# What does the zero flag do?

## What does the zero flag do?

Along with a carry flag, a sign flag and an overflow flag, the zero flag is used to check the result of an arithmetic operation, including bitwise logical instructions. It is set to 1, or true, if an arithmetic result is zero, and reset otherwise.

## How do you implement a zero flag?

Implementing a zero flag for a register should be straight forward, it would be a logical NOR of all the bits on the register. Something like that would work for a small number of inputs. As for a 64-bit processor you cannot make one gigantic NOR gate with 64 inputs. The fan-in would be too high.

Which flag is set when the result is zero?

These set of instructions will reset the sign flag to 0 as 40 – 30 is a positive number. Zero Flag (Z) – After any arithmetical or logical operation if the result is 0 (00)H, the zero flag becomes set i.e. 1, otherwise it becomes reset i.e. 0.

### What do you mean by status flag?

A status register, flag register, or condition code register (CCR) is a collection of status flag bits for a processor. For example, a Z bit may be set if the result of the operation is zero and cleared if it is nonzero. Other classes of instructions may also modify the flags to indicate status.

### When to use the zero flag in arithmetic?

Along with a carry flag, a sign flag and an overflow flag, the zero flag is used to check the result of an arithmetic operation, including bitwise logical instructions. It is set to 1, or true, if an arithmetic result is zero, and reset otherwise.

When to use carry flag or zero flag?

the zero flag is quite simple if the result of the operation is a zero the zero flag will be set otherwise it will be clear. The carry flag is used a number of ways but in this case with an add operation, it is the carry out bit, an unsigned overflow.

#### When do you use the zero flag in a processor?

It is also common that processors have a bitwise AND-instruction that does not store the result. In most processors, the zero flag is mainly used in conditional branch instructions, which alter control flow on previous instruction results, but there are often other uses as well.

#### What is the difference between flag = 0 and Flag = 1?

The feedback you provide will help us show you more relevant content in the future. Answer Wiki. If flag is 0, this means that it has not been set, if it is 1 – it is set. For example, if you do arithmetic calculations and the result is 0, your Zero flag would be 1, since the result = 0.