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What Can You Do with Old Memory?
An anonymous reader asks: "I've just upgraded the RAM in a bunch of laptops and have several gigs of spare PC2700 memory sitting in a desk drawer. I also have another project which requires a large amount of low latency temporary storage. So, I figured this would be a great place to employ a dedicated hardware ramdisk but I am having a problem finding one that doesn't cost an arm and a leg, or preferably an empty unit that works with my spare memory. I have found many discussion forums which talk about building an IDE ramdisk out of commodity RAM, but have not found anyone that has actually done it. Has anyone on Slashdot found such a holy grail? Is anyone currently working on such a project? Do any of you have the engineering experience and interest to design such a device?" What novel purposes have you done with spare RAM that you haven't had the heart to throw away?
"Before you ask, my primary server is maxed out on RAM at 2 gigs, and I am still filling up my 1 gig software ramdisk when I end up with an unusually large data set that needs processing. Yes, I am aware that an IDE device would be limited by the IDE interface for throughput, but I am more concerned with latency then throughput, and IDE is common and simple enough to connect to any of my desktop servers without the need for an add in card."
The older SIMM modules make excellent modules to add a big chunk of memory to your controller/processor/DSP/FPGA for all kinds of things.
Or you can just use a paintstripper and get the chips off, and incorporate them in your project.
The left over boards you can use as guides in your tech books.
Interfacing can be tough sometime, here an AVR example:
http://www.myplace.nu/avr/dram/index.htm
Just google for your favorite controller type with the word DRAM.
they require identical chips- and usually aint cheap.
every day http://en.wikipedia.org/wiki/Special:Random
I concur, please do consider donating the memory. I worked for a local place that refurbished donated computers and used them for a community networking initiative which provided poor people with:
All of this was provided at no cost to the recipient. As I understand the financing, the place is run on a combination of grant money, selling dialup accounts and hosting, and donations. After building and testing a bunch of low-end machines used for these classes, my work there ended. It was a good karma job with good people working there and I would work there again if the need arose.
As a former technician there, I would have been grateful to receive donated RAM for what is today considered old. I'm sure someone's machine would have used it (or some machine that will soon be donated there would use it).
Digital Citizen
I've done this for a long time too. Someone noticed it and accused me of buying it at some nearby computer store. After informing said person that I am geek enough to make my own RAM keychain I was surprised at how much they were charging for these things. Don't think it's a get rich quick scheme but I've got to give it to them for marketing and obsolete product.
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And this is pissing me off. I need more memory for my PIII-800 (PC100 memory) and it's cheaper to buy memory for my laptop that I got back in the summer!
SRAM (Static) actually keeps it's state when you power it off
No. SRAM keeps its state as long as it's still powered. DRAM is in a state of continual decay, and must be refreshed on a regular basis.
And to further add to the confusion, NVRAM (non-volatile) RAM stays put without power.
"Nature doesn't care how smart you are. You can still be wrong." - Richard Feynman
Wait, is someone pulling numbers out of their ass?
+- $25 total time: 3hrs - 2months depending on expiriance
Except for the fact that your PIC probably has 16 or so data lines, and you need 100 or so addressable lines to talk nicely to PC2700 ram. Oh, and don't forget the 40 lines you need to talk to the IDE interface.
So , that $25 just ballooned out to a coupla hundred when you factor in some glue logic and a few fpga devices of sufficent capacity. And 3 hours might be a little on the low side there for the labour estimate.
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
http://www.hyperos2002.com/07042003/products.htm
HyperOs HyperDrive III, 16GB capacity, ATA100, rather pricey.
http://www.cenatek.com/
Cenatek Rocket Drive, various product versions, PCI instead.
Freecycle is a neat community giveaway-fest run through localized Yahoo groups. I live in a town of 100,000 and the Freecycle group has 700 members. I've given away old monitors, tables, couches, even a car. I got a nice little dual-proc server. Right now I'm paring down what I have for an upcoming move, but it's a great place to get free stuff. I see bedframes, dressers, computers, bikes, clothes, it makes dumpster-diving obsolete.
No. There are three main types of RAM:
SRAM (Static) will keep its state as long as it is powered on.
DRAM (Dynamic) will lose its state, and must be regularly refreshed as long as it is powered on.
NVRAM (Non-volatile) keeps its state even when powered off.