## Difference between 1 and 1'b1 in Verilog

What is the difference between just giving 1 and giving 1'b1 in verilog code?

The 1 is 32 bits wide, thus is the equivalent of `32'b00000000_00000000_00000000_00000001`

The 1'b1 is one bit wide.

There are several places where you should be aware of the difference in length but the one most likely to catch you out is in concatenations. `{}`

reg [ 7:0] A; reg [ 8:0] B; assign A = 8'b10100101; assign B = {1'b1,A}; // B is 9'b110100101 assign B = {1,A}; // B is 9'b110100101 assign B = {A,1'b1}; // B is 9'b101001011 assign B = {A,1}; // B is 9'b000000001 !!!!

**what's the difference between writing 1.0 and 1. or 2.0 and 2 ,** There is not difference in matlab. Sometimes, people like to write "1." instead of 1 to make it easier to port to/from other programming languages later, as it is a� The difference between 1, 01, 001 is 1 has no zeros, but 01 has one zero and 001 has two zeros. Login to reply the answers How do you think about the answers? You can sign in to vote the answer.

So, what's the difference between, say,

logic [7:0] count; ... count <= count + 1'b1;

and

logic [7:0] count; ... count <= count + 1;

Not a lot. In the first case your simulator/synthesiser will do this:

i) expand the `1'b1`

to `8'b1`

(because `count`

is 8 bits wide)
ii) do all the maths using 8 bits (because now everything is 8 bits wide).

In the second case your simulator/synthesiser will do this:

i) do all the maths using 32 bits (because `1`

is 32 bits wide)
ii) truncate the 32-bit result to 8 bits wide (because count is 8 bits wide)

The behaviour will be the same. However, that is not always the case. This:

count <= (count * 8'd255) >> 8;

and this:

count <= (count * 255) >> 8;

will behave differently. In the first case, 8 bits will be used for the multiplication (the width of the `8`

in the `>> 8`

is irrelevant) and so the multiplication will overflow; in the second case, 32 bits will be used for the multiplication and so everything will be fine.

**What number is in between -1 and 1?,** If there are an infinite amount of numbers between 1 and 2, how do we get from 1 to 2? What are two numbers whose sum is 99 and whose difference is 19? {1} is the set containing "1". {{1}} is the set containing the set which contains "1". {1, {1}} is a set with two members. One of them is "1". The other is the set containing "1". If you think of sets as being like empty boxes, clearly 1 is different to {1}, a box containing "1". {{1}} is a box containing a box which contains 1.

`1'b1`

is an binary, unsigned, 1-bit wide integral value. In the original verilog specification, `1`

had the same type as `integer`

. It was signed, but its width was unspecified. A tool could choose the width base on its host implementation of the `int`

type.

Since Verilog 2001 and SystemVerilog 2005, the width of `integer`

and `int`

was fixed at 32-bits. However, because of this original unspecified width, and the fact that so many people write `0`

or `1`

without realizing that it is now 32-bits wide, the standard does not allow you to use an unbased literal inside a concatenation. `{A,1}`

is illegal.

**The difference between +1 and -1,** This is because (-1) is interpreted as negative one, however (+1) is interpreted as the curried function (\x->1+x) . In haskell, (a **) is syntactic� I stand by my point: the only difference between i += 1 and ++i for integers (which is what is asked about) is a cosmetic one. – Alexandre C. Oct 20 '12 at 15:23. 2

**What's the difference between (1,) and (1) in python,** The comma makes it a tuple. (1) is just the same as 1 wrapped in delimiters. It can also be beneficial to know that there’s approximately a 1.5 size difference between men’s and women’s shoes, meaning a men’s 8 is roughly equal to a women’s 9.5. A size chart can help: Whenever you're shopping, try to find a size chart associated with the brand of shoes you’re interested in.

**Interpreting the Difference Between Two Numbers,** In real life, the difference between a and b is |a-b| (or |b-a|, which is the where we _would_ allow a negative difference; the one that comes to� If [code]i[/code] is a number then as far as I know they are all identical, except in the case of [code]i++[/code] the value of the entire expression is the value of [code]i[/code] before it is incremented, whereas with the other two (as well as [

**'The difference between' explained for primary-school parents ,** It is important that children learn that when we say: 'What is the difference between 1 and 6?' we mean: 'How many numbers do you count up from 1 to get to 6?' Hooks are classified by "sizes" -- for example, a size 1 hook is larger than a size 7, while a 1/0 is smaller than a 7/0 (pronounced 7-aught). The smallest standard sizes available are 32 and the largest 20/0. The slash symbol ( / ) defines a hook as grouped within the "aught" measurement system.