# Monthly Archives: April 2015

## Masking, bit-shifting and & 0xff00

By | April 29, 2015

If you are reading about endian (big and small) and seen snippets of code where you AND the input with 0xff00 and then shift the result say by 8 via >> 8 and wondering what the heck is going on then you’ve come to the right place. If you have an input such as int… Read More »

By | April 23, 2015

Understand how bitcoin mining works can seem like a huge task. They key is to break it down piece by piece. The first step is to understand what SHA256 is. Search on Google and read all you can about it. Then read this document: fips-180-4.pdf. The Federal Information Processing Standards Publication. Spend 2 weeks reading… Read More »

## What does upside down V and plus inside a circle mean?

By | April 19, 2015

If you have been looking at bitcoins and in particular the SHA256 algorithm, you would have come across this formula: Maj(x,y,z)=(x∧y)⊕(x∧z)⊕(y∧z) Ch(x,y,z)=(x∧y)⊕(¬x∧z) The first thing I said to myself was “What the heck does this mean? Do I need a PhD to understand this?” Well, the good news is that the meaning is pretty simple… Read More »

## What does the bitcoin target really mean – part 2

By | April 8, 2015

I’ve done a lot of reading trying to figure out what a bitcoin target really means and after reading over 10 different explainations, over several days, I think I finally understand. Here are some of the basics. 1. You’ll see people talk about the maximum target of: 0x00000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF. What the heck does this mean and… Read More »

## Real example of biased exponent of a number

By | April 6, 2015

After lots of Googling to try and understand what an exponent bias really means, I came across this video which explains it pretty well. When someone talks about biasing the exponent, it means trying to represent negative numbers with positive numbers so you don’t have to put a negative sign in front. It is just… Read More »

## What does hash lower than a bitcoin target mean with example – part 1

By | April 5, 2015

So you’ve Googled bitcoin target, read a whole bunch of stuff but still don’t get it and want to see real examples for comparisons. You’ve come to the right place. I learn best with examples so here goes. From Bitcoin wikipedia “The target is a 256-bit number (extremely large) that all Bitcoin clients share. The… Read More »

## Ubuntu how to show contents of a package before installing?

By | April 3, 2015

If you want to know what files are going to be installed/placed on your computer when you download a package for Ubuntu, you can run this command: apt-file list package_name If you run this and get this error: The program ‘apt-file’ is currently not installed. You can install it by typing: sudo apt-get install apt-file,… Read More »