– THERE IS MECHANICAL CONTACT
BETWEEN THE PRINT HEAD AND PAPER
NON IMPACT PRINTERS
– THERE IS NO MECHANICAL CONTACT
BETWEEN THE PRINT HEAD AND PAPER,
PRINTING WILL TAKE PLACE AS
IMPACT PRINTERS EXAMPLE
1. LINE PRINTERS
– DRUM PRINTER
CONSIST OF CYLINDRICAL DRUM ON
WHICH CHARACTERS ARE EMBOSSED
– CHAIN PRINTER
CONSISTS OF A STEEL BAND ON WHICH ON
WHICH THE CHARACTERS ARE EMBOSSED
– CHARACTER PRINTER PRINTS ONE
CHARACTER AT A TIME, WITH THE
PRINT HEAD MOVING ACROSS A LINE,
NORMALLY PRINT 30 TO 300
CHARACTERS PER SECOND..
– THERE ARE TWO TYPES
DOT MATRIX PRINTERS
– Printing haead contains a vertical group
(array) of pins.
– There are 9 pins in the print head,
bottom 2 used to lower case, others for
LETTER QUALITY PRINTERS
– This type of printer will print full
characters not as the character made of
This lesson includes the following sections:
• Overview of Printers
• Dot Matrix Printers
• Ink Jet Printers
• Laser Printers
• Snapshot Printers
• Other High-Quality Printers
Overview of Printers
• Categorizing Printers
• Evaluating Printers
Overview of Printers - Categorizing Printers
Printers fall into two categories:
• Impact printers use a device to strike an inked
ribbon, pressing ink from the ribbon onto the paper.
• Non-impact printers use different methods to place
ink (or another substance) on the page.
Overview of Printers - Evaluating Printers
When evaluating printers, consider four criteria:
• Image quality – Measured in dots per inch (dpi). Most
printers produce 300 – 600 dpi.
• Speed – Measured in pages per minute (ppm) or
characters per second (cps).
• Initial cost – Consumer printers cost $250 or less, but
professional printers can cost thousands of dollars.
• Cost of operation – This refers to the cost of supplies
used by the printer.
Dot Matrix Printers
• How Do Dot Matrix Printers Work?
Dot Matrix Printers -
How Do Dot Matrix Printers Work?
• Dot matrix printers are a common type of impact
• A dot matrix printer's print head contains a cluster
of pins. The printer can push the pins out to form
patterns in rapid sequence.
• The pins press an inked ribbon against the paper,
creating an image.
Dot Matrix Printers - Performance
• Lower-resolution dot matrix printers use nine pins.
Higher-resolution models have 24 pins.
• Speed is measured in characters per second (cps).
Some dot matrix printers print 500 cps.
Ink Jet Printers
• How Do Ink Jet Printers Work?
Ink Jet Printers –
How Do Ink Jet Printers Work?
• Ink jet printers are an example of non-impact
• The printer sprays tiny droplets of ink onto the
• Ink jet printers are available for color and black-and-
Ink Jet Printers - Performance
• Ink jet printers offer speeds of (2 – 4 pages per
minute ppm) and resolution (300 – 600 dots per
inch dpi), comparable to low-end laser printers.
• Ink jet printers are inexpensive and have low
• How Do Laser Printers Work?
Laser Printers –
How Do Laser Printers Work?
• Laser printers are non-impact printers.
• They use heat and pressure to bond particles of
toner to paper.
• Laser printers are available for color and black-
Laser Printers - Performance
• Laser printers provide resolutions from 300 – 1200
dpi and higher.
• Black-and-white laser printers usually produce 4 –
• Laser printers produce higher-quality print than
ink jet printers, but are more expensive.
• Snapshot printers are specialized, small-format
printers that print digital photographs.
• Snapshot printers are fairly slow, and can be more
expensive to operate
Snapshot printers are popular among
digital camera users
Other High-Quality Printers
Print shops and publishers use these printers to create
high-quality color images:
Plotters use mechanical, ink jet, or thermal technology
to create large-format images for architectural or
Re vie w
• List the three most commonly used types of printers.
• List the four criteria you should consider when
• Describe how a dot matrix printer creates an image
on a page.
• Explain the process by which a laser printer
• List five types of high-quality printing devices
commonly used in business.
AN ESSENTIAL COMPONENT OF EVERY COMPUTER IS ITS
EACH AND EVERY WORD IS ASSIGNED AN ADDRESS IN THE
EACH WORD CONSISTS OF SAME BITS IS CALLED WORD LENGTH.
