Built-in Storage - Page 3

JmE · 09-03-03, 10:55 PM

Quote:

Originally posted by JakeRich
The Built-In is ROM, not RAM. RAM can be written and re-written to millions of times. However, if you remove power from RAM, it resets to null, no memory, all data is gone. ROM, on the other hand holds that memory even when the power is removed, which makes it ideal to hold the operating system, but that durability comes at a price--it's much harder to write to and therefore cannot take the stress of being written so many times. The net affect is that ROM is rated for about 10,000 writes. What that means is that most of hte chips will last that long, with a small percentage failing earlier. Most will last longer, but every cycle past 10,000 is going to get you closer to failure.

Working backwards, if you write to ROM 14 times a day, you'll be at 10,000 in two years. There is no guarantee that on the 10,000th write it will fail, but the probability starts to climb at that point pretty steeply. BTW, it's not a ROM address that will fail, but the whole ROM writing process.

The result is, then, that you can use ROM for storage as much as you want, but I would avoid putting highly volatile files there that get changed often. Backups are fine, plus the restore software. That's how I use it. But avoid putting journals, email, web pages, anything with high volatility on that memory.

Good info, but it is more like 100,000 cycles (please read my post about 9 posts above)

-JmE-

JakeRich · 09-03-03, 11:02 PM

Quote:

Originally posted by JmE
Good info, but it is more like 100,000 cycles (please read my post about 9 posts above)

-JmE-

Good catch. I had read 10,000 on some literature from Dell. Must be a typo.

JmE · 09-03-03, 11:12 PM

Quote:

Originally posted by JakeRich
Good catch. I had read 10,000 on some literature from Dell. Must be a typo.

However, your description of why the FlashROM has limited write cycles and what type of data one might want to and not want to store there was excellent. :)

-JmE-

rfortune · 09-03-03, 11:13 PM

LOL - actually based on the quick checks I did this aft (see my post earlier) it is more like 300,000 to 1,000,000.

JmE · 09-03-03, 11:30 PM

Quote:

Originally posted by rfortune
LOL - actually based on the quick checks I did this aft (see my post earlier) it is more like 300,000 to 1,000,000.

I saw that, but did not see any links so I stuck with the Intel spec stuff. I would lean towards your post being more like the real world numbers, but I haven't searched nor read much about it on the web.

-JmE-

KnipKnup · 09-03-03, 11:31 PM

I'll do some research at work and post exactly what the differences are and what/why we can expect for writes. Stay tuned...

disposition · 09-04-03, 12:43 AM

So wait... just a quick question, as I have not bought a PDA yet:

Does contact information saved via outlook/internet explorer/etc. etc. store itself on the RAM? I'm assuming so, as it IS random access... but I just want to make sure as I don't want to write to my ROM that much, regardless. I'll most likely save all the programs I write to my PDA on my desktop, or another flash card. Contact information and such will also be backed up on the desktop, I think.

rai_dei · 09-04-03, 01:00 AM

Hmmm i sees...
So if the ROM fails then you will not be able to use the operating system? or just the built in memory part?

JmE · 09-04-03, 01:16 AM

Well, as I understand FlashROM, it is likely an all or nothing type of flash (like our ROM updates for the Axim) unless there is a formatted area and file structure (like Built in storage on the Axim or FlashPro on some PalmOS devices). With that said, I would venture a guess that once areas of FlashROM begin to fail on writing, you would lose the ability to do a complete, all or nothing flash. It might be possible to use the handheld for a while, but I would think writing to it would be not usable. That is unless whatever was handling the file structure of the formatted area could handle bad sections. Even then I think it would go in addressable sections which might include the whole chip??? So, I guess reading would be possible, but writing would be out of the question?

I really am just speculating.

-JmE-

09-04-03, 11:39 AM

My built-in storage is empty, but is only about 5MB.

Why is this?

I can't even fit a back up in it! My back up file is 8.8MB.

09-04-03, 12:06 PM

yeah, if you have the basic Ax, then you have no space and need to get a flash card.

Don't get the Sandisk SD card though. Steer clear of those.

