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[Merged] iPad RAM / multi-tasking thoughts / etc

AppleMary said:
Only 512 Megs folks--that might be enough in the year 2000, but not today. So don't expect them to add multitasking to this generation.
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There may be some truth in what you say. I have "Desktop". Nice concept and useful mini apps but when I try to run more than one I get out of memory messages. Now, I'm beginning to see why Apple wants to pull those "Desktop" multi tasking apps from the App Store.
 
AbsurdGenius said:
Have been reading a few threads about the debated iPad RAM and came across this on iFixit when i googled it.

"Decoding the part number shows there is 2Gb of memory inside. This translates into ~128MB of memory per die, for 256 MB total. (NOT 512MB, as we previously reported.)"

http://www.ifixit.com/Teardown/iPad-Teardown/2183/2
:(
Click to expand...

Yeah looks like they were wrong, and changed it. I don't know what Apple is thinking only putting 256MB of RAM in that's shared into a device that has a 1024x768 screen. :(
 
Justinf79 said:
Yeah looks like they were wrong, and changed it. I don't know what Apple is thinking only putting 256MB of RAM in that's shared into a device that has a 1024x768 screen. :(
Click to expand...

Apple is thinking how the same people will pay them again for iPad v2 in about a year. Why do you think Apple has such high profits? Because of good products? You wish.
 
It seems that there is 512MB RAM but apps can only see 256 available. Chances are that the other 256MB is solely for the OS which will allow it to retain it's speed.
 
iFixit has posted a correction. According to them now there are two 1-gigabit chips, 128-megabytes each, for a total of 256 megabytes.
 
I'm a bit confused, does the iPad have 256MB RAM in total, or is it that only 256MB are accessible by apps, while the other 256MB is dedicated to the OS or video memory?
 
Apple should have asked macrumors members how much ram to build into the iPad because clearly they have no idea how to engineer computers and mobile devices!
 
ImperialX said:
I'm a bit confused, does the iPad have 256MB RAM in total, or is it that only 256MB are accessible by apps, while the other 256MB is dedicated to the OS or video memory?
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The iPad definitely has 256 MB of RAM total. Not all of that is accessible to devs, though. iFixit has now stated that they've only found 256 MB in their tear down, and my own testing corroborates this:

csnplt said:
For those of you that care, I can confirm that, at least according to BSD, the iPad has 256 MB of RAM.

If anyone wants to verify this, here's the objective-c function to try this with the iPhone SDK:
Code: 
//Returns bytes of RAM
int getRamSize()
{

	int     count ;
	size_t  size=sizeof(count) ;
	
	if (sysctlbyname("hw.memsize",&count,&size,NULL,0)) return 1;
	
	return count;
}

I'm a bit surprised that this amount is so small, but so far at least, it doesn't seem to affect performance much (the iPad is still very fast). This is the same amount as the third gen iPod touch and the iPhone 3GS. Maybe we'll see more of an impact if and when there's official iPad multitasking.

Synthetic Benchmarks:

Also, using a benchmark I wrote called Gauge Mathematical Tool, the iPad scores 380 points or so, compared to a score of 190 on my iPhone 3GS. It should be about twice as fast for apps that are intensive for the CPU.

Meanwhile, it takes about 4 seconds to find 50,000 digits of Pi on my iPad and 8.24 on my iPod touch 3G. This also shows a 2x speed improvement.

This makes sense, I think, as the iPad's A4 CPU frequency is almost twice as high as that of the iPod touch 3G or iPhone 3GS, and likely also benefits from tweaks to the architecture.

You can read more about how Gauge Mathematical Tool works internally at my website, thomashuntington.com, but it's a pretty good general use benchmark that is CPU, RAM, and Graphics intensive, available for all iPhone OS Devices in the App Store here.

Thomas Huntington
iPhone and iPad Developer
Click to expand...
 
ImperialX said:
I'm a bit confused, does the iPad have 256MB RAM in total, or is it that only 256MB are accessible by apps, while the other 256MB is dedicated to the OS or video memory?
Click to expand...

We're all confused. At first I thought I was right, then wrong, and now right again. Either way there is no way that there would be no heavily rumored multitasking on the OS 4.0 update without the iPad being able to handle it.

I would hope Apple knows what they're doing. As of right now I'll hold back on purchasing an iPad until I see how it performs under multitasking.
 
Honestly i'd be happy with two modes of the "multitasking", one is the frozen app model which is where the state of the application is preserved as the user switch to another application, which still makes it mono tasking but with the illusion of multitasking. The other one is a special protected and verifed by apple background service for music and such apps to be running at same time, it can even just use Apple's iPod apis.

As of right now, most applications don't return to the same state when the user switch to that app.
 
csnplt said:
The iPad definitely has 256 MB of RAM total. Not all of that is accessible to devs, though. iFixit has now stated that they've only found 256 MB in their tear down, and my own testing corroborates this.
Click to expand...

Thank you for your detailed analysis, it really helped. However I'm still confused about the video memory. Is the video memory going to be taken out of this 256MB of RAM, or does it have its own memory?
 
ImperialX said:
Thank you for your detailed analysis, it really helped. However I'm still confused about the video memory. Is the video memory going to be taken out of this 256MB of RAM, or does it have its own memory?
Click to expand...

I'm pretty sure that it's shared with the main memory. That means that actual free RAM will probably be even lower. The same functions I wrote about before also report a "user memory" amount of 200 MB or so, which I assume takes account of any memory that's reserved for the graphics, and lower level hardware. I'm by no means an expert in ARM SOCs, though. Here's a very informative review of the iPhone 3GS at Anandtech, which goes much more into depth: http://www.anandtech.com/show/2782

A lot of what Anand says about the iPhone 3GS should also apply to the iPad.
 
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