Why DAA instruction is to be written just after add sub instructions?

Why DAA instruction is to be written just after add sub instructions?

The DAA (Decimal Adjust after Addition) instruction allows addition of numbers represented in 8-bit packed BCD code. It is used immediately after normal addition instruction operating on BCD codes. This instruction assumes the AL register as the source and the destination, and hence it requires no operand.

What does DAA instruction in 8085 MP do?

Let us consider we want to add two decimal numbers 38 and 45. They will be represented in BCD as 0011 1000 and 0100 0101. All that is required to be done is to add the BCD numbers and store the result in A, and then execute the DAA instruction. …

What is the significance of DAA instruction?

The DAA instruction is only useful when it follows an ADD instruction that adds (binary addition) two 2-digit, packed BCD values and stores a byte result in the AL register. The DAA instruction then adjusts the contents of the AL register to contain the correct 2-digit, packed BCD result.

What are the flags affected due to DAA instruction?

Flags Affected The CF and AF flags are set if the adjustment of the value results in a decimal carry in either digit of the result (see the “Operation” section above). The SF, ZF, and PF flags are set according to the result.

Which is direct addressing?

Direct addressing is a scheme in which the address specifies which memory word or register contains the operand.

What is Classful IP address?

Classful addressing is a concept that divides the available address space of IPv4 into five classes namely A, B, C, D & E. IP addresses, before 1993 use the classful addressing where classes have a fixed number of blocks and each block has a fixed number of hosts.

Who uses Class A IP addresses?

Class A IP addresses are used for huge networks, like those deployed by Internet Service Providers (ISPs). Class A IP addresses support up to 16 million hosts (hosts are devices that connect to a network (computers, servers, switches, routers, printers…etc.)

What is a Classful subnet?

Classful subnetting is a method of splitting a classful network number into two or more smaller subnets. The subnets will all be the same size, determined by the maximum number of hosts per subnet.