Confuse with ROM...??

Posted on 2003-02-25
Medium Priority
Last Modified: 2010-04-03
1st Question

As I know ROM(Read Only Memory)is a permanent non-volatile storage is use to read only...
not to write right?
can you give me an example of ROM that we have in our computer system? izzit something like BIOS?

2nd Question

if this is TRUE....
now I want to ask the main quesion...
OUR Hard Disk Drive(HDD) is what?? ROM? DAM? SAM? EEPROM?
please reply asap..
any help will be highly apprieciated
Question by:joely2k
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Expert Comment

ID: 8016462
1) Yes the BIOS is a ROM (it contains the programs to make things like pc to start and reading writing to hardisk)

2) An hardisk would probobly be called a mass memory, you can read and write to it, and you store youre programs and data on the HDD.

The hardisk is not memory in the same way as ROM or RAM. The computer processor can not run programs directly from the HDD, but the programs are first loaded into RAM and run there.

The HDD is needed to store data that will stay there even tho the pc is shut down.

ROM will also keep its contens even if the pc is shut down, but as you cant write to it (among other things) you do need a mass storage or mass memory.

Normally just call HDD a HDD ':o)
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Expert Comment

ID: 8017673
I call the drive plaino HD, maybe 'cause I tire of 3-digit acromyns. Other than that, I think HippoDuck has supplied what I'd agree as the essentials here. But sometimes I get verbose and curious, so I'll add some padding. Curious part - not sure what you mean by SAM or DAM unless this is to distinguish static from dynamic, which is not part of the question. So IMO those acronymns can be ignored, aside from saying they'd be volatile memory (no good without power/electricity).

> use to read only... not to write right?

1) correct

> give me an example of ROM that we have in our computer system? izzit something like BIOS?

2) Yes.
2a) Bios is usually two separate chips on motherboard. Or was, many now using single chip.

2b) Video. There is also a chip of ROM for processing, displaying of video, now referred to as VGA (another acronym).

2c) Both BIOS (Basic I/O) and VGA have reserved memory locations below 1 MB, but above 640K. You can probably see more on this if when you boot up you go into BIOS setup. Many BIOS versions permit you a choice to dedicate some RAM to use in place of the ROM. There may be cache or shadow option. In any case, it is additional information source. If implemented, the tradeoff is you lose some general RAM from OS but you should get increased speed for the times when the ROM would have been accessed (RAM has superior speed to ROM)

2d) HD Controller. <what's its acronym? HDC?> As you may guess, it is for the disk I/O. It is more essential to have one of these when you up the count of HDs or increase size. Some may announce their presense at boot time, when after you have choice for changing BIOS you get another choice to manage HD, to affect boot order or perform low level format of change numerous other settings such as for LUN. Typically one would press <cntl>A to access it before Windows kicks in.

> OUR Hard Disk Drive(HDD) is what??

3) As HippoDuck says, we don't talk that way, we refer to it as mass storage. Now we have CD and DVD, other mass storage devices. HD memory can be changed, but it remains when power is removed. The reason is that unlike RAM, the bits used to make data do not need power. The disk surface is physically changed to represent the data.

4) Now I've questions for you. How about CMOS? EPROM? WORM? If interested.

Author Comment

ID: 8018461
CMOS?abbrievation for complementary metal-oxide semiconductor...
but as I know izzit a battery for keeping our date,time, BIOS system info??

EPROM,Erasable and programable ROM that I learn before but can you give me some example of it?

WORM? virus? or the write-once read-many like the CD??
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Expert Comment

ID: 8019790
When you turn off your pc the centrall memory RAM looses is contens.

To be able to get the pc up and running again when you turn on the puter, there must be a program that instructs the processor what to do.

The processor is unable to run programs from HDD and the RAM is empty now, so the only place a program can be runned from is the BIOS.

The BIOS can be ROM memory or EPROM. It can probobly also be some other type of ROM.

If you need to uppdate your BIOS (to support new hardware) you would have to take out the ROM chip and replace it with a new one (well 20 years agoo maybe :P)

If you have an programmable ROM like an EPROM, it is possibble to erase the contence of the ROM and write (?) new data into it.

