Quote from: Peter R on May 02, 2014, 12:53:10 AM

Quote from: Soros Shorts on May 01, 2014, 11:47:47 PM

Quote from: telepatheic on May 01, 2014, 11:34:02 PM

Quote

bitcoin QT can sometimes use upwards of 1 GB of RAM.

With some custom settings to limit what gets held in memory, you could get this down to less than 10MB, but it would require a fair bit of work.

Whatever work is done must not slow down the speed at which the node works. You would be doing the network a disservice if your node took a long time to validate and relay messages and blocks because of your low memory footprint and under-powered CPU configuration.

I think people underestimate how powerful low-cost DSPs have become. For example, C. Gouvea was able to verify secp256k1 ECDSA signatures in 700 ms using an ultra-lower power 16-bit microcontroller running at a only 8 MHz (and available as in a tiny 3 x 3 mm package size). Even very cheap ARM-core processors ($2 - $4) will typically run at ~150 MHz (and with 32-bit registers). So let's say signature verification for each received TX takes no more than 20 ms, at which point you can relay the transaction to your other peers. This seems perfectly acceptable to me.

The only other issue I can think of is RAM, but I don't see why you can't store the unspent outputs in the SD card itself (new SD cards permit reads in excess of 30 MB/s so I think the time it takes to cross check the outputs in a TX with the blockchain unspent outputs stored in flash will be short compared to the signature verification times [20 ms]). It seems you just need sufficient RAM to pool the unconfirmed transactions (and some overhead to accept new blocks, etc), so upon first glance the 6x8mm 64 MB IC for $1.50 seems sufficient for this purpose.

I think such a bitcoin node would be useful if it could be made only a few cm in dimensions, cost less than $10-$15 excluding the SD card, and be trivial to set-up.

I think write endurance would be an issue if you're trying to use an SD card as RAM.