Tech: SD cards.....?

Subject: BS: SD cards.....?
From: Big Al Whittle
Date: 27 May 19 - 09:48 AM

How do they get all that information onto a little card like that?

Subject: RE: BS: SD cards.....?
From: Stilly River Sage
Date: 27 May 19 - 11:29 AM

How do so many angels dance on the head of a pin?

Secure Digital includes five card families available in three different sizes. The five families are the original Standard-Capacity (SDSC), the High-Capacity (SDHC), the eXtended-Capacity (SDXC), the Ultra-Capacity (SDUC) and the SDIO, which combines input/output functions with data storage.[38][39][40] The three form factors are the original size, the mini size, and the micro size. Electrically passive adapters allow a smaller card to fit and function in a device built for a larger card. The SD card's small footprint is an ideal storage medium for smaller, thinner and more portable electronic devices.

See Wikipedia.

Subject: RE: BS: SD cards.....?
From: punkfolkrocker
Date: 27 May 19 - 12:19 PM

The data has all the air and water extracted by vacuum process
to massively reduce bulk and weight,
thus enabling it all to fit tightly in the tiny SD card...???

Subject: RE: BS: SD cards.....?
From: Stanron
Date: 27 May 19 - 12:23 PM

I've never heard such rubbish! You are both wrong.

It's Magic!

Subject: RE: BS: SD cards.....?
From: Jon Freeman
Date: 27 May 19 - 12:27 PM

I've not a clue but they keep finding ways to cram more into decreasing areas.

In the case of a SD card, I read they are made up of tiny transistors of a type called "Floating-gate". See Flash Memory

Subject: RE: BS: SD cards.....?
From: DMcG
Date: 27 May 19 - 12:32 PM

In the days of my youth I attended a lecture by IBM saying it was impossible in practice to make anything more compact than the then-current core memory because there was a limit to how fine you could make the three wires without making them too fragile.

Subject: RE: BS: SD cards.....?
From: Big Al Whittle
Date: 27 May 19 - 01:04 PM

I just remember those huge reels of Ampex tape....
so many of them, and so expensive!
how long ago was that...1980's?

Subject: RE: BS: SD cards.....?
From: Dave the Gnome
Date: 27 May 19 - 01:05 PM

Electrickery!

Subject: RE: BS: SD cards.....?
From: Joe Offer
Date: 27 May 19 - 02:04 PM

SD Cards? Couldn't live without them. My cameras depend on them (although I've found the ultra-fast cards work best). And my digital recorder uses them, too. They sometimes make me worry - what if the card gets corrupted and I lose all the photos from that trip to Italy? And what if I lost that tiny card with that unforgettable concert? But so far, I've had no disasters.
-Joe-

Subject: RE: BS: SD cards.....?
From: Stilly River Sage
Date: 27 May 19 - 02:58 PM

Knock wood, Joe! Knock wood!

Subject: RE: BS: SD cards.....?
From: Bee-dubya-ell
Date: 27 May 19 - 08:11 PM

It's really quite simple. Digital data is basically nothing but ones and zeros, right? Well, a one doesn't take up very much space because it's skinny. But a zero is fat. It has a big hole in it, which is a lot of wasted space. This problem was solved by the invention of the Zero Flattener. It squashes zeros until they look just like ones. They don't become ones, but they look just like ones. About four times as much data can be stored in the same amount of physical space when the zeros in the data are squashed flat.

Subject: RE: BS: SD cards.....?
From: Bill D
Date: 27 May 19 - 08:34 PM

Some very creative answers here.. ;>)

I did read that after they figured out how to put stuff in such a tiny space, it took awhile to figure out how to access it an get it out again. I 'think' someone won a special award for working it out. Does anyone know about this?

Subject: RE: BS: SD cards.....?
From: Stilly River Sage
Date: 27 May 19 - 10:57 PM

It was the Pul-it-out-izer prize, I believe, Bill.

Subject: RE: BS: SD cards.....?
From: DMcG
Date: 28 May 19 - 02:04 AM

I have only (knowingly!) met one high end conman aiming to take - at current prices - tens of millions out of companies. It was around 1980 and he had 'invented' a new storage device based on analog technology which therefore did not have the same limitations as digital. One 'cell', being analog, could hold as many 'digits' as you wished: instead of 1 and 0 it could hold, say, 1.101110111011. Consequently whichever company gained the exclusive rights to manufacture this held the monopoly on the entire storage demand for the world.

