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What is Assembly Language?

Priya Pedamkar
Article byPriya Pedamkar

Updated August 18, 2023

Definition of Assembly Language

Assembly Language is a low-level programming language. It helps in understanding the programming language of machine code.

Machine code is a series of instructions that provide the necessary information to a user’s CPU (Central Processing Unit) to carry out a particular task (add, subtract, compare values, etc.). In computers, there is an assembler that helps in converting the assembly code into machine code executable. Symbolic machine code aims to understand the instruction and provide it to machine language for further processing. It mainly depends on the system architecture, whether it is an operating system or computer architecture.

 

 

Symbolic machine code mainly consists of mnemonic processor instructions or data and other statements or instructions. It establishes with the help of compiling high-level language source code like C and C++. It helps in fine-tuning the program.

Assembly language

Table of Contents

Key Highlights

  • It is a low-level, human-readable, programmable language in which each ASM instruction relates to a computer machine code instruction.
  • In comparison to other high-level languages, symbolic machine code refers to consistency. It only has a few operations, but it helps to know the algorithms and other control flows. It simplifies the code and makes it easier to debug.
  • By learning the assembler language, the programmer can write the code to access registers and retrieve the memory address of pointers and values.
  • If an individual wants to know how the system works and the processor as well, then symbolic machine code is the one that solves the purpose. It helps in all aspects, from understanding the program’s algorithm to the processor working and registering the computer’s register.

History of Assembly Language

It was featured in 1949, and its history interconnects with the stored-program computers. It became attention when they relieved programmers of tasks such as memorizing numeric codes. However, by the late 1950s, their use replaces by higher-level languages in the search for greater programming productivity. ASM is still used today for direct hardware manipulation, gaining access to specialized processor instructions, and dealing with critical performance issues. Typical applications of device drivers, low-level embedded systems, and real-time systems include their use in various contexts. Many commercial applications, such as large amounts of IBM mainframe software, were also written in assembly languages. Microcomputers relied heavily on hand-coded assembly languages in their early stages. It was due to a lack of high-level language compilers designed to operate on microcomputers. Another reason for the assembly language set at the time was that they had many advantages, such as small size, high speed, low overhead, and high reliability.

How Assembly Language Works?

Assembly language uses a series of mnemonic codes to represent machine language instructions. A programmer writes these codes in a text editor, and then an assembler program assembles them into machine language instructions that the computer can understand and execute.

The process of assembling the code involves converting the mnemonic codes into their binary equivalents, which the CPU can execute directly. The assembler program stores the resulting machine language instructions in an object or executable file that the CPU can load into memory and execute.

It provides programmers with direct hardware control, enabling them to access the low-level components of a computer system, such as the CPU, memory, and input/output devices. This makes it a valuable language for low-level programming tasks such as writing device drivers and real-time and embedded systems.

Additionally, assembler language is highly optimized for performance, allowing programmers to fine-tune the code to take full advantage of the underlying hardware. Assembly language programs can be minimal in size and require fewer resources than higher-level language programs, making them ideal for memory-constrained environments.

However, writing code in assembly language can be time-consuming and requires a deep understanding of hardware architecture. Therefore, Programmers often use assembly language only for specific tasks where its unique strengths are needed, while they use higher-level languages for other programming tasks.

Assemblers

It is translated into machine language by assemblers. An assembler allows software and application developers to access, operate, and manage a hardware architecture and components of a computer. It is also known as an assembly language compiler.

Types of Assemblers

There are two main types of assemblers used in computer programming:

Types of Assemblers

  1. Single-pass assembler: A single-pass assembler, also known as a one-pass translation, performs a complete scan of the source program input to the assembler or its equivalent representation and translates each statement based on the declaration. In other words, a single-pass assembler reads the entire source code and generates the corresponding machine code in one pass without requiring multiple iterations. It isolates the label, mnemonics, and operand field of the system. It validates the code instructions by looking them up in a mnemonic code table. It enters the symbol observed in the label field and addresses the available text’s machine word in the symbol table. This pass is fast and effective, and no need to construct the intermediate code.
  2. Multi-pass assembler: An assembler must go through assembly language several times to generate object code. This final pass is called a synthesis pass, and this assembler requires any form of an intermediate code to create each pass every time. It is comparatively slower than a single-pass assembler, but some actions can perform more than once means duplicated.

