Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Where are ROM, PROM, EPROM, EEPROM are physically present in a PC.

Status
Not open for further replies.

anand_jha_30

Member level 2
Joined
Oct 29, 2010
Messages
50
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
1,615
Where are ROM, PROM, EPROM and EEPROM are physically present in a simple desktop computer? Are they all present? How they look like? Whats the function of each?
 

betwixt

Super Moderator
Staff member
Joined
Jul 4, 2009
Messages
14,707
Helped
4,807
Reputation
9,631
Reaction score
4,588
Trophy points
1,393
Location
Aberdyfi, West Wales, UK
Activity points
125,273
ROM, PROM or EPROM are used to store information which must be retained when the power is off, typically they would be used to store the BIOS code.
ROM and PROM are memory types which cannot be erased by electrical signals (provided they are not sufficient to damage it!).
The difference between them is:
ROM is normally 'mask programmed' during manufacture. The data is part of the photographic image used to make the IC.
PROM is an empty memory which can be electrically programmed once only, it has no erase function. They allow latest software version to be programmed permanently.
EPROM can be erased and reprogrammed - for example when upgrading a BIOS.

EEPROM is quite different, it is a memory which is designed to be reprogrammed more frequenty, for example the BIOS configuration settings. It can be treated almost like RAM except it retains its contents when power is removed.

Most computers will use one of ROM, PROM or EPROM but probably not all of them.

Brian.
 

anand_jha_30

Member level 2
Joined
Oct 29, 2010
Messages
50
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
1,615
Thanks for quick reply. How these memories look like? Are they simply IC chips? Also where are they physically present for example I can locate the RAM in one of the slots on my mother board. Also how can I know which of them are present on my PC.
 

srizbf

Advanced Member level 5
Joined
Apr 3, 2010
Messages
1,995
Helped
417
Reputation
840
Reaction score
328
Trophy points
1,363
Activity points
10,985
the ROM equivalent in PC can be located by identifying the chip marked as 'bios'
usually a silvered paper pasted chip with marking like 'ami bios , award bios ' etc.
they are flash types in current pcs.

an eeprom or similar is there. but you cannot identify separately.
if you can locate rtc chip , then internally it has that.
 

betwixt

Super Moderator
Staff member
Joined
Jul 4, 2009
Messages
14,707
Helped
4,807
Reputation
9,631
Reaction score
4,588
Trophy points
1,393
Location
Aberdyfi, West Wales, UK
Activity points
125,273
Yes, they all look like little black plastic boxes! @srizbf's description is a good as it can be and quite right in saying that in modern systems the ROM/PROM/EPROM has largely been superceded by flash technology. Flash is similar to EEPROM in operation but is normally heavily protected to prevent accidental corruption and special software is needed to 'unlock' it so it's contents can be changed.

Brian.
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
47,959
Helped
14,145
Reputation
28,549
Reaction score
12,831
Trophy points
1,393
Location
Bochum, Germany
Activity points
278,225
Besides the PC mainboard, also "intelligent" peripherals like graphic cards or supplemental interfaces have their own BIOS flash. Small capacity serial EEPROMS are used to hold the MAC address of ethernet cards.
 

betwixt

Super Moderator
Staff member
Joined
Jul 4, 2009
Messages
14,707
Helped
4,807
Reputation
9,631
Reaction score
4,588
Trophy points
1,393
Location
Aberdyfi, West Wales, UK
Activity points
125,273
We missed one: there is often a tiny eeprom on the RAM sticks. It holds information on the serial number and type of main RAM on the stick so the motherboard can adjust the signal timing automatically.

Brian.
 
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top