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CHARACTERISTIC & FUNCTIONS - Coggle Diagram
CHARACTERISTIC & FUNCTIONS
TYPES OF OPERANDS
Characters
A common form of data is text or character string. Most commonly used character code is the International Reference Alphabet (IRA). Another code use to encode characters is the
Extended Binary Coded Decimal Interchange Code (EBCIDIC)
Logical Data
An n-bit unit consisting of n 1-bit items of data, each item having the value of 0 or 1. The memory can be used most efficiently for storing an array of Boolean or Binary data items in which item can take on only the values 1 (true) and 0 (false)
Numbers
All machine languages include numeric data types. The numbers stored in a computer are limited. There are 3 types of numerical data that are common in the computer
(Binary Integer, Binary Floating Point and Decimal)
. Each decimal data represented by a 4-bit code with 2 digits stored per byte
(Packed Decimal)
MACHINE INSTRUCTION CHARACTERISTIC
Instruction Types
Arithmetic instruction provide computational capabilities for processing numeric data
(Data Processing).
Movement of data into or out of register and or memory locations
(Data Storage).
I/O Instructions are needed to transfer programs and data into memory and the result of computations back out to the user
(Data Movement).
Test instructions are used to test the value of the data word or the status of a computation
(Control).
Number of addresses
Instruction Representation
Within the computer each instruction is represented by a sequences of bits. Opcodes represented by abbreviation called mnemonics. E.g
ADD = addition
. Operands are also represented symbolically.
Instruction set design
Very complex because it affects so many aspects of the computer system. Defines many of the functions performed by the processor. Programmer's means of controlling the processor.
Elements of a machine instruction
Specifies the operation to be performed.
Operation code (opcode).
The operation may involve one or more source operands
(Source Operand References)
. The operation may produces a result
(Result Operand Reference).
This tell the processor where to fetch the next instruction after the execution of this instruction is complete
(Next Instruction Reference).
TYPES OF OPERATIONS
Conversion
Instruction that change the format or operate on the format of the data. An example is converting from decimal to binary. An example of a more complex editing instruction is the EAS/390 Translate (TR) instruction.
Input/Output
The approaches take are
isolated programmed I/O, Memory-mapped programmed I/O, DMA and use of I/O processor.
Many implementations provide only a few I/O instructions, with the specific actions specified by parameters, codes, or command words.
Logical
System Control
Instruction that can be executed only while the processor is in a certain privileged state or is executing a program in a special privileged area of memory.
Arithmetic
Most machine provide the basic arithmetic operations of add, subtraction, multiplication and divide. These are provided for signed integer (fixed point) numbers. Often, they are also provided for floating point and packed decimal numbers.
Transfer of Control
Reasons why transfer-of-control operations are required it is essential to be able to execute each instruction more than once. Most common transfer-of-control operations found in instruction sets
Branch, Skip, and Procedure call.
Data Transfer
Most fundamental type of machine instruction.