What does status register contain?

What does status register contain?

The status register is a hardware register that contains information about the state of the processor. The status register lets an instruction take action contingent on the outcome of a previous instruction. Typically, flags in the status register are modified as effects of arithmetic and bit manipulation operations.

What are the components of flag register?

All FLAGS registers contain the condition codes, flag bits that let the results of one machine-language instruction affect another instruction. Arithmetic and logical instructions set some or all of the flags, and conditional jump instructions take variable action based on the value of certain flags.

What are the contents of status register Sreg after ADD and ADC instruction?

The representation of the 8 bits in the status register are:

1. Bit 0: Carry Flag.
2. Bit 1: Zero Flag.
3. Bit 2: Negative Flag.
4. Bit 3: Two’s Complement Overflow Flag.
5. Bit 4: Sign Bit.
6. Bit 5: Half Carry Flag.
7. Bit 6: Bit Copy Storage.
8. Bit 7: Global Interrupt Enable.

What is the status of carry flag?

In computer processors the carry flag (usually indicated as the C flag) is a single bit in a system status register/flag register used to indicate when an arithmetic carry or borrow has been generated out of the most significant arithmetic logic unit (ALU) bit position.

What are the 4 bit used in status register?

The most significant four bits of the xPSR are the condition code bits, Negative, Zero, Carry, and oVerflow. These will be set and cleared depending on the results of a data processing instruction. The result of Thumb-2 data processing instructions can set or clear these flags.

What is Flag Register and its types?

The Flag register is a Special Purpose Register. There are total 9 flags in 8086 and the flag register is divided into two types: (a) Status Flags – There are 6 flag registers in 8086 microprocessor which become set(1) or reset(0) depending upon condition after either 8-bit or 16-bit operation.

What is the role of flag register?

The Flag register is a Special Purpose Register. Depending upon the value of result after any arithmetic and logical operation the flag bits become set (1) or reset (0). If the MSB is 0, it indicates the number is positive and the sign flag becomes reset i.e. 0. …

Which flag bit of status register is affected by BST instruction?

A bit from a register in the register file can be copied into T by the BST instruction, and a bit in T can be copied into a bit in a register in the register file by the BLD instruction. The half carry flag H indicates a half carry in some arithmetic operations.

What is Flag register and its types?

What is the difference between carry flag and auxiliary carry flag?

From what I seem to know by now is that the Carry Flag is used when you try, let’s say, 255+9 when you only have 8 bits for data, The Auxiliary Flag is the same, but only for the 4 last bits?? And The Overflow is used when you have 7 bits for the binary number and the 8(left-most ) is used for the sign???

What is general purpose register?

General purpose registers are used to store temporary data within the microprocessor. It is of 16 bits and is divided into two 8-bit registers BH and BL to also perform 8-bit instructions. It is used to store the value of the offset. Example: MOV BL, [500] (BL = 500H) CX – This is the counter register.

What is the format of the flag register in 8086?

The format of flag register is like below. We can divide the flag bits into two sections. The Status Flags, and the Control Flags. In 8086 there are 6 different flags which are set or reset after 8-bit or 16-bit operations. These flags and their functions are listed below.

Is the flag register a special purpose register?

The Flag register is a Special Purpose Register. Depending upon the value of result after any arithmetic and logical operation the flag bits become set (1) or reset (0). (a) Status Flags – There are 6 flag registers in 8086 microprocessor which become set (1) or reset (0) depending upon condition after either 8-bit or 16-bit operation.

How many flags are there in the 8085 microprocessor?

In 8085 microprocessor, flag register consists of 8 bits and only 5 of them are useful. The 5 flags are: Sign Flag (S) – After any operation if the MSB (B (7)) of the result is 1, it indicates the number is negative and the sign flag becomes set, i.e. 1. If the MSB is 0, it indicates the number is positive and the sign flag becomes reset i.e. 0.

How many bits are in the flag register?

The Flag register is a Special Purpose Register. Depending upon the value of result after any arithmetic and logical operation the flag bits become set (1) or reset (0). In 8085 microprocessor, flag register consists of 8 bits and only 5 of them are useful.