Components of Assembly Language

Understanding the Building Blocks of Low-Level Programming

Let’s examine a few assembly language components and how they convert to machine code.

  • Command: A command is an instruction in assembly code that tells the assembler what action to take. Assembly language commands frequently use abbreviations to keep the terminology short while also using self-descriptive abbreviations, such as “ADD” for addition and “MOV” for data transfer.
  • Label: A label is a word, number, or symbol that the assembly code uses to locate the date or instruction to use.
  • Operand: A variable or piece of data is an operand, which the assembler can manipulate. Users can tell the assembly language which data to apply whatever commands on that line by including operands in instructions.
  • Mnemonic: A mnemonic is a name given to a machine function or an abbreviation for an assembly language operation. In assembly, each mnemonic represents a machine instruction. An example of one of these machine instructions add. Mul, lea, and CMP are some other examples.
  • Registers: The processor can operate on numeric values (numbers) but must first save somewhere. The data is now kept in memory, inside the instruction opcode, or in special on-chip memory placed directly in the processor, known as registers. To work with a value, users don’t need to address it by address; instead, special mnemonic “names” such as ax on x86, A on Z80, or r0 on ARM are in use.
  • Macro: An assembly language macro is a template high-heel format that presents a series or pattern of statements. This set of assembly language statements is by several programs. A macro facility uses to interpret macro definitions, and a macro call inserts into the source code where “normal” assembly code would have gone instead of the macro set of statements.
  • Directive: A directive is a kind of instruction that informs the assembler how to change a setting or perform an action. An assembly language’s syntax frequently requires a specific character, such as a period, at the start of a directive. It instructs the assembler that the following text is a directive to follow.

Assembly Language vs High-Level Language

Assembly Language  High-Level language
Assembly language is machine-dependent. It is a low-level computer language that allows users to create a wide range of programs by representing a set of instructions with alphanumeric codes rather than numeric codes.

Example: ARM, MIPS, x86, Z80

 

 A high-level language is machine-independent. A high-level language is user-friendly, uses variables and functions, and is not dependent on the computer’s architecture.

 

Example: C, C++, Python, Javascript.

 

 
The assembly language requires an assembler to convert. A high-level language conversion requires the use of an interpreter or compiler.
It is closely related to hardware and is thus used to write hardware programs. It has no hardware interactions and is only used to write software application programs.
Faster program execution. Program execution is slow.

Debugging Assembly language Code

When debugging assembly language programs, effective debugging techniques include:

1. Debugger: A debugger is a part of the software that allows you to step through your assembly language program, examine the contents of registers and memory, and set breakpoints to stop the program at specific points for further examination.

2. Instruction set for assembly language: Understanding the assembly language instruction set, including the operation of each instruction, the registers it uses, and the flags it sets, will aid in understanding the program flow and the cause of the problem.

3. Print statements or data output to a file: It can be applied to inspect the values of variables and registers at specific points in the program to determine how the program behaves and where the problem is.

4. Examining memory: It is possible to determine whether the problem arises from incorrect memory access or incorrectly initialized data by inspecting the contents of the memory.

5. Using a simulator: The assembly code operates in a simulated environment without the requirement for the target hardware using a simulator.

6. Profiling Tools: Profiling tools can detect performance bottlenecks, memory leaks, and hotspots in assembly code.

Application

Real-world applications are one of the most valuable applications of Assembler language programming.

