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Discussion in 'iPad FAQ' started by Flotzie, Mar 23, 2011.
Does anyone know which of these uses the most memory. Is it the cache?
Safari's History and Bookmarks are stored in flash memory, while the cache is in system RAM. Because the iPad1 has relatively little system memory (256 MB) the cache can often 'overflow' the available system RAM - particularly (a) if you try to load multiple pages that are graphics intensive or (b) you switch to another app that requires system memory. As a result, when you return to a page that you've previously left, Safari may need to reload the original page - which can be annoying. I've read reports that this is now better on the iPad2 because it has 512 MB RAM. I find it annoying when you are, for example, typing iPad Forum posts into the iPad Forum website 'Message' box and need to swap to another page to get some information for your post. When you return, it may be the case that Safari has to reload the original iPad Forum page but, because the message text had not been saved but only cached, it is lost and you have to enter it again.
History, Bookmarks etc are stored in the iPad's Flash filing system and consume negligible Flash storage.
The ability to clear the cache and history in the iPad 'Settings' app is more for security - so that, if you've been doing some online banking and want to loan your iPad to a co-worker, you can clear all that personal information out of the iPad.
I forgot to mention that cookies are stored in flash memory too, so they're not an issue in page refreshes.
Thankyou Tim that was a great answer.
So am i right in thinking my 16 Gb iPad has as follows:
16Gb of main memory (solid state). Containg music, video, etc?
256Mb system memory (is this equivalent to the RAM memoery in a PC?) For the cache
And 'X' amount of flash memoory for cookies and history?
What size is the flash memory and is it RAM?
Just trying to learn.........
The 16 GB of main memory (solid state) is the flash memory.
256 MB of system memory - yes, RAM, and equivalent to the RAM in a PC.
The Flash is the equivalent of the PC's hard disc.
Cookies, history, bookmarks are kept on the flash because that's non-volatile - i.e. it stays there even when the power is off.
System memory - RAM - 'disappears' when the power goes off.
So anything the iPad wants to keep - cookies, history, bookmarks - it needs to put in the flash memory. Stuff that it doesn't want to keep - cache - it keeps in RAM.
Also RAM is fast - so it's used for things the iPad needs rapid access to. Flash is relatively slow compared to RAM (though much faster than your PC's hard disc) so it's used for less-frequently accessed information.
Thanks for your post - please don't hesitate to ask anything else. We all love the iPad here - the iPad Forum is a group of enthusiasts, none of us are paid or work for Apple, so we do it because we love it and we don't always have to agree with Apple!!
Enjoy your iPad and, yes, you'll get even more enjoyment and fun as you understand a little more about what makes it so 'magical'.
So if the cache is stored in the RAM memory. Is the cache cleared when you power off?
But it's not cleared if you just put it to sleep?
Wow - you've got me there!! I'll have to think about that, but I'm pretty certain you're right. I'll give it a try - an experiment for later this afternoon. As you've seen, the cache gets 'flushed' quite frequently if other apps or web pages need the RAM. You can see that when you try to return to a web page - sometimes it comes up immediately, because the page is still in cache, other times it has to be reloaded, when the cache copy of that page has been flushed to make room for something else.
I learn something new every day on this Forum!!
I'm wouldn't put any credence to what I say, it's bound to be wrong!
I understand what you mean about sometimes web pages not being stored in the cache. This morning I was typing a message into a website contact form, but halfway through had to check an address in the contacts book. When returning to the webpage, it had to reload and I'd lost what I'd typed.
Don't be so modest - it's fun finding these things out!
But I think you're right - if you switch the iPad off (as opposed to simply putting it to sleep) the cache is cleared, as you suggested.
Can you tell me how to post or even reply to a thread?