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Is there a difference between the terms OS and ROM?

Perusing the web, I get the impression that a phone's ROM is an image of an OS that's been installed to a phone, so the two terms are roughly equivalent - is this correct?
 
OS == Operating System. It is the software that runs the system. Windows is an Operating System, as are Mac OS X, Linux, and Solaris. Android devices run the Linux OS. Linux is open source, and Google maintains that openness with Android.

ROM == Read Only Memory. It usually describes a piece of hardware, a memory chip that you normally can't write to. Device manufacturers will typically use ROM to store the OS to help ensure the devices maintains a known state and is thus more reliable and easier to support.

Rooting your phone is a way to give yourself enough access to write to protected parts of the file system and alter the OS. People tend to use the phrase ROM in these types of forums to refer to a complete image that contains an OS which you can load on your phone.
 
Howzit ballhands76!

When some1 says ROM they technically mean EPROM / EEPROM (electronically erasable programmable read only memory)

ROM is only for reading and not for writing / or reprogramming... the correct term is EPROM. Like a CD or DVD...

Today EPROM chips can "read" and "write" like transflash / usb stick :)

Hope this helps dude ;)

Stinks
 
I think I get it. Thanks to everyone for all your help!

Can you explain what you mean by "made accessible"?

takeshi, what I meant was which exactly is open-source, the OS or the ROM, in case there was a difference. I take it that the OS is open-source and modifiable, and a modified OS can theoretically be installed as a ROM image on a phone.
 
For most intent and purposes, ROM and OS are the same on an android. The same goes for firmware.

The Android OS is definitely open source. But are manufacturer roms open source? Possibly not. Google allows individual companies to customize the android OS interface, and those modifications are not open source.
 
some clarification...
ROM .. the TERM is used in many areas and with different meanings.

OS = Operating System

some OS are open source.
Android is an open source OS.

Android OS is packaged into a file with other needed parts .. to be loaded on to devices.
this file is called a ROM. (I don't know what the letters stand for here)

some developers take the open source Android OS.. change it up ... customize it.
repackage it into a custom ROM to be loaded into specific mobile devices.
 
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So what I got out of this is depending on what state the os or rom is in basically dictates the name. Rom is a file waiting to be loaded and executed and once that takes place it become the os/operating system.
yes...you got it.

once the custom rom is flashed it becomes the os, but we still call it by the name of the rom and not what os the rom is based on.
 
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