  • LED (LIGHT EMITTING DIODE): Light Emitting Diodes (LED) are the most common components, typically used to display the digital states of pins. Typical uses of LEDs include alarm devices, timers, and confirmation of user input, such as a mouse click or keystroke.
  • 8051 Trainer Kit: The PS-TRAINER-8051 trainer kit recommends for learning and developing MCU designs from Intel and NXP. It can connect to a PC’s 101/104 keyboard to enter user programs written in Assembly languages.
  • Interfacing LED with 8051: The LED in the 8051 Trainer Board works by turning on an LED, then off, and then looping back to START. However, because the microcontroller’s operating speed is very high, the flashing frequency will be sufficiently fast to be detected by the human eye.

Assembly Program to ON and OFF LED using 8051

MEMORY ADDRESS OPCODE MNEMONICS
9100 74 55 L1:MOV A,#FF
9102 7C MOV B0,A
9104 12 91 0F LCALL DELAY
9107 74 00 MOV A,#00
9109 7C MOV B0,A
910b 12 91 0F LCALL DELAY
910D 80 F9 SJMP L1
910F 7D 05 DELAY: MOV R5,#05
9111 7C FF H3 MOV R4,#FF
9113 7B FF H2 MOV R3,#FF
9115 DB FE H1: DJNZ R3,H1
9117 DC FA DJNZ R4,H2
9119 DD F6 DJNZ R5,H3
911B 22 RET

Future of Assembly language

  1. Specialized applications: It will continue to be important in technical applications such as embedded systems, real-time systems, and device drivers that require low-level hardware control and high performance.
  2. Limited use: Assembly language is likely to become more specialized and limited to specific areas where its unique strengths are required.
  3. Higher-level languages: As higher-level languages evolve and become more efficient, the need for assembler language programming in many applications will likely reduce.
  4. Compiler optimization: Advances in compilers and optimization techniques have made it possible to write high-performance code in higher-level languages, reducing the need for assembler language programming.
  5. Interpreted languages: The increasing popularity of interpreted and just-in-time compiled languages, such as Python and JavaScript, has further reduced the need for low-level programming.
  6. Computer science education: Assembler language will remain essential to computer science and engineering education, providing a deeper understanding of computer architecture and low-level programming.

While the use of symbolic machine code may decline in some areas, it will continue to play a critical role in specialized applications where its strengths in performance and hardware control are required.

Why is Assembly Language Useful?

It helps programmers in coding human-readable code that is relatively identical to machine language. Machine language is difficult to understand and read as it is just a series of numbers. Assembler language gives complete control over what tasks a computer performs.

ASM language is an official language that connects hardware and software. The following are the main characteristics of ASM languages that make users suitable for modern programming:

  1. Direct hardware control: Assembler language allows programmers to have direct control over the hardware of a computer system, such as the CPU, memory, and input/output devices. This makes it a valuable language for low-level programming tasks, such as writing device drivers.
  2. High performance: Programs written in ASM language can be highly optimized for performance, making them ideal for applications that require fast execution times, such as real-time systems and scientific simulations.
  3. Small code size: Assembly language programs tend to be smaller than programs written in higher-level languages, which can be advantageous in memory-constrained environments, such as embedded systems.
  4. Portability: Programmers can write Assembler language code to be portable across different computer architectures, enabling them to adapt programs to run on other hardware platforms efficiently.
  5. Education: Symbolic machine code is often used in computer science and engineering courses to teach students about computer architecture and system-level programming.
  6. Human readable: Assembler languages use words, numbers, and other textual components to create instructions to understand, remember, and recreate. As a result, symbolic machine code is relatively simple to use and learn while still forming an executable command for the machine.
  7. Assist debugging: The language is useful for error handling because programmers can read every line to understand how the code fails. It is more potent than the debugger in typical debugging because assembler language can be used to find issues with pointer arithmetic and memory corruption.

Example:

Find the below steps to print “Hello, World” on Windows

  1. Open the notepad.
  2. Write below code

global _main

extern _printf

section .text

_main:

push     message

call      _printf

add      esp, 4

ret

message:

db ‘Hello, World!’, 10, 0

  1. Save the file with any name, for example, XYZ.asm, with the extension.’ asm.’
  2. The above file must compile using the NASM assembler (Netwide Assembler).
  3. Run the command nasm –f win32 XYZ.asm.
  4. Nasm then generates one object file, XYZ.obj, which contains machine code but not executable code.
  5. Minimal GNU, which includes the GCC compiler, is used to create the executable file for Windows.
  6. Run the command gcc –o XYZ.exe XYZ.obj
  7. Execute the executable file now, ‘XYZ.’
  8. It will print “Hello, World!” as the output.

Why should you learn Assembly Language?

The learning of ASM is still helpful for programmers. It helps in taking complete control over the system and its resources.

  • By learning ASM language, the programmer can write the code to access registers and retrieve the memory address of pointers and values. It mainly helps in speed optimization, which increases efficiency and performance.
  • ASM language learning helps in understanding the processor and memory functions. If a programmer is writing a program that requires a compiler, the programmer requires a complete understanding of the processor.
  • ASM language helps in understanding the work of processors and memory. It is a cryptic and symbolic language.
  • ASM Language helps in contacting the hardware directly. This language forms mainly on computer architecture, and it recognizes a specific type of processor and is different for different CPUs.
  • ASM language refers to transparency compared to other high-level languages. It has a small number of operations, but it helps understand the algorithms and other control flows. It makes the code less complex and easy to debug as well.

Features of Assembly Language

The following are the features of the ASM:

  1. It can use mnemonic than numeric operation code, and it further reports any error in the code.
  2. This language helps specify the symbolic operand, which means it does not need to specify the machine address of that operand. It represents in the form of a symbol.
  3. The data declare by using decimal notation.
  4. Errors and bugs are easily identified and resolved.
  5. ASM language is simple to understand and execute.

Tips and Tricks

It could be supplementary reading for assembler language Programming.

  1. Using instructions with very few bytes.
  2. Using memory variables to implement.
  3. According to a basic rule in ASM language programming. The register operation is much faster than the memory operation.
  4. An x86 processor uses little-endian order to store and retrieve data from memory (low to high). The least significant byte saves at the data’s first memory address. The Remaining bytes are in the memory positions that follow.
  5. Use a macro to generate memory blocks during assembly rather than at runtime.
  6. All loop logic encapsulates within the loop body.
  7. Regarding the procedure, develop a simple calling interface.
  8. Don’t use the OFFSET operator to get the address of an indirect operand pointing to an object because OFFSET can only take the address of a variable defined in the data segment.
  9. In ASM language programming, an integer variable can be either signed (SBYTE, SWORD, and SDWORD) or unsigned (BYTE, WORD, and DWORD).
  10. Ignore using multiple RET to build procedures because ASMlanguage programming directly defines memory addresses and any labels. Hence, a direct jump without using CALL or INVOKE would be ideal.

Advantages and Disadvantages

Mentioned are some advantages and disadvantages:

Advantages Disadvantages
It allows complex jobs to execute in a standard way. Require a lot of time and endeavor

to write the code for the same.
It is memory efficient, as it requires less memory It needs more size or memory of the computer to run more programs written in ASM Language
It is faster, as its execution time is less. The syntax is difficult to remember.
It is mainly hardware-oriented. It has a lack of portability of programs between different computer architectures.
It requires less instruction to get the result. It is very complex and tough to understand.
It utilizes for critical jobs. It is not suitable for a few industries
It is not necessary to keep track of memory locations.

 

 It is a challenging task to identify and rectify the errors in the code.
 It is a low-level embedded system. It is not portable.

Final Thoughts

Assembly language is essential for understanding computer architecture and programs for programmers. The programmers mainly used many other programming languages for application development and software, but ASM language is also significant. It helps programmers to achieve a lot if they implement the ASM language. Assemblies contain a lot of metadata, that as version numbers, localization details, and other product details. It is an important part and displays to the user after being digitally signed.

If an individual wants to know how the system works and the processor as well, then ASM language is the one that solves the purpose. It helps in all aspects, from understanding the program’s algorithm to the processor working and registering the computer’s register. It depends on individual choice with which language to continue.

Frequently Asked Questions (FAQs)

Q1. Why is it called ASM Code?

