# How Computers Communicate

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### How ComputersCommunicate :

How ComputersCommunicate 4

### Analog :

Analog Analog electronics use and produce varying voltage levels.

### Digital :

Digital Digital electronics use and produce discrete voltage levels.

### Computer Data :

Computer Data Can be expressed by voltage levels, numeric systems, and symbolic codes. Numeric systems: Binary number system. Hexadecimal number system. Symbolic codes: ASCII.

### Binary Number Code :

Binary Number Code 0 + 64 + 32 + 16 + 0 + 0 + 2 + 0 = 114 Binary = 01110010 Decimal = 114

Hexadecimal Number Code Based on the number base 16. Uses 16 characters. Uses numerals 0–9 and characters A–F. Matches the hardware system of most computers. Data lines in a computer are 8, 16, 32, or 64 lines wide. Memory sizes are in increments of 8 and 16.

Hexadecimal Conversion Hex = 20 Decimal = 32 (16 x 2) + (1 x 0) = 32 (16 x A) + (1 x 4) = 164 Hex = A4 Decimal = 164

### ASCII Code :

ASCII Code American Standard Code for Information Interchange. First attempt to standardize computer character codes. Unique to certain systems, such as IBM. Must be used with compatible software.

ASCII Code Chart

### Bits, Bytes, and Words :

Bits, Bytes, and Words

### Serial and Parallel Data Transfer :

Serial and Parallel Data Transfer Serial transfers one bit at a time. Parallel transfers multiple bits at a time.

### Computer Numerical Values :

Computer Numerical Values Metric prefixes are commonly used to express speed and size of computer systems and hardware. Used in combination with the words bit (b) and byte (B): bps (bits per second). Bps (bytes per second). 256 MB (256 Megabytes).

Metric Prefixes

### Base 10 and Base 2 Comparisons :

Base 10 and Base 2 Comparisons Use base 2 number system when referring to bits and bytes.

### Power-On Sequence :

Power-On Sequence Ac power is converted to dc and distributed to the major components of the computer system. 1 BIOS checks components in the system to ensure they are in working order. This is called the power-on self-test (POST). 2 The operating system takes control of the system. 3 The CPU waits for activity. 4

### Major Parts Working Together Example :

Major Parts Working Together Example CPU waits for activity. 1 When a user opens a program, the program shares control with the CPU. 2 When a user saves data, the program issues the save command, and the operating system takes over and works with the BIOS to complete the operation. 3 The BIOS translates the save instructions to the disk system. 4 Control is returned to the operating system. 5

### Review :

Review Name three ways with which data can be expressed. Voltage levels. Number systems, such as binary and hexadecimal. ASCII code.

### Review :

Review Describe the power-on sequence. Ac power is converted to dc and distributed to the major components of the computer system. BIOS checks components in the system to ensure they are in working order. This is called the power-on self-test (POST). The operating system takes control of the system. The CPU waits for activity.

### Review :

Review Describe what happens when a user saves data. The program issues the save command, and the operating system takes over and works with the BIOS to complete the operation. The BIOS translates the save instructions to the disk system. Control is returned to the operating system.

### Review :

Review What is the nominal value of 1 MB? 1,000,000

### Review :

Review What is the value of 1 MB based on the binary system? 1,048,576 (220)