MEMORIES CAN BE READ FROM OR WRITTEN INTO
MEMORIES THAT CAN BE BOTH READ FROM AND WRITTEN INTO
ARE CALLED READ-WRITE MOMORIES.
SOME MEMORIES HAVE PROGRAM OR DATA PERMANENTLY
STORED AND ARE CALLED READ ONLY MEMORY.
THERE ARE TWO TYPES OF MEMORY DEVICE
PRIMARY MEMORY (RAM, ROM)
SECONDARY MEMORY (HARD DISK, FLOPPY, CD, PEN DRIVE)
THERE ARE TWO TYPES OF RAM
DYNAMIC RAM (DRAM)
DRAM CONSISTS OF A TRANSISTOR AND CAPACITOR.
CAPACITOR THAT’S CAPABLE OF STORING AN ELECTRIC
CHARGE DEPENDING ON THE SWITCHING ACTION OF THE
CAPACITOR EITHER CONTAIN NO CHARGE (0 BIT) OR DOES
HOLD A CHARGE (1BIT)
DRAM PROVIDES VOLATILE STORAGE IT MEANS IF POWER
FAILURE MEANS IT WILL LOST ITS MEMORY
DRAM CONTAINS TWO ELEMENTS
MOSFET (METAL OXIDE SEMICONDUCTOR
FIELD EFFECT TRANSISTOR)
EACH CHIP WILL HAVE THE STORAGE
CAPACITY OF 64 BIT.
THE AMOUNT OF TIME TAKEN TO
PRODUCE DATA REQUIRED FROM
MEMORY, FROM THE START OF ACCESS
UNTIL THE AVAILABLILITY OF DATA IS
CALLED MEMORY ACCESS TIME.
DRAM CHIPS HAVE ACCESS TIME
RANGING FROM BELOW 7 TO 70
DRAM CELL CONSISTS OF ONLY ONE
TRANSISTOR AND CAPACITOR PER BIT
GENERALLY DRAM CHIPS ARE
AVAILABLE WITH 128 BIT OR 256 BIT
DENSITIES OR MORE
THE PROBLEM OF CAPACITOR IS THAT IT
STARTS LOSING THE CHARGE OVER A
PERIOD OF TIME
THEREFORE THE MEMORY CONTROLLER
NEEDS TO REFRESH THE MEMORY
CONTENTS AS MANY AS THOUSAND
TIMES A SECOND, WHICH IS CALLED
Extended Data Out Dynamic Random Access
Memory, a type of DRAM that is faster than
conventional DRAM. Unlike conventional
DRAM which can only access one block of data
at a time, EDO RAM can start fetching the next
block of memory at the same time that it sends
the previous block to the CPU.
It has a dual pipeline architecture
BECAUSE OF NUMBER OF WIRES IN A SINGLE
CABLE(MULTIPLEXING) , EDO DRAM CHIPS CANNOT
OPERATE IN LOCK AND STEP INTO THEIR HOST
THIS IS CALLED ASYNCHRONOUS MEMORY
THIS WILL KEEP THE MEMORY BUS SPEED LIMITED TO
TO REDUCE THIS PROBLEM, IT WAS MADE POSSIBLE BY
REDESIGNING THE BASIC MEMORY CHIP INTERFACE
CALLED SYNCHRONISED DRAM
DOUBLE DATA RATE (DDR) SDRAM
THIS RAM IS FAIRLY FAST, AND IT WIL TRIED TO ADDRESS
SOME OF THE COMPLEX ELECTRICAL AND PHYSICAL
PROBLEMS INVOLVED WITH MEMORY.
RDRAM IS NOT MULTIPLEXING, RATHER THAN IT
CREATES INDEPENDENT CONTROL.
SDRAM WIL SUPPORTS ONE OPERATION IN EACH CLOCK
BUT DDR SDRAM CAN DO TWO OPERATION PER CLOCK
SO THAT IT HAS DOUBLING THE MEMORY BANDWITDTH
IT IS ALSO A VOLATILE BUT AS LONG AS
THEY ARE SUPPLIED WITH POWER.
THAT MEANS IF POWER GOES MEANS IT
WILL STORE THE BINARY FORMAT OF
CONTENTS, IT WILL REMAINS TO THE
SYSTEM WHEN POWER IS APPLIED TO THE