Answer: “Assembly language” means a kind of low-level programming language that directly controls a computer’s hardware. The term “ASM language” refers to the process of translating mnemonics (abbreviations or acronyms) into machine code instructions (also known as “assembler”). In comparison, higher-level languages like C and Python translate into machine code by a compiler or interpreter.

Q2. What is the basic syntax of ASM Code?

Answer: Any ASM language program consists of three sections

Data section: The data section utilizes to declare initialized data or constants. This information does not change during execution. In this section, you can confirm various constant values, file names, buffer sizes, etc.

The syntax for initiating the data section

section.data

BSS section: The bss section is where variables are declared.

The syntax for the BSS section

section.bss

Text Section: The text section is where the source code is secured. ASM language instructions and assembler directives may include in the text section.

The syntax for initiating the Text section

section.text

global _start

_start:

The global_start declaration shows the kernel where program execution begins.

Syntax of Assembly Language Statements

[label] mnemonic [operands] [comment]

ASM language statements enter one per line. A basic instruction consists of two parts: the name of the commands (or mnemonic) to execute and the operands or command parameters.

Q3. What is the difference between ASM language and C language?

Answer:

C language  Assembly language
 The C programming language is portable and does not require a specific platform. The code written in C can easily reuse on another platform. Assembly does not provide portability or processor-specific source code because assembly instructions depend on the processor architecture.
C is convenient to use for making more complex programs. ASM language is much more flexible, allowing you to work with memory, interrupts, micro-registers, etc.

Q4. What is another name for an ASM language?

Answer: ASM language ( assembler or symbolic machine code), commonly abbreviated as ASM or asm, is any low-level programming language with a solid correspondence between the instructions in the language and the architecture’s machine code instructions.

Q5. What are the registers in the ASM language?

Answer: The processor includes a few internal memory storage locations known as registers to speed up processor operations. It stores data elements for processing without requiring memory access. The number on the processor chip is limited.

Processor Registers: A processor register (CPU register) is one of a small group of data storage locations built into a computer processor.

The registers classify into three types.

General registers: General Registers, also known as General Purpose Registers, that store data and addresses.

The general registers are categorized as follows:

DX (Data register): The AX register in the 8086 microprocessor is a 16-bit data register split into two 8-bit registers, AH and AL. It is commonly used in 8-bit instructions, can be utilized as a port number in I/O operations, and is employed for multiplication and division with specific instructions for each operation.

Pointer and Index register: These registers store data and instruction offsets. The offset is the distance between a variable, label, or instruction and its base segment.

Control Registers: Intel-architecture processors have a collection of control registers used to configure the processor at run time (such as switching between execution modes).

Segment Registers: Segments are programmatically defined areas that contain data, code, and stack.

Q6. What are the resources for Learning ASM code?

Answer: ARM, MIPS, and X86 are widely used assembler language programs.

Courses:

1. Learn ASM Language by Making Games for the Atari 2600

This ASM language course online will teach you the fundamentals of programming games using 6502 ASM language.

2. ASM Programming

This course teaches you how to create applications using ASM language programming and learn the fundamentals of project creation, the structure of assembly code, and advanced topics such as function recursion and system calls.

Tools

  1. Assembler: The Assembler program helps to generate ASMlanguage mnemonics for instructions into binary codes.
  2. Linker: A linker is a program that joins multiple object files into a single large object file.
  3. Locator: A locator is a program used for a particular address that determines the sections of object code to load into memory.

Q7. How is For Loop implemented in assembly language to calculate the sum?

Answer: The “LOOP target” statement performs two functions:

  • decrement ECX
  • if ECX != 0, jump to a target

To evaluate sum of n+(n-1)+…+2+1

mov ecx, n

xor eax, eax

L1:

add eax, ecx

loop L1

mov sum, eax

Q8. What is the primary function of an assembler?

Answer: Assembler is a program that converts ASM language to machine language. An assembler’s primary function is to assign addresses to labels. It converts the basic commands and operations from assembly code into binary code that can recognize by a specific type of processor. Assemblers, like compilers, create executable code.

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