Data Capture Devices

Special p[purpose devices intended for us
in particular applications
Direct Data Input Devices
Sensing devices
Detect and pass the data directly to the
computer
i.e.
Production line
Supermarket checkout
In chemical works, Food factory or brewery
Bar Codes

In many libraries, every book has a bar-code
inside the front cover. This contains a number
which uniquely identifies the book. Each user
of the library is issued with a card which also
has a bar code printed on it. The coded
number uniquely identifies the user.
The library counter has on it a number of
terminals. These are connected directly to the
county library’s central computer. Each
terminal has a bar code reader in the form of
a hand-held ‘wand’.
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When a book is taken out, the librarian uses
the wand to read the bar code on the book
and then the bar code on the borrower’s card.
The central computer receives these
numbers and records the book loan in a
loans file.
When the book is returned, the librarian uses
the wand to read the bar code in the book.
This is automatically transmitted to the main
computer which deletes the loan from the
loans file.
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Magnetic Strip Cards




Advantages :
Easy and cheap to produce.
Not easily damaged.
Each stores a fairly large number of
characters (about 72)


Cuts down the amount of writing involved in a
transaction.
Disadvantages.
The data can be changed or erased by
magnetic fields.
The stripe can be damaged by scratching.
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Smart Cards
These have very thin memory chips
sealed into them. Some of the data in
them can be changed. One card can store
about 8000 characters.