The Hexadecimal Number System and Memory Addressing

hexadecimal

A number system based on 16 values (called base 16); uses a combination of 16 numerals (0 - 9) and letters (A - F.)

base 2, or binary

A numbering system that can be supported by the expression of only two numerals is called what?

ASCII

Acronym for American Standard Code for Information Interchange.

hex number system

Computers often display memory addresses in this number system.

True

T or F: The A and B ranges of upper memory addresses (upper memory addresses that begin with A or B when written in hex) are used for monochrome monitors.

True

T or F: The actual memory address is calculated by adding a zero to the right of the segment address and adding the offset value, like this: C800:5 = C8000 + 5 = C8005.

True

T or F: The offset value can have as many as four hex digits.

True

T or F: This book follows the convention of placing a lowercase h after a hex number, like this: 2Eh.

True

T or F: Understanding the number system and the coding system that computers use to store data and communicate with each other is fundamental to understanding how computers work.

True

T or F: Writing numbers raised to a power is the same as multiplying that number by itself the power number of times.

They begin with A or B, when written in hex.

The A and B ranges of upper memory addresses begin with these two letters, when written in hex.

memory

The DOS DEBUG command displays contents of this.

One zero

The actual memory address is calculated by placing this to the right side of the segment address and adding the resulting value to the offset value.

conventional memory

The first 640K of Windows 9x or DOS memory is called this.

Ada Lovelace

The numbering system that can be supported by the expression of only two numerals, called base 2, or binary, and uses the numerals 0 and 1, was originally invented by whom?

The segment address

The part to the left of the colon in a memory address (for example: C800, in the memory address: C800:5) is called what?

The offset

The part to the right of the colon in a memory address (for example: 5, in the memory address: C800:5) is called what?

Hexadecimal numbers

These are usually written in groups of four bits.

The byte

This has become the universal single unit of data storage in computers everywhere.

Gigabyte

This is 1000 megabytes or 1024 megabytes, depending on what has come to be standard practice in different situations.

Kilobyte

This is 1024 bytes, which is 2 to the 10th power; often rounded to 1000 bytes.

Bit

This is a numeral in the binary number system: such as 0 or a 1.

Megabyte

This is either 1024 kilobytes or 1000 kilobytes, depending on what has come to be standard practice in different situations.

640K = 640 × 1024 = 655,360

This is how 640K memory is addressed, first in decimal and then in hex (assuming 1 kilobyte = 1024 bytes).

Hex

This is short nomenclature for hexadecimal.

ASCII, or American Standard Code for Information Interchange

This is the most widespread binary coding scheme for microcomputers, which is recognized as the microcomputer standard.

C:\> DEBUG

To enter DEBUG, type this command at the C prompt and press <Enter>.

The letter Q for Quit.

To exit DEBUG, type this letter for quit and press Enter at the hyphen prompt.

True

Tor F: The A area of memory (the beginning of upper memory) is NOT used UNLESS the computer is using a monochrome monitor or this area is being used as an upper memory block.

1000 kilobytes

When calculating floppy disk capacities, 1 megabyte = this many kilobytes.

1024 kilobytes

When calculating hard drive capacity, traditionally, 1 megabyte = this many kilobytes.

John Atanasoff

Who proposed using a coding system that expressed everything in terms of different sequences of only two numerals: one represented by the presence of a charge and one represented by the absence of a charge.

memory "dump"

You create this when you tell the system to record the contents of memory to a file or display it on screen

True

T or F: It is much easier for human beings to read hex numbers than to read binary numbers.

True

T or F: Memory addresses are displayed as two hex numbers. An example is C800:5.

False

T or F: One skill a knowledgeable computer support person does NOT need is the ability to read hex numbers and convert hex to decimal and decimal to hex.

A decimal number system with the digits 0-9.

Early attempts to invent an electronic computing device met with disappointing results as long as inventors tried to use what number system?

A byte

In ASCII, each character is assigned an 8-bit code called this.

16 bytes

Memory is displayed showing this many bytes on each line.

bits

Short nomenclature for 'binary digits."

False

T or F: A dump is NOT useful when troubleshooting

True

T or F: Every character or number entered into a computer is first converted into a series of 0s and 1s.

True

T or F: It is easier for computers to convert from binary to hex or from hex to binary than to convert between binary and decimal.

True

T or F: Sometimes a hex number is preceded by 0x, as in 0×FF.