Digital Electronics
and File Management
Unit D
1
Objectives
Introduce Digital Data
Representation
Introduce Integrated Circuits
Explore Processor Performance
Factors
Understand Computer Memory:
RAM
Explore Computer Memory
2
Objectives
Introduce Computer File Basics
Understand File Locations
Explore File Management
Understand Logical File Storage
Use Files
Understand Physical File Storage
3
Digital Data Representation
The form in which
information is conceived,
manipulated and recorded
on a digital device.
Uses discrete
digits/electronic signals
Byte = 8 bits = 1
character
4
Numeric Data
Consists of numbers
representing quantities
used in arithmetic
operations.
– Binary system, “Base 2”
- 1,0 (bits - binary digits)
- On/Off, Yes/No
5
Coding Systems
Depends on computer
File headers
ASCII (7 bits)
Extended ASCII (8 bits current PCs)
EBCIDIC (8 bits - older IBM
machines )
Unicode (16 bits - good for
languages - future)
6
Quantifying Bytes and Bits
Bit = b
Nibble = Half of a byte
Byte = B
Kilobyte (KB) (1024 bytes)
Megabyte (MB) (Million bytes)
Gigabyte (GB) (Billion bytes)
Terabyte (TB) (Trillion bytes)
7
Integrated Circuits
A super thin slice of semi–conducting
material packed with microscopic
circuit elements such as wires,
transistors, capacitors, logic gates,
and resistors. Bits are represented as
electrical pulses that travel over
these circuits.
Also called a chip, microchip
and computer chip.
8
Integrated Circuits (cont.)
Chips are classified by number of
components they contain
– SSI (small-scale integration), less than
100 components per chip
– ULSI (Ultra large-scale) over 1 million
Semi conducting materials used
to make chips
– Silicon and germanium
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Integrated Circuit Uses
processors
Memory
Support circuitry
Chip
Package
10
Processor Packages
DIPs (dual in-line packages)
DIMMs (dual in-line memory
modules)
PGAs (Pin-grid arrays)
SECs (single-edge contact
cartridges)
11
Microprocessor (Processor)
Designed to process instructions
Largest chip on motherboard
Intel: world’s largest chipmaker
(Pentiums)
AMD: Cheaper chips (Athlons)
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Motherboard
Main circuit board
13
Inside the System Unit
The system unit of a PC is the
case that houses processing
hardware and other hardware.
All of the hardware contained
within the system unit is
connected to the system board
or motherboard.
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CPU
The CPU (central processing
unit) does the vast majority of
processing for a computer.
CPUs contains a variety of
circuitry and components and are
connected to the motherboard.
Also called the processor or
microprocessor.
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CPU, Cont’d.
Processing speed (clock speed)
is measured in megahertz (MHz)
or gigahertz (GHz) and
measures the number of clock
ticks per second.
A computer word is a group of
bits or bytes that a CPU can
manipulate at one time.
Other factors that affect the
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Memory: RAM
RAM (random access memory) is the
computer’s main memory and is used to
temporarily storage programs and data with
which it is working.
RAM is volatile (erased when the power to the
PC goes off).
RAM comes in a variety of types, speeds, and
size. Types of RAM include:
DRAM
SRAM
SDRAM
DDR SDRAM
RDRAM
DDR-II SDRAM
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Memory: Other Types
Cache memory—fast memory chips
located on or close to the CPU chip
(L1, L2, and L3).
Registers—high speed memory built
into the CPU.
ROM (read-only memory)—non-
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Buses
Buses are electronic paths that
data travels around on a
computer system.
Internal buses move data
around within the CPU.
Expansion buses establish
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Expansion Slots and Cards
Expansion for desktop PCs.
– Expansion cards can be inserted into
expansion slots on the motherboard.
– Some external devices can be plugged into
existing USB or FireWire ports without
adding another expansion card.
PC cards—used with notebook
PCs.
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Ports
Connectors to which devices
can be attached.
Serial
Common
ports:

– Keyboard

Parallel
– Mouse

SCSI
– Monitor

USB

FireWire

Network
– Modem
– MIDI
– IrDA
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How the CPU Works
The CPU is a collection of electronic
circuits and components.
Impulses from an input device passes
through RAM and enters the CPU via a
system bus.
Within the CPU the impulses move
through the circuits and components to
create new impulses.
Eventually, a set of electronic impulses
leaves the CPU for an output device.
25
Typical CPU Components
Arithmetic/lo
gic unit
(ALU)
Control unit

