.
Odd Parity System: The total number of '1' bits must be odd.
Not foolproof: it can fail when an even number of bits are incorrect.

Languages, Operating System, and Software Packages

A computer only does what a programmer instructs it to do.
Programmers write sequences of instructions called programs.
Each instruction tells the computer to perform a specific task on data.
Computers understand machine language, while humans use natural languages.
Language acts as a bridge between humans and computers.

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Description

Explore the concepts of digital and hybrid computers in this quiz. Learn how digital technology represents information and the unique benefits that hybrid systems provide. Understand different classifications of computers based on data processing capabilities.