In principle this could work. In practice, it is limited by the ability of A/D and D/A converters and the need for perfect repeatability - read that previous number back as 1.101110111001 and you do not have effective storage.

Nevertheless, the cost of NOT winning these rights, if they really existed, was as crucial as the cost of winning them, so both the specialist press and a number of companies took it very seriously indeed. I was one of about a dozen people in my company charged with assessing whether there was anything in it - he would not allow anyone to actually see or use the device, of course.

Subject: RE: BS: SD cards.....?
From: EBarnacle
Date: 30 May 19 - 08:39 AM

Were you the boy who cried "He's naked?"

Subject: RE: BS: SD cards.....?
From: DMcG
Date: 30 May 19 - 11:58 AM

Retrospectively, I did admire his technique. He started by talking for around 90 minutes about a completely different device that was theoretically feasible and used it to pick off anyone who challenged him about that by embarrassing them. Having fallen at the 'possible" fence, they were less likely to stick their head up again for the real money making con.

Subject: RE: BS: SD cards.....?
From: Mr Red
Date: 30 May 19 - 04:52 PM

all storage media come with a 5 year caveat. After that you are on bonus time.

CD/DVD, Flash memory - Sticks/SD/SSD, tape/floppy/external HDD.

record-able CD/DVD uses up to 9 layers of chemicals some cyano. The laser that burns in mSecs at high temps is heat-work and at 25 degC over can years be subject to the same heat-work. Don't leave on the dashboard of your car!

Flash memory usually is an embedded computer - it handles the USB/SD protocols and counts the re-writes to all blocks and when near the limit, swaps one out with a redundant unused block.

Magnetic layers suffer print-through and other fade mechanisms.

All are prey to alpha particles, satellite design has to cope with far higher hit rates. They are soft errors, but for archives that is academic .

And there has been a post from a Catter who had 10 external HDD and found 5 had suffered dropped bits after 5 years. Even though the data had been duplicated, some data were lost.

The way they cram more and more into Flash is by miniaturising the elements (OK transistors). And the error rates go up as the number of molecules used in each element fall (to a current 100ish), so they have to have redundancy and error correcting codes. Using computing subsystems to handle the cleverness.

Next up is DNA storage. That can store even more and in 3D. Currently slow read and write times. And Write Once. But - watch this space.

Subject: RE: BS: SD cards.....?
From: Stilly River Sage
Date: 14 Feb 23 - 10:44 AM

I came across an interesting article this morning that belongs right here.

What do all those microSD and SD card numbers and letters mean?
Deciphering microSD card and SD card storage jargon.

There are two commonly used storage media that people with Android phones, digital cameras or drones might be aware of -- these are the SD card and microSD card.

At first blush it might seem that all SD cards and microSD cards are the same, but a closer will show that they are not.

If you look at the front of any SD or microSD card, you'll see a whole bunch of symbols and specs, and being able to decipher these will tell you a lot about the card's performance.

After some more text and helpful illustrations, comes this:

OK, so after all this, the question is what cards should you buy?

First off, always buy a name-brand card from a reputable seller. Not only are there a lot of cheapo no-name cards out there, but there are also a lot of counterfeit knockoffs.

If you need a microSD card for a smartphone, then at the minimum it needs to conform to the A2 rating. However, I would buy a card that conforms to both XC I and the U3 UHS speed class.

I usually buy a new micro-SD card for any new phone I put into service, but at this point in time my phone won't take one. I have a number of other devices that use SD cards (small cameras, mostly) and should probably take a look at what is installed in each.

For those of you videoing performances with smart phones, this should be helpful to know.

Subject: RE: BS: SD cards.....?
From: Nigel Parsons
Date: 15 Feb 23 - 04:16 PM

There were these seven men of diminutive stature who explained it to me:
"IO IO IOIOIO!"

Subject: RE: Tech: SD cards.....?
From: Joe Offer
Date: 16 Feb 23 - 12:36 AM

If I'm playing music in my car, I find the best medium is a flash drive. I can easily load a hundred mp3 albums on a flash drive. But I'm looking for cost-effective ways to mail music to people, and postage rates are getting higher and higher. SD cards seem like a perfect way to mail music. I figure the recipient can transfer the mp3 files to a computer or flash drive, and then they wouldn't have to fumble with a tiny SD card while they're playing music.