And if you want to backup, you can do it from the active sync app on the computer. just go into (i believe) tools- backup/restore

it will make a backup file on your hard drive. and you can use your extra internal space for a cool theam and an mp3. =)

KnipKnup · 09-04-03, 08:02 PM

The OS is stored in ROM as WindowsXP is on your HD. The rest of the ROM is available as memory and is written similarly to writing to your HD. If the HD crashes, your PC won't boot. If your ROM crashes, most likely, you would see it as - ax won't power on, or ax won't 'boot up'. Power wouldn't be affected, but nothing could happen. Maybe there would be some beeps, lights, screen garble, etc. but it would not work for a while or a minute. As well, it is one area as your HD is one area, so if it failed, the ax fails and you call Dell for a replacement.

There may be some built-in logic or something like HD's that handle bad sectors, but from what I know about memory chips, once they fail, they fail. You may see it in dead pixels, corrupted files, etc - varying by how bad the fail is.

Hope that ain't all mis-information!

Saxfiend · 09-04-03, 08:20 PM

Quote:

Originally posted by AximAdmin

Don't get the Sandisk SD card though. Steer clear of those.

What SD card manufacturer do you recommend? And what are some of the best overall deals on SD and Compact Flash cards right now...

JmE · 09-04-03, 09:08 PM

Quote:

Originally posted by KnipKnup
The OS is stored in ROM as WindowsXP is on your HD. The rest of the ROM is available as memory and is written similarly to writing to your HD. If the HD crashes, your PC won't boot. If your ROM crashes, most likely, you would see it as - ax won't power on, or ax won't 'boot up'. Power wouldn't be affected, but nothing could happen. Maybe there would be some beeps, lights, screen garble, etc. but it would not work for a while or a minute. As well, it is one area as your HD is one area, so if it failed, the ax fails and you call Dell for a replacement.

There may be some built-in logic or something like HD's that handle bad sectors, but from what I know about memory chips, once they fail, they fail. You may see it in dead pixels, corrupted files, etc - varying by how bad the fail is.

Hope that ain't all mis-information!

The problem is that we are talking about write failure and not read failure. With the HD analogy, XP must be able to write to the HD. The Axim, on the other hand does not have to write to the FlashROM in order to boot. The question then becomes if write failure occurs, is the rest of FlashROM still readable.

Another problem with the HD analogy is the way individual bytes are addressed on the platters. FlashROM may not be addressed in the same fashion. It might be addressed as huge chunks or peices, or whatever, I really don't know.

Lastly, it depends on what sort of HD failure. If it is one small area, sometimes, the system can boot and the data can be moved (depending on where the data is and how big the problem is). Also if the HD spindle motor is messing up, a head is crashing, stuck head, or many other things, the analogy will fall apart.

-JmE-

KnipKnup · 09-05-03, 12:40 PM

-jme-
Good thoughts.
I did some research and here's the deal...
FlashROM is a grid of 'cells' that can be programmed with a charge - or 0. Once programmed, reading the cell is a matter of determining whether there is a charge or not, which is interpreted as a 1 or 0 and software takes care of the rest. By the nature of FlashROM, once programmed, it stays. Then it can be read over and over. However, the programming process can be reversed in blocks of 4K, 8K, etc. to erase chunks of the chip. These blocks are then free and useable for more writing. The programming process is destructive because it involves forcing electrons through a non-conductive material (hence trapping them). Each programming/erasing process affects this non-conductive material. This leads to the 'lifetime' property of FlashROM. The more the material is 'punched through', the more conductive it gets and the more physically damaged it gets. Based on the part (its physical makeup - materials and its layout - 4MB, 8MB, etc.) the lifetime varies from about 10000 to 100000 reads/writes.
Apart from its lifetime, it can also fail for vast other reasons.
Since both read and write events require voltage to individual cells and blocks, if the fail is a short or something affecting accessing the cells, the whole part fails. The 'cells' will still have their charge but getting to it is not easy and very not-worth-it (unless you stored the cure for cancer or the date of Dell's release for the patch to WM2k3!). I suppose you would have to somehow manually apply voltage to each block and read them in, then putting the pieces together like a puzzle - probably based on some index, also stored in the chip, just like a HD does. However, you are dealing with millions of 'cells' in a square quarter inch area, so I don't think it very feasable.
Bottom line, store the cure for cancer in your safety deposit box and spread many copies very fast.
Or do like Dell and say you don't have one!:D