What is overflow flag when overflow is set?

In computer processors, the overflow flag (sometimes called the V flag) is usually a single bit in a system status register used to indicate when an arithmetic overflow has occurred in an operation, indicating that the signed two’s-complement result would not fit in the number of bits used for the result.

How do you calculate overflow flag?

If the sum of two numbers with the sign bits off yields a result number with the sign bit on, the “overflow” flag is turned on. 2. If the sum of two numbers with the sign bits on yields a result number with the sign bit off, the “overflow” flag is turned on.

What is difference between overflow and flag?

Overflow and carry out are philosophically the same thing. Both indicate that the answer does not fit in the space available. The difference is that carry out applies when you have somewhere else to put it, while overflow is when you do not. As an example, imagine a four bit computer using unsigned binary for addition.

Which flag indicates the overflow from MSB?

Sign flag (SF) – the sign flag is set(1) when the result of an arithmetic operation has a 1 in the most significant bit (msb). Unsigned overflow means there has been a carry out of, or a borrow into, the most significant bit (msb) of the destination operand in an arithmetic operation using unsigned numbers.

How is the bit set on the 68000?

*The bit is set or cleared according to the outcome of the instruction. Unless an addressing mode is implicit (e.g., NOP, RESET, RTS, etc.), the legal source and destination addressing modes are specified by their assembly language syntax. The following notation is used to describe the 68000’s instruction set.

What kind of instruction set does the 68000 have?

(d,PC), (d,PC,Xi)Program counter relative addressing with a 16-bit offset, or with an 8-bit offset plus the contents of an index register. immAn immediate value (i.e., literal) which may be 16 or 32 bits, depending on the instruction. 1 The 68000’s Instruction Set

What is the current notation for the 68000 simulator?

The notation originally used to indicate address register indirect addressing has been superseded. However, the Teesside 68000 simulator supports only the older form. Old notation Current notation d(An), d(An,Xi) (d,An), (d,An,Xi) d(PC), d(PC,Xi) (d,PC), (d,PC,Xi) ABCD Add decimal with extend Operation:[destination] 10 ←[source] 10 + [destination]

What is the instruction set for the Teesside 68000?

2The 68000’s Instruction Set Two notations are employed for address register indirect addressing. The notation originally used to indicate address register indirect addressing has been superseded. However, the Teesside 68000 simulator supports only the older form. Old notation Current notation