Embedded vs. General-Purpose Software

What is Embedded Software?

Embedded software is software that is built into a specific device or apparatus to control and operate that device. It is a core component of what is known as an "embedded system."
A key characteristic of embedded software is that it is specially designed for a specific purpose. For example, the embedded software in an air conditioner is specialized for functions such as temperature control and switching between operating modes, and cannot be used for any other purpose.

Embedded software is used to operate familiar products such as those listed below.

• Home appliances: Washing machines, microwave ovens, refrigerators, air conditioners
• Automobiles: Engine control, braking systems (ABS), car navigation systems
• Communication equipment: Routers, smartphone base stations
• Industrial equipment: Control devices for factory production lines, sensors
• Medical equipment: Electrocardiographs, MRI machines, ventilators
• Others: Digital cameras, printers, ATMs, elevators

In fact, the number of microcontrollers (MCUs) running embedded software in modern society far exceeds the number of PCs and smartphones. According to recent surveys, more than 30 billion microcontrollers are shipped worldwide annually, the vast majority of which are used in embedded systems.

What is General-Purpose Software?

On the other hand, “general-purpose software” refers to software that runs on general-purpose computers such as PCs and smartphones, and can be used by users for various purposes.
Specific examples of general-purpose software include the following:

• Operating systems: Windows, macOS, Linux
• Office software: Microsoft Office, Google Workspace
• Web browsers: