Jimbo

Thanks to both DaWei and Jimmy for the explanations

DaWei

A disk drive is easy enough to understand if you consider a simple, generic, single-platter, single-head implementation. We'll also stipulate that it's a magnetic medium. One could record analog signals on it, but we'll consider the digital implementation. We yank the magnetic domains around with an electromagnet (the head) in such a way that the north pole points either this way, or that way. Binary. We can dectect this difference when we come back to read.

We divide the disk into a number of concentric tracks (or cylinders). This is unlike the old records, where the groove was a spiral. We further divide the disk radially, into a number of sectors. Each sector will hold some number of bits. If you think about this for a second, you'll realize that the density of the bits, since there are the same number in each sector, will vary from the tracks near the center of the disk to those near the periphery. Since the outside tracks are moving faster, the bit-rate is the same. The density variation, however, does represent one problem (design consideration).

We call this device "random access" because we can pick any sector we like. Getting to a given sector is a two-part deal. First, we move the head to the track. You may do this by attaching the head to a lead-screw. Turning the lead-screw moves the head radially, from track to track. The time involved is the "seek time." There are issues regarding the accuracy of head/track alignment. Once we get to the desired track we have to wait for the desired sector to rotate around to the head. This is "latency." When the data arrives at the head, we pick it up, bit by bit, shift it into a shift register, accumulate a byte (or whatever quantity of bits we have designed for), and transfer it out in parallel, a chunk at a time. Obviously, the chunk transfer rate is bit-rate divided by chunk size.

If you want to pull up a spec and read what the density on your drive is, you can combine that with calculations involving RPM (revolutions per MINUTE!!!) and multiply it by any efficiencies you have introduced with multiple platters and/or multiple heads. You can figure out how fast you need to be to service that without dropping any on the floor. Your circuits can handle it, believe me. Whether or not a really busy processor can handle it all is simply a matter of loading. It's why DMA, dual-port memory, cache, and things of that ilk are used.

A side note on the use of the term, cylinders. If you consider a stack of platters, then the collection of track 0s, 1s, etc., from each platter represents a cylinder in the Z-axis. There is a historical reason also: early magnetic storage devices were often in the form of a cylinder, rather than a platter. Each track was, therefore, an actual physical cylinder.

One may, of course, introduce all sorts of organizational constraints on how one treats the physical organization of the medium. In bygone days, the system designers neglected to set aside a large enough number to count all the sectors on a modern drive. They had to resort to treating a group of sectors as a "cluster." Our predictions for the future are often too conservative. In a world of 64K machines, 640K was BOUND to be enough memory for the most profligate programmer, right?

__________________
Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code.
Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Harakim

Intel motherboards are good, but I would consider looking at the nVidia 590 board that is coming out for core duos. It is supposed to be really good. It uses some techniques to speed up your internet connection or to reduce lag.

It was supposed to come out about a week ago, but it looks like it might be 2 to 3 weeks before it does.

JimmyJim

Thats what i meant DaWie.If you read the reast of my post i think i said things along the same lines that its a machanical limitation and thats why the trend is for faster spinning drives. Its probably just my poor way i put it. I apoligise if i confused or mislead people by that badly worded statement.

And yeah i did change my avatar because i did not want people to think i was a mac fanboy. Now its the FreeBSD Daemon. It does not mean i am a FreeBSD fanboy however, its just a pic and thats that.

Edit: take a look at this:
http://www.engadget.com/2006/08/06/a...ntly-explodes/

Need i say any more about apple laptops (i do recognise battery problems are not necessarily the fault of apple but the battery manufacturer and that dell has had similar problems in the past)

Jimbo

Based on my quick reading of a random review I pulled off google, it seems to have a software package that essentially sets up QoS for your applications, but it won't speed up your connection.

Indigno

Jimmy, just because something is cheap does not automatically make it shit hardware. There is more to life than price.

__________________
Perhaps I should have a sticky topic for all of the times I "return" to this forum instead of a new one every time.

DaWei

There's a correlation between price and quality, but not a correspondence. People with successful products can take advantage of economies of scale that aren't available to new entries with limited markets.

Jimmy, I DID read all your post. I quoted the part that's bullshit. That's pretty plain. Whether it was posted as a mistaken viewpoint or as a miscommunication isn't germane. I do realize you have difficulty with large words such as "DaWei." That may spread over into your thinking, who knows?

__________________
Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code.
Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

JimmyJim

Chill out DaWie. You are not some all knowing god about computers. I do regcognise you have a fair bit of experience but you are not above any one here. I did not intentionaly spell your name wrong. I am sorry if by spelling David in such as silly way offended you.

I am getting fed up with some of your replies. You put people down just becuause they make a simple mistake in their spelling or grammer. You then try to make yourself look clever by posting some comment that is completely unreadable by useing words that dont even look like they derive from english. Or even worse you just reply with one of your stuipd smilies.

If you are just here to laugh at younger peoples ignorance then you can go fuck yourself. Everyone has the right to make mistakes while they learn. Your ego is so huge it makes you look like a bumbling old man sometimes. You remind me of Old Old Thrashbarg from The Hichhikers Guide to the Galaxy from time to time. Whenever someone questions you about computers you come up with some dribble that no one can understand.

The only reason why you have such a high number of posts is because there is a large number of then that are complete rubbish as no one can understand them. Maybe your too old for a forum where the average age of returning people here is less than 25!!!

DaWei

I may be too old, Jmmiy, but most of the young guys here wouldn't gag a maggot. Only bullshitter fakes, such as yourself. Chill your own ass out, boy. We all make mistakes, but when you post ridiculous technical fallacies, I'll call it as I see it. If your vocabulary is strained, buy a dictionary. If you don't want to see my posts, go to the control panel and use the ignore function. You could also just grow up. You obviously have some technical knowledge, but your need to strut the unstruttable leads you to silly blather. Go take your bipolar medicine and tell your mom she's calling you.

__________________
Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code.
Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

JimmyJim

Fuck you DaWie dont ever talk about my mum.

I have to put up everyday of my life with the fact that my mom is dieing of an incrueable brain disease. Its slowly sapping the life out of her. She cant walk, talk, eat by herself, she has issues with going to the toilet. The worst part is watching her everyday get worse. You made this personal now. If i ever met you in person i would beat the shit out of you. You are a useless piece of shit and you should retire to and old peoples home where you can die.

For your information i have been on anti depressents when i was 17, if you knew the first thing about depression or Bipolar disorder you would not even bring it up. I am a mature person who has had to put up with a lot of shit.

My technical knowlegde is good and in that post i made the simple mistake of putting it badly. Im not a god and i dont always have the time to read though my posts in detail.