Hello panck4beer,

thank you for your rapid answer and explanation. You mentioning of "change address" made me google and I found https://en.bitcoin.it/wiki/Change

Right at the end of that page is the paragraph "The wallet file contains the private keys for change addresses, and they can receive and send coins normally. However, the GUI in the default client does not display them in the address book."

Case solved - that is my explanation.

BR
Max.

Hello Everybody,

could somebody please help me understand ?

I have a slight difference between the total balance shown in bitcoin-qt and blockchain.info.

My balance shown in bitcoin-qt is 15.32232057 BTC, my local copy of the blockchain is up to date (block 271912).

My balance shown on blockchain info is 15.31140586 BTC
https://blockchain.info/address/1B3g1eZxAvCiHPJh7NbT1y4fJiLn2SqsUL

The difference is 0,01091471 BTC

Last night I did a transfer to my mobile of 0,1 BTC.
https://blockchain.info/de/tx/f2d6c45a72e75f99842de460c59d1ba12d3adb39aecdd9cf37fbd9de3ca9f6b4

The 0,1 BTC arrived on my mobile.

However the transaction f2d6c45a72e75f99842de460c59d1ba12d3adb39aecdd9cf37fbd9de3ca9f6b4 (which did send the 0,1 BTC to my mobile) also did send to 1JJQ7s6kLX46FjAcsHNejGADVT6GMHne8n the amount of 0.01091471 BTC. Which is exactly the difference between what my local bitcoin-qt and blockchain.info show for my wallet. 1JJQ7s6kLX46FjAcsHNejGADVT6GMHne8n is not any address of mine.

Both the bitcoin-qt which comes from the ppa https://launchpad.net/~bitcoin/+archive/bitcoin as well as the compiled 64 bits binary from https://launchpad.net/~bitcoin/+archive/bitcoin show the balance of 15.32232057 BTC ( i.e the slightly higher amount ). I verified the sha256 hash for the bitcoin-qt from sourceforge.

I have set zero transaction fees in bitcoin-qt.

bitcoin-qt version v0.8.5.0-gef14a26-beta in the ppa version of bitcoin-qt. Version v0.8.5-beta of bitcoin-qt from sourceforge.

So why ? I do not understand the difference and not understanding makes be feel uneasy.

Thanks
BR
Max.

Yes, but for this application the LX150T is not needed. The T at the end is for a quite fast transceiver which is great when you want to connect to fast periphery.

For this application a Spartan 6 LX150 is right. Preferably multiple ones on one pcb.

However the LX150 is available only in BGA or CSP, which you cannot solder yourself. You'll need an oven for that. And maybe a stencil for the solder paste too if it's not a prototype. Also BGA package means that you need a multilayer pcb.

What I want to say is that it's certainly not impractical, but you'll not going to engineer this on a weekend.

The way I understand Xilinx' ug389.pdf data sheet you appear to just refer to the pre-adder, which is indeed 18 bits + 18 bits.

However the post-adder is 48 bits wide. Do have a look at ug389.pdf, especially p. 10 , figure 1-1 and 1-2.

You see the inputs a, b and d, which are 18 bits each. They can be concatenated with opcode[1:0] set to 11. Then set opcode[3:2] to 11 to select input c as the other input source of the post-adder.
Finally please see p. 22, table 1-7 and have a look at the 5th entry from the end. The eq. describing the output of the dsp48 is given there as: P = C ± (D:A:B + CIN)

That should do nicely to speed up the adder at the end of each sha256 round.

If you could compare your design's performace with and without the use of the dsp48a1 slice and share the resulting specs, then that would certainly satisfy my curiosity

Are you aware of articles like this one, which suggest ways to improve the implementations, or did you use the opencore or write your own ?
http://ce.et.tudelft.nl/publicationfiles/1194_657_SHA2.pdf
http://ce.et.tudelft.nl/publicationfiles/1194_657_springer-SHA-2.pdf
http://ce.et.tudelft.nl/publicationfiles/1429_657_04560238.pdf

Regarding a devel board with a Xilinx Spartan-6

There is a massive fpga compute board here:
http://www.dinigroup.com/new/DNBFC_S12_PCIe.html
I don't know what it costs though, but I doubt that it'll come at a bargain price.
The 2 gb ram per fpga is not needed for computing sha256 hashes.

There is a devel board from Avnet
http://www.em.avnet.com/ctf_shared/evk/df2df2usa/xlx-s6-lx150t-dev-pb122409.pdf
http://www.silica.com/products/highlight/product/xilinxR-spartanR-6-lx150t-development-kit.html
No idea about availability. Price stated in the PDF and website is USD 995,-

A devel board with a LX150 ? I was only aware of the Digilent Atlys Spartan-6 with a LX45 for about 140 EUR. From which company do you source it ?
Google found a PCIe card from Enterpoint in the UK with a XC6SLX150T for £480.00 tax excl, a bit much for a devel board.

Having read through the post concerning bitcoin mining with fpgas here I wonder whether the DSP48A1 slice in the newer Spartan-6 can be put to good use, since it has a nice adder.

Seems that I must pull out my old Spartan 3E devel board to have a better look. But that doesn't have dsp slices. Darn.