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ITEC 1000 Study Guide - Final Guide: Memory Buffer Register, Wav, Exclusive Or

Information Technology
Course Code
ITEC 1000
Peter Khaiter
Study Guide

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ITEC 1000 Cheat Sheet
Number of Symbols in Languages:
o The ASCII table has 128 unique symbols.
o The EBCDIC table has 256 unique symbols.
o 65,536 characters can be represented in UNICODE.
Levels of RAID (Redundant Array of Inexpensive Disks):
o RAID 0: Data is striped across all of the disks for fast access, but due to the
lack of redundancy, a failure in any one block corrupts all of the data in the
o RAID 1: Provides protection by storing everything at least twice so that if one
disk gets fried the other can keep working. This causes a slight drag in
performance. (also known as “disk mirroring”)
o RAID 3: Same as R0, but also reserves one dedicated disk for error correction
data and has good performance with some level of tolerance.
o RAID 5: Is by far the most common RAID config. and is similar to RAID 0.
It consists of 3 or more disks that are all striped together and the equivalent of
one drive is hold parity information. (i.e. you have 3 500GB HDDs in R5 but
you will only have 1TB of storage.) If two drives fail in R5 the data is lost.
Dot Pitch:
o Is a measure of the diagonal distance between phosphor dots(pixels) on a
display screen.
o The lower the dot pitch, the crisper the image.
o It is cited in mm and has a typical range from 0.15 to 0.30 mm.
o Calculating dot pitch:
Length of Z Z = (L^2 + H^2)^1/2 (Answer in inches)
screen 1mm = 0.039mm
Height of screen
X = Size of monitor / Z (in inches)
Dot pitch = X / 0.039 (in mm)
Aspect ratio:
o Aspect ratio is the ratio of the width to height of a display screen(4:3 on most
displays and 16:9 on high def. displays)
Types of I/O:
o Programed I/O:
Transfers one word at a time.
Is very slow.
INPUT: I/0 device >I/O module>I/O register>AR under program
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OUTPUT: AR>I/O register>I/O module>I/O device.
Primary uses:
Communication with I/O modules to control I/O operations.
o Interrupt-driven I/O:
A signal that causes the CPU to alter its normal flow of a
program/instruction execution.
Unexpected input
Abnormal situation
Illegal instructions
Multitasking, multiprocessing
o Direct Memory Access (DMA)
Used for high-speed data transfers between an I/O device and memory
in blocks.
During the transfer, the CPU is NOT involved.
Typical devices include: Disk drives, and tape drives.
HDD Calculations:
o Seek Time:
The time it takes the head to move to the correct track. Specified as an
average for all tracks on the disk surface. Average time to move from
one track to another.
o Latency Time:
The time for the correct block to arrive at the head once the head is
positioned at the correct track. Specified as an average, in other words,
½ the period rotation. (a.k.a. “rotational delay”)
Avg. Latency time = (1/2) * (1 / rotational speed)
o Access Time:
It is the time “to get to” the data.
Access time = seek time + latency
o Transfer Time:
1 / (# of sectors * rotational speed)
o Total Time to Retrieve a Disk Block:
Avg. seek time + Avg. latency time + Avg. transfer time
Data Formats:
o Video:
Requires a massive amount of data
A video producing full screen 640x480 pixel true colour image
at 30 fps takes 27.65 MB of data/sec.
Options for reducing file size may include: decreasing the size of the
image, limiting the number of colours, or reducing the frame rate.
o Audio:
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