types of instructions

DATA FORMATS
In selecting the number representation the following factors should be taken into account:
1. TYPES of NUMBERS to be represented e.g., integers, real numbers, complex numbers
2. The RANGE of VALUES to be encountered
3. The PRECISION of the NUMBER
4. THE COST of HARDWARE required to store and process the numbers

INSTRUCTION FORMATS
In selecting the instruction format(s) the following factors should be considered.
1. The number of instructions to be represented.
2. The addressability and addressing modes.
3. The ease of decoding.
4. Type of instruction field (fixed or variable)
5. The cost of hardware required to decode and execute instructions.
2.2 Instruction formats
Instruction code is a group of bits that instruct the computer to perform a specific operation. It is usually divided into parts, each having its own particular interpretation. The most basic part of an instruction code is its operation code operation part.
The format of an instruction is usually depicted in a rectangular box symbolizing the bits of the instruction as they appear in memory words or in a control register. The bits of the instruction are divided into groups called fields.
1. An operation code field that specifies the operation to be performed.
2. An address field that designates a memory address or a processor register.
2.3 Instructions Types
Computers may have instructions of several different lengths containing varying number of addresses. The number of address fields in the instruction format of a computer depends on the internal organization of its registers. Most computers fall into one of three types of CPU organizations: