What is meant by instructions and operation?

Nowadays, electrical engineers are required to evolve their practices by incorporating embedded processes, microcontrollers, digital signal processors, and so on. These processors are beneficial in many ways and have changed the perspective of electronic design.

Instructions are commands given to the microprocessor to perform a specified operation (arithmetic or logical) for the given data. The operations and equivalent instructions of the machine learning process are a crucial part in guiding the appropriate procedure to use the devices containing the latest and advanced technology.

Terms and devices in general use

CPU

The central processing unit (CPU) comprises a data path where the binary information is handled by certain arithmetic operations, bitwise-shifting, and so on, along with a control unit that is useful for managing the data flow and producing control signals. They are also responsible for the data path to operate or perform the operations as per the instruction.

Processor

It contains CPU and extra elements that assist the CPU to perform more effectively although there isn’t much requirement of transforming the CPU into a processor the memory will not be of any use unless an input/output system permits to write data inside the memory or read data outside the memory. Multiple processors together form a microprocessor which has an integrated circuit.

Microcontroller

It is an integrated device with an amalgamation of a microprocessor with hardware-based minor like timers, serial communicators, and so on.

Operand

It is the mathematical operation to be operated on. It is the input quantity in a specific equation. For instance, 6 + 3 = 9, here ‘6’ and ‘3’ are the two input operands whereas ‘+’ is the operator and ‘9’ is the output. An operand is a part of the computer instruction to select what data requires to be operated and in context with the assembly language, an operand is a quantity on which the instruction (mnemonic) operates. The operand may be a register, a memory, or a label. For example, x86 architecture.

Machine language

Processors use machine language or machine code, unlike any assembly language where the binary instructions are captured inside the program memory performed by the control unit. The machine-language instruction includes an important branch known as an opcode (operation code) that conveys to the processor any specific action to be performed and memory position for data storage, numerical values as well as program memory. The assembly language is the human version of machine language that contributes to a combination of letters (ADD, JMP, MOV, etc.) instead of binary operation codes.

Instruction Set Architecture (ISA)

It is a Computer Architecture type including a cluster of machine-language instructions into a consistent processing operation architecture. ISA needs to be researched for the study of the processor’s performance and characteristics. The instructions are defined features that make the processor perform.

RISC (Reduced Instruction Set Computer)

RISC highlights generic instructions that correlate to the standard computational operations which are uniform in time of execution and length. Imposing these instructions is greatly optimized and pipelining is needed to maximize the execution speed. The more the registers, the less is the memory used and instructions that get memory access tend to be slow. E.g., RISC-V. The creators of the RISC-V architecture decided not to set up a trap for divide-by-zero events, that is, in certain situations, the code should contain an extra branch instruction and operation for error handling.

CISC (Complex Instruction Set Computer)

CISC imposes specific instructions that can be more directly execute the complicated operations required in software. This makes it simpler to translate languages to assembly. Complex instructions need minimum memory. For instance, RISC requires three instructions to operate or carry out the operations and a CISC needs only a single instruction to operate or perform any operations.

Any physical processor needs a semiconductor fabrication plant for operations to take place and the chips that come out of the assembly line bear a certain cost.

Integrated Circuit (IC)

Integrated circuit (IC) processors are generated in huge quantities by a highly-automated metal-oxide-semiconductor (MOS) fabrication procedure that results in a low unit price. A minimal hypothetical microprocessor may contain an arithmetic logic unit (ALU) as well as a control logic section. ALU is responsible for various arithmetic instructions like addition, subtraction, AND or OR operators. Every ALU operation sets one or more flags that indicate the results of the last operand used. One operation code may affect several data paths, registers, and other components of the device.

