How a memory works - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: October 21, 2014, 01:47:08 am
content: Hey guysive been wondering, how a memory work? i mean, physically, what makes inside of it that saves data or something?

author: Kdog44
author_rank: Contributor
timestamp: October 21, 2014, 01:53:30 am
content: what type of memory are you talking about? RAM, ROM EEPROM .. etc

author: atferrari
author_rank: Frequent Contributor
timestamp: October 21, 2014, 02:02:45 am
content: Quote from: little_carlos on October 21, 2014, 01:47:08 amGeneric questions like yours are better served if you go straight to a complete article or tutorial amongst the so many you could find in the Web.Why not Google and then coming to the forum for details?

author: Falcon69
author_rank: Super Contributor
timestamp: October 21, 2014, 02:08:05 am
content: i'd say it has to do with millions of latched type circuits holding 1 or 0 inputs.like latching logic chips, flipflops, etc. am i close?

author: hamster_nz
author_rank: Super Contributor
timestamp: October 21, 2014, 02:16:13 am
content: Quote from: little_carlos on October 21, 2014, 01:47:08 amThe link a helpful person would give you ishttp://www.akkadia.org/drepper/cpumemory.pdf- "What Every Programmer Should Know About Memory". 114 pages, very dense in information. Read until you head explodes, the read it againSection 2.1 has most if the information you are after.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 21, 2014, 02:26:13 am
content: Quote from: Falcon69 on October 21, 2014, 02:08:05 amYes, for SRAM. But there are heaps of other technologies.For most DRAM it is little leaky capacitors, holding charge while they are regularly topped up by refresh cycles.For Flash it is a static charge/electrons that have tunnelled themselves into a little pocket above a FET junction, holding the gate open or closed.For ROM it can be constructed that way, with metal connections on the silicon chip that encode what data will be read back.For PROMS it might just be fuses that are blown when it is programmed.There there is phase change memory and a whole lot of other exotic stuff like core memory

author: tggzzz
author_rank: Super Contributor
timestamp: October 21, 2014, 08:56:33 am
content: Quote from: hamster_nz on October 21, 2014, 02:26:13 amDon't forget mercury delay lines, core memory, bubble memory, or even moonbounce

author: macboy
author_rank: Super Contributor
timestamp: October 21, 2014, 03:08:16 pm
content: Quote from: hamster_nz on October 21, 2014, 02:26:13 amCore memory is hardly "exotic", as it was one of the first ever electronic memory technologies.Quote from: little_carlos on October 21, 2014, 01:47:08 amI mean no offense, but haven't you ever heard of Wikipedia? It has excellent articles on all common (and uncommon) memory types, including principles of operation in relatively layman terms.http://en.wikipedia.org/wiki/Computer_memory

author: Simon123
author_rank: Regular Contributor
timestamp: October 21, 2014, 03:18:33 pm
content: There is also memristor.http://arstechnica.com/information-technology/2014/06/hp-plans-to-launch-memristor-silicon-photonic-computer-within-the-decade/

author: Neilm
author_rank: Super Contributor
timestamp: October 21, 2014, 06:05:32 pm
content: Fram - magnetic memory that retains the information.

author: Rigby
author_rank: Super Contributor
timestamp: October 22, 2014, 10:11:49 pm
content: Simplecpu.com will get you a basic answer. Hope I am remembering that URL properly.Direct link to that page:http://simplecpu.com/memory.html

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 22, 2014, 11:20:20 pm
content: Quote from: tggzzz on October 21, 2014, 08:56:33 amIn the mid 1970s we made our own graphics terminals (because you couldn't buy one from anyone).We had to use a magnetostrictive delay line to get the speed and capacity to buffer enough info to refresh the screen.It looked like several turns of rather fine steel wire in a box about 12 inches square with an input and output transducer.Not completely unlike spring reverbs still found in vintage (and retro) guitar amps, etc.

author: coppice
author_rank: Super Contributor
timestamp: October 23, 2014, 07:16:02 am
content: Quote from: Richard Crowley on October 22, 2014, 11:20:20 pmDid you really mean the mid 70s? You seem to be describing mid 60s issues. By the mid 70s a number of graphics terminals were available, both complete terminals and modules for integration into consoles. I used quite a few of them. They didn't use delay lines either. DRAM was the normal buffer store by that time, for those which needed a buffer store. Storage tube graphics terminals, of course, did not require any form of buffer store.

author: tggzzz
author_rank: Super Contributor
timestamp: October 23, 2014, 08:31:40 am
content: Quote from: Richard Crowley on October 22, 2014, 11:20:20 pmInteresting. That vaguely rings a bell, but it might be one of my remaining neurons misfiring.What was the delay and bandwidth (or number of bits)? (I presume it wasn't analogue, since each trip around the loop would have added noise.)I'm mildly surprised there was little (no?) attempt to keep the successive loops separated, so as to minimise crosstalk and ghosts. But that reveals my ignorance.I should also, of course, have mentioned Williams CRT memories.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 23, 2014, 02:27:55 pm
content: Quote from: coppice on October 23, 2014, 07:16:02 amYes, I believe you are correct. It was more like mid-late 60s now that you jog my memory.QuoteI have a vague recollection that it was several K bits.QuoteI believe the data was regenerated for each trip (not unlike refreshing DRAM).QuoteI thought the mechanical action was axially through the length of the wire, but I never investigated it. I wondered about the loose winding also. Note that there are some examples of the technology where the loops are held apart by "bearings" and brackets...

author: gxti
author_rank: Frequent Contributor
timestamp: October 23, 2014, 02:46:28 pm
content: Quote from: macboy on October 21, 2014, 03:08:16 pmAnd now it's quite dead, so I guess that makes it exotic again.Storage tubes are another fun one. Draw on a CRT, then read it back:https://en.wikipedia.org/wiki/Storage_tube

author: hamster_nz
author_rank: Super Contributor
timestamp: October 23, 2014, 08:00:59 pm
content: Quote from: macboy on October 21, 2014, 03:08:16 pmI wonder how much core memory has ever been produced? I'm would bet that I have more memory in my cell phone (272 Gbits, flash+RAM)...Mike