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en:ztex_boards:ztex_fpga_boards:litcoin_mining_on_fpga [2013/07/15 17:57] – [Approach 2: FPGA implementation using external RAM] 84.181.59.227 | en:ztex_boards:ztex_fpga_boards:litcoin_mining_on_fpga [2017/01/21 14:25] – [Approach 2: FPGA implementation using external RAM] stefan | ||
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* The PBKDF2-HMAC-SHA-256 function can be neglected here. The computations can be done parallelly to the other computations and a single 64 cycle per SHA256 transformation loop is sufficient for many scryptROMix loops | * The PBKDF2-HMAC-SHA-256 function can be neglected here. The computations can be done parallelly to the other computations and a single 64 cycle per SHA256 transformation loop is sufficient for many scryptROMix loops | ||
* Due to decencies of intermediate results each scryptROMix loop requires about 140,000 computation steps | * Due to decencies of intermediate results each scryptROMix loop requires about 140,000 computation steps | ||
- | * Each scryptROMix loop (or pipeline stage) requires one 128 KByte vector (which has to be stored in some kind of RAM) | + | * Each scryptROMix loop (or pipeline stage) requires one 128.125 KByte vector (which has to be stored in some kind of RAM) |
===== Approach 1: FPGA implementation using Block RAM ===== | ===== Approach 1: FPGA implementation using Block RAM ===== | ||
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On XC6SLX150 n is 4 and estimated f is 300MHz. **Hash rate would be approximately 8.6 KH/s.** | On XC6SLX150 n is 4 and estimated f is 300MHz. **Hash rate would be approximately 8.6 KH/s.** | ||
- | ===== Approach 2: FPGA implementation using external RAM ===== | ||
- | One implementation approach would be fully unrolling the scryptBlockMix function. This results in an 68 stage pipeline and approx. 8.7 MByte memory requirement. Pipeline clock is defined by the memory read / write delay. Altogether, hash rate is limited by memory bandwidth b: | ||
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- | b | ||
- | r = ---------- | ||
- | 262272 B/H | ||
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- | On [[http:// | ||
- | 61 kH/s. Due to latencies of DRAM **a hash rate of 50 Kh/s** are more realistic. | ||
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- | **In order to prevent confusions and questions: ZTEX does not plan to develop Litecoin mining software.** |