Well now, ROM is read only :P but still you can do this, tho it is very slow, compared to RAM.

So to be able to uppgrade the BIOS more easely, enginers has come up with programmable ROM.

So basically stuff that never or very seldom changes can be writen to EPROM.

But a pc needs also to save some changeing values to a memory that will survive, even if you turn of the pc.

The date and time that changes every second, the hardware setup settings that is specific to your pc and your preferences.

For this the slow EPROM is no good, nor the empty RAM, or the HDD that the processor will not be able to read @ this point (startup)

So these settings are stored in the CMOS memory that is battery backuped with a small battery.

The pc word is full of words and acronymes that can mean compleatly different things :P

Yes worm is a type of virus, and if you found a WORM CD I belive you when you say it means "write-once read-many" tho I only heard of CDR and CDRW.

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Expert Comment

ID: 8033855
As you have asked 'permanent non-volatile storage' I guess you mean permanent in that it cannot be changed rather than physically permanent in a pc. The obvious item is a CDROM. The music CDROM is perhaps the ubiquitous example.

The problem with quoting the bios as a ROM is that, as has been said already, it is possible to modify the info in the bios so it is not strictly permanent. Apart from which as has also been said already its onfo is kept live by an external battery so in fact the bios info is in part volatile. Removal of the power source then reduces it to its original ROM state. So its a yes and a no on the bios.

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Expert Comment

by:Silver Shroud
ID: 8044541
New BIOS storage is EEPROM. [electrically erasable programmable read-only memory]
It no longer relies on the battery.
That is why flashing the BIOS is no longer the messy, potentially fatal operation it used to be.
The battery is, mainly for clock support, these days.

Expert Comment

ID: 8046667
To start with the second question on your first post, a Hard Drive is a magnetic plate that stores information permanently. It is actually similar to the operation of a floppy disk or even a cassette tape, because ultimately all rely on magnetic encoding of information. Once a certain piece of data is written, the medium is actually aligned in a certain way as to represent binary information; in "0"s and "1"s. Although it is non-volatile - that is, it does not lose it data once power is disconnected - any close encounters with an actual magnet (like the horseshoe ones) will actually cause the medium filament to realign, according to the poles of the magnet in close contact to it. So basically, you pretty much lose all of your data. That's why there are always disclaimers not to keep floppy disks near magnetic fields or actual magnets. In essence, it is not classified as any of those storage types you gave in the first post.

Secondly, as many of my colleagues alluded to, BIOS is an example of an EEPROM, because it is electrically eraseable. The old types (EPROMS) would be erased by shining ultraviolet radiation on the chip itself, causing certain reactions that can only be described in detail when you take courses on Digital electronics manufacturing. EEPROMs work by sending specific voltage levels that trigger a complete reset of the transistors in the ROM chip.

As for your second post, CMOS keeps track of your peripheral settings, enhanced RAM capabilities, time, date, hardware detection through IDE and SCSI, bootup sequence, and many other functions that you would love to play with to optimize performance...that is if you know what you're doing :D. WORMs are "Write-Once Read Many times" storage media, like a CD-RW and DVD-RAM. There are also kinds of similar storage that are all but obselete, such as floptical disks and magento-optical disks.
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Expert Comment

ID: 9990500
1. yes, BIOS is one good example.
2. hard disk is external storage, ROM is kind of internal storage (memory) but it is read-only rather than RAM.
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by:Silver Shroud
ID: 9990771
PAQ this lost thread.
No point refund.
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ID: 9990787
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by:Silver Shroud
ID: 9990829
My comment is intended as a recommendation for the cleanup moderator who will eventually get to this lost question.
The last post was almost 9 months ago.
joely2k asked an involved question, offered a silly 20 points, and then took the information received without bothering to award those points.

This thread has some good information in it and should be turned into a Previously Asked Question [PAQ] for reference instead of being deleted.
joely2k got a LOT more information than they paid for with that pathetic point offer. Therefore no refund.
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Expert Comment

ID: 10097362
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

PAQ/No refund (as recommended by StoneG)

Please leave any comments here within the next seven days.


EE Cleanup Volunteer

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PAQed - no points refunded (of 20)

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