DNA is a long molecular chain. This chain is made of two halves that run along side each other and are linked to each other, like hotdog buns. Each half is known as RNA, which itself is a long chain of molecular units. Each molecular unit is a nucleotide, and each nucleotide has as base that is either adenine, thymine, cytosine, or guanine. Along the length of the chain any nucleotide can bind to any other nucleotide, but between chains of RNA only certain bases can bond. Adenine can only bond to thymine and via versa. Cytosine can only bond to guanine and visa versa.
When DNA is being sequenced, only one half (one strand of RNA) is used. Because there's a single pairwise connection between nucleotides (square peg goes in square hole, round peg goes in round hole) reading one half tells you the other half. This means you can represent the entire strand of DNA by only using half of it, the RNA. Sequencing DNA is where you get to the point where you record the sequence of nucleotide bases. The bases are abbreviated to A, T, C and G, and that's what's shown on the screen.
In real life full genome sequencing (to the point you can list the nucleotide bases as letters) is an expensive and lengthy process. The kind of DNA analysis that is used in forensic analysis or for ancestry doesn't go down that far. For that much less expensive analysis tools such as blotting, variable number tandem repeat, amplified fragment length polymorphism, or others are used. You don't get the base to base sequence out of these techniques, but the results are enough to get a "DNA fingerprint" of a person or animal which for forensics is all you need.
Computer code on some level
is 0's and 1's, or binary, but it's rarely (that is, almost never) read like that. 1's and 0's themselves are an abstraction for "On" and "Off" which themselves are an abstraction for "high" and "low". "High" being a high enough voltage to excite a transistor and cause it to activate, and low being the point in the opposite direction where that doesn't happen. Because binary is already an abstraction, when machine code or the raw representation of data is being represented on a screen it's usually in hexadecimal (base 16) because that is much more compact and legible than binary.
Sidenote, we use base 10 (decimal) in everyday life, that is 0 to 9, and when counting past 9 we put a 1 in the ten's place. Binary has 0 and 1, so counting past one you put a 1 in the two's place. Hexadecimal goes from 0 to F, (0123456789ABCDEF) and counting past F you put a 1 in the sixteen's place.
Base 16 is generally easy to convert to and from with binary. That's because binary values can be divided into nibbles of data (4 numbers in a sequence, either 0's or 1's) that corresponds to a single base 16 digit.
Here's a table that shows various representations of numbers. The binary is broken up with spaces between nibbles. Yes, nibble is the technical term.
| Decimal | Binary | Hexadecimal |
| 8 | 1000 | 8 |
| 11 | 1011 | B |
| 139 | 1000 1011 | 8B |
You can see on the last row how the binary representation is just the previous two numbers put side by side, which mirrors the hexadecimal representation. This isn't the case with the decimal representation. You can memorize the binary representation of hexadecimal digits and read any binary number into hexadecimal and visa versa easily, but that's not the case with binary.
Computer code written by an actual programmer is usually abstracted further than hexadecimal into something much more human readable, assembly. Assembly itself is abstracted even further to programming languages. You can brows Github if you want to see what those look like. Programming languages are tools that programmers can use to make use of higher level concepts without worrying so much about the implementation that encounters silicon. Programming languages are then translated (compiled) into a form that the hardware can read, except when they're not (as in the case of interpreted languages, or languages that run on a virtual machine). As much as I would love to get into how all of these work and the nitty gritty of an ALU I've taken up enough of your time already.
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