The volume of data objects becomes larger; giving access to more transistors on a chip and permitting the word sizes to increase from 4 and 8-bit words and ultimately to 64-bit words. The floating-point unit integration, firstly as a different IC and then as a microprocessor chip section increased the speed of the floating-point calculations. Rather than processing the long word on one IC, multiple circuits connected in parallel processed subsets of every word, and the result was a system that could sustain 32-bit words using IC with space for only four bits each. The 16-bit Intel x86 processors (80386) do not contain floating-point units (FPUs). Non-programmable controls need the bulky, or costly implementation to obtain the results feasible with a microprocessor. Bitwise is the level of operands that defines working with individual bits (smallest data units) in a computer.

Arithmetic operations used in microprocessor

Some of the arithmetic instructions used in microprocessor are:

ADD

In the ADD operation summation of data in two different registers is done. Memory to memory operations is not feasible. The source and the destination operand cannot be a memory location and the content of the segment register cannot be summed up.

ADC (Add with carry)

Similar to the ADD instruction, but it adds the carry flag bit.

SUB

It substracts the source operand from the destination and final data is stored in the destination. Both operands may not be a memory operand and destination operand should not be immediate data.

SBB (Subtract with borrow)

Similar to the SUB instruction but Borrow flag (BF) or Carry flag (CF) is also subtracted.

CMP (Compare)

For comparison, it subtracts the source operand from the destination, but the result is not stored anywhere. It is used to compare inputs specified by the user.

INC (Increment)

This instruction increases the byte or word by 1 and immediate data cannot be an operand. The INC instruction adds 1 to any register or memory location. It affects AF (Adjust Flag), OF (Overflow Flag), PF (Parity Flag), SF (Sign Flag), and ZF (Zero Flag) but CF (Carry Flag) is not affected.

DEC (Decrement)

This instruction decreases the memory data by 1 and immediate data cannot be an operand.

There are any other arithmetic operations include DAA (Decimal adjust accumulator), DAS (Decimal address after subtraction), etc. that are used for arithetic operations in microprocessors.

Logical Operations used in microprocessor

Some of the logical instructions used in microprocessor are AND, OR, NOT, XOR (logical Exclusive OR), SHL (Shift left logical), SHR (Shift right logical), SAR (Shift Arithmetic Right), ROR (Rotate Right without carry), ROL (Rotate left without carry), RCR (Rotate right through carry), and RCL (Rotate left through carry).

Context and Applications

• Bachelors in Technology (Electrical Engineering)
• Masters in Science (Micro Processing Units)
• Masters in Science (Electronics and Telecommunications)
• Masters in Science (Robotics and Machine Learning)

Practice Problems

Q1. What is the full form of ISA?

1. Instruction Set Architecture
2. Instruction Structure Architecture
3. Instruction Set Asset
4. Internal Set Architecture

Correct option- a

Explanation: The full form of ISA is Instruction Set Architecture.

Q2. What is known as a level of operands that defines working with individual bits in a computer?

1. Operand
2. Bitwise
3. Compiler
4. Byte

Correct option- b

Explanation: Bitwise is known as a level of operands that defines working with individual bits in a computer.

Q3. What is not included in the 16-bit Intel x86 processors (80386)?

1. Memory location
2. Encode
3. Floating-point Units (FPUs)
4. Arithmetic instructions

Correct option- c

Explanation: Floating-point units (FPUs) are not included in the 16-bit Intel x86 processors (80386).

Q4. What is the full form of RISC?

1. Reduced Implementation Set Code
2. Reactive Instruction Set Code
3. Ranked Instruction Static Computer
4. Reduced Instruction Set Computer

Correct option- d

Explanation: The full form of RISC is a reduced instruction set computer.

Q5. Which one of the following is a human version of machine language that contributes to a combination of letters rather than binary operation codes?

1. Assembly language
2. Machine language
3. Coding language
4. Python language

Correct option- a

Explanation: The assembly language is a human version of machine language that contributes to a combination of letters rather than binary operation codes.

Related Concepts

• UNIX System V operating system
• Micro-operation in ASCII