New answers tagged computer-architecture
1
By looking at a ASCII table you can see that the $4$ least significant bits of all characters between $0$ and $9$ correspond to the respective integer representations of the numbers between $0$ and $9$, while the 4 most significant bits are always $0011$.
If $x$ is the binary representation of a number between $0$ and $9$, you can then obtain the ASCII ...
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The von Neumann architecture was built for sequential computing. It was groundbreaking because it combined the instructions in memory along with the data for the instructions in the same space. Before this, programming required rewiring because each machine was built with a specific purpose in mind.
The essential idea is abstraction on some level. The ...
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Each element in that data path is purely logical, thus in each cycle an element can perform only a single operation.
If you had only one memory element, you would've possibly need to perform two operations in one cycle: (1) read the instruction (2) read/write data. This is impossible with a logic-only (sateless) elements within a single cycle.
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It is true that in more modern computer architectures, 8 bits is roughly synonymous with a single byte. However that doesn't always mean that we count things in bytes.
Think about a soft drink, maybe a Coca-Cola or something. What are some typical sizes it might be sold in? I will use my memory of Japan and the US as examples:
Japan: US:
375 mL ~ ...
2
There is nothing special about RAM. Before electronic computers were invented, mechanical data sorters and tabulators used punched cards as their main (and only) memory. Early electronic computers used many different technologies for their main memory, including vacuum tubes, acoustic delay lines filled with mercury, the screen of a cathode ray tube and tiny ...
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"Back in the day" computers were defined more by their word size, for example the PDP-8 had 12-bit words composed of two 6-bit "bytes". A "nibble" was half a byte, or 3 bits in this case (and here the op codes were 3 bits).
It is only in recent decades that 8-bit bytes became so prevalent as to make them the default.
Calling the NES 8-bit is less ambiguous ...
44
A) Historically, machines have been characterized by number of bits per 'machine word'. Why should NES be handled differently?
B) Calling it a 'byte' is not as clear since historically a 'byte' has not always been composed of eight bits (e.g some early machines had six bits per byte). Admittedly this is not so strong a point anymore.
C) On a side note: I ...
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The four segments you mentioned are not static - these are in fact registers that can point to any 64kb zone in the 1MB memory. By changing the value of these registers we can point to other fragments of the memory.
The exact computation of the effective address is performed using 2 registers: a segment register (CS,DS,SS,ES) and an offset register (usually ...
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The leftmost four bits of a segment register are used to extend 16-bit memory addresses, yielding 20-bit addresses. $2^{20}$ bytes is 1 MB.
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$\def\N#1{{\left[\text{#1}\right]}}$tl;dr– There're only 3 possible gates that satisfy these properties:
depend on both of 2 binary inputs to produce 1 binary output;
don't discriminate between the inputs;
aren't just another gate $\texttt{NOT}\text{'d} .$
These 3 gates are usually described as $\texttt{AND} ,$ $\texttt{OR} ,$ and $\texttt{XOR}$ as ...
1
AND
I like red AND ripe apples.
If the apple is red and the apple is ripe, then the result is true
1 and 1 makes 1 (true)
The apple is green, so I don't like it
0 and 1 makes 0 (false)
The apple is red but not ripe
1 and 0 makes 0 (false)
OR
I'll eat an apple if it's ripe OR if it's red
The apple is red, but not ripe so I'll eat it
1 or 0 makes 1 (...
9
The why of it actually comes from the development of logic, which is a philosophical study of what is true and what is not true. Logic was originally a study of human language with the assumption that if you can reason about how human language works you can maybe reason about how reason works.
Since the language I'm answering you in English let's use ...
0
Is it a conditional definition for example?
Yeah, that's a good way to look at it.
One way of writing the definition of the AND operator is:
The AND operator is that operator that takes two bits as input and gives one bit as output, such that
0 AND 0 = 0;
0 AND 1 = 0;
1 AND 0 = 0;
1 AND 1 = 1.
Likewise, one way of writing the ...
1
I interpret question 'why' as asking for the purpose.
So imagine OR, AND and NOT as the simplest building blocks from which you can build almost anything else. (Just remember it as some kind of simplification: NAND gate seems to be more universal and simpler from electronic engineering point of view but is less intuitive for learning purposes)
As an ...
77
As stated by user120366, 16 possible 2-input logic gates exist, I've tabulated them for you here:
A|B||0|1|2|3|4|5|6|7|8|9|a|b|c|d|e|f
-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
0|0||0|0|0|0|0|0|0|0|1|1|1|1|1|1|1|1
0|1||0|0|0|0|1|1|1|1|0|0|0|0|1|1|1|1
1|0||0|0|1|1|0|0|1|1|0|0|1|1|0|0|1|1
1|1||0|1|0|1|0|1|0|1|0|1|0|1|0|1|0|1
A and B are the inputs, 0 through f ...
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You can look at it as two stages.
The first stage is that we want some particular outcome, such as wanting a 1 if either of the (2) inputs is a 1. We call this an “OR” gate. Another outcome that people want is to get a 1 only if both inputs are a 1. We call this an AND gate.
The final stage is that we want a particular gate for every possible ...
1
To answer this, I think it is best to go back to those early 'Truth Tables' you probably saw in algebra. The first ones you see are 'and' & 'or'. We have two statements #1 & #2 (usually called p & q) which can either be true or false. Then, when we test them we have a result (usually called r).
For example,
#1 p = I like red
#2 q = I like dogs
...
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I think the questioner has it backwards. If we have a logical function such that
A | B | result
---+---+-------
0 | 0 | 0
0 | 1 | 0
1 | 0 | 0
1 | 1 | 1
then we decide to call that function and because it is obvious that the result is 1 only when A and B are both 1.
Similarly for or, exclusive-or, etc.
There are 16 ...
3
The boolean operators (and, or) are functions that map two inputs to an output, just like any other binary operator (i.e. +). Their exact behavior (the why question) is an axiom of boolean logic, just as the behavior of addition is an axiom of mathematics, which is to say that we agree that these operators do what they do. It is therefore the bedrock of ...
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It's easiest to think of $1$ representing a true statement and $0$ representing a false statement. The logic gates then act as truth functions.
Say you put two statements, $p,q$, together to form a new statement, $r$.
In the case of and (logical conjunction), both $p$ and $q$ must be true for $r$ to be true. In the case of or (logical disjunction), $r$ ...
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