ROM stands for Read Only Memory. The memory from which we can
only read but cannot write on it. This type of memory is non-volatile.
The information is stored permanently in such memories during
manufacture. A ROM stores such instructions that are required to start a
computer. This operation is referred to as bootstrap. ROM chips are not only used in the computer but also in other electronic items like washing machine and microwave oven.
Let us now discuss the various types of ROMs and their characteristics.
MROM (Masked ROM)
The very first ROMs were hard-wired devices that contained a
pre-programmed set of data or instructions. These kind of ROMs are known
as masked ROMs, which are inexpensive.
PROM (Programmable Read Only Memory)
PROM is read-only memory that can be modified only once by a user.
The user buys a blank PROM and enters the desired contents using a PROM
program. Inside the PROM chip, there are small fuses which are burnt
open during programming. It can be programmed only once and is not
erasable.
EPROM (Erasable and Programmable Read Only Memory)
EPROM can be erased by exposing it to ultra-violet light for a
duration of up to 40 minutes. Usually, an EPROM eraser achieves this
function. During programming, an electrical charge is trapped in an
insulated gate region. The charge is retained for more than 10 years
because the charge has no leakage path. For erasing this charge,
ultra-violet light is passed through a quartz crystal window (lid). This
exposure to ultra-violet light dissipates the charge. During normal
use, the quartz lid is sealed with a sticker.
EEPROM (Electrically Erasable and Programmable Read Only Memory)
EEPROM is programmed and erased electrically. It can be erased and
reprogrammed about ten thousand times. Both erasing and programming take
about 4 to 10 ms (millisecond). In EEPROM, any location can be
selectively erased and programmed. EEPROMs can be erased one byte at a
time, rather than erasing the entire chip. Hence, the process of
reprogramming is flexible but slow.
Advantages of ROM
The advantages of ROM are as follows −
- Non-volatile in nature
- Cannot be accidentally changed
- Cheaper than RAMs
- Easy to test
- More reliable than RAMs
- Static and do not require refreshing
- Contents are always known and can be verified
See more on Computer Tutorial
Always check for more updates. . .
If you would like to donate to Ykamazingworld please click here.
Check for more updates on Ykamazingworld Business List.
Check for more updates on Ykamazingworld Business List.
Click to view Director's Profile
To meet your needs with Ykamazingworld click on: http://metyourneeds.blogspot.com/
[Home Page] [Met your needs] [About Ykamazingworld Nigeria Enterprises] [Footwear and Leather Production] [Computer & Businesses] [Media and Communication Studios] [Films and Theatre Production Studios] [Vegetable Oil Dealer] [Home Planning & Building Engineer] Farm Food Production Fashion, Wears and Printing Production Home-made and Cosmetics Ice-block Depot, Drinks, Provision and Business Ventures [Ykamazingworld Search] [Carrier and Opportunity] [Company Overview] [Our Objectives] [Our Vision] [Our Goals] [Our Products] [Our Services] [Networking & Communications] [Consultancy] [Sales of Footwear and Leather Suppliers] [Computer Industrial Training (I.C.T)] [Footwear Industrial Training (F.I.T)] [Payment Rules and Regulation] [Sponsors or Fund Raising] [Ykamazingworld Proposals(for Partnerships)] [Ykamazingworld Banks & Accounts] [Social Media] [Our Address] [Our Contacts] [Ykamazingworld Weblinks] [GOto Blog] [GOto WebChatrooms] [GOto Books and Publishing] [GOto Word of Wisdom] [GOto Answers.com] [Notice for all our Clients]
Together, we rise to the future. . .
No comments:
Post a Comment