# Micro SD Memory Card

**URL:** <https://boards.straightdope.com/t/micro-sd-memory-card/482621>\
**Category:** Factual Questions\
**Created:** [January 23, 2009, 12:21pm UTC](https://boards.straightdope.com/t/micro-sd-memory-card/482621 "2009-01-23T12:21:58Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Simple\_Mind](https://avatars.discourse-cdn.com/v4/letter/s/7cd45c/32.png) [@Simple\_Mind](https://boards.straightdope.com/u/Simple_Mind)\
**Post date:** [January 23, 2009, 12:21pm UTC](https://boards.straightdope.com/t/micro-sd-memory-card/482621/1 "2009-01-23T12:21:58Z")

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I just bought a 4Gb Micro SD Memory Card for my Mobile Phone, what makes me wonder is, how do they do it, i mean what kind of technologie are we using today to get so much storage capacity onto a piece of silicon(?) the size of 10x20x1mm.  
With my first Computer a Apple 2e, i was using large floppy Disks and with my present PC i still have my 1.44Mb Floppy Drive but what happened that we now have this new kind of storage for data, please somebody give me an easy to understand explanation.

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**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\
**Post date:** [January 23, 2009, 12:56pm UTC](https://boards.straightdope.com/t/micro-sd-memory-card/482621/2 "2009-01-23T12:56:04Z")

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Memory cards today are almost all built on flash memory technology - so yes, they are silicon chips for the most part. A flash memory cell is a particular arrangement of transistors that will ‘remember’ a 1 or a 0 for a very long time under ordinary circumstances, but can be ‘flashed’ to a new setting by a particular pattern of electrical voltage.

There’s nothing that really makes flash memory particularly more compact than magnetic technology like old floppy drives or modern hard drives - they can be accessed without moving parts, which helps, but mostly, the miniaturization of storage devices is just a case of practice and trying really hard - in other words, Moore’s law. 🙂

It boggles my mind too - that a memory card that can fit on one of my fingernails probably has more transistors built into it than there are people living on planet Earth today.