Prefetch unit

Decode unit

Internal cache

Bus interface unit
Registers
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The System Clock and the
Machine Cycle
The system clock synchronizes
the computer’s operations.
The machine cycle is the series
of operations involved in the
execution of a single, machinelevel instruction.
– Fetch
– Decode
– Execute
– Store
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Making Computers Faster
Now and in the Future
Speeding up your system today.
– Add more memory.
– Perform system maintenance.
– Buy a larger or second hard drive.
– Upgrade your Internet connection.
– Upgrade your video card.
– Upgrade your CPU.
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Processor Components
31
Processor Performance
Speed: processor clock set clock
speed (MHz or GHz )
Word Size: number of bits the
processor can manipulate at one
time (32-bit or 64-bit)
Cache: high speed memory
(kilobytes)
32
Processor Performance
Instruction Set Type:
– CISC (Complete instruction set computer)
– RISC (Reduced instruction set computer)
Processing Technique:
– Serial
– Pipelining
– Parallel
Look at benchmark testing to
compare
33
Memory Types
Random Access Memory
(RAM)
Virtual Memory
Read-Only Memory (ROM)
CMOS
34
RAM
Random Access Memory
Temporary (volatile) holding area for
data, application software and operating
system
Expensive chip set
Circuitry
Less storage than disk
Capacitors hold bits
Capacity measured in MB (64 - 512 MB)
Speed in nanoseconds
35
Makes the most noticeable difference
RAM Types
SDRAM
– Synchronous Dynamic RAM
– fast and cheap
– DIMMS
– Most popular
RDRAM
– Rambus Dynamic RAM
– faster and more expensive
– RIMMs AND SO-RIMMs
36
Virtual Memory
Disk based
Stores parts of programs and
data until they are needed by the
processor
Works with RAM, but is slower
37
ROM
Read-Only Memory
Permanent on a chip from
manufacturer
Holds computer start up routine,
which are hard-wired instructions
– Only way to change is to replace ROM
chip
ROM BIOS (basic input/output
system)
38
CMOS
Complementary Metal Oxide Semiconductor
Battery powered
More permanent than RAM; less
permanent than ROM
Stores basic computer
configuration
Must be updated via CMOS setup
program when configuration
changed
39
Computer Ads
Includes: capacity, speed, and
type of RAM
Also maximum RAM that can be
installed
Example:
512 MB 400 MHZ SDRAM
capacity
speed
type
40
Computer File Characteristics
A collection of data on a storage
medium
Filename conventions
Filename extension
.txt
.jpg
.exe
.doc
41
File Locations
Device drive letters A: C: D:
Directory
– Root Directory (C:\)
– Subdirectory or folder (C:\Documents)
– File specification or Path
– File size and date
C:\Music\Reggae\Marley One Love.mp3
Drive
letter
Primary
folder
Secondary
folder
Filename
Filename
extension
42
Deleting Files
Move to Recycle Bin in Windows
Undelete
Empty Bin
43
File Management
Helps you organize your
computer files
File/Save and File/Open
Utilities like Windows Explorer or
MAC Finder
– list, find, move, copy, delete, rename
Save vs. Save As
44
Logical File Storage
Filing cabinet or tree
model
Metaphors to help
you visualize files on
a storage device
Windows Explorer
Folder hierarchy
45
Using Files
Start application (open Word)
Create file (type text)
Save file (File/Save)
Close file and application (File/Exit)
Open file again for editing (File/Open)
Edit file
Save file (with changes, or rename)
– File/Save
– File/Save As
46
Organizing Files
On your computer:
– Give files and folders descriptive names
– Keep file extensions so files open with
correct software
– Group similar files into folders
– Organize folders from top-down to make
retrieval and backup easier
47
Physical File Storage
Storage medium formatted
into tracks /sectors
electronically
File system keeps track of
names and file locations.
– Windows uses FAT32 OR NTFS
– Backup your index file
Clusters: a group of sectors
that speeds up storage and
retrieval
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Physical File Storage
FAT (File Allocation Table) on
each disk keeps track of where
all files are and which clusters
are empty. If damaged, you lose
everything.
Defragmentation Utility
rearranges files to be stored in
contiguous clusters.
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Tech talk: How a processor
executes instructions
Instruction Set is built into
processor
Instructional Cycle is the execution
of a single instruction
Fetch Instruction
Interpret Instruction
Execute Instruction
Increment Instruction Pointer
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Digital Electronics
and File Management
End
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Unit D: Digitals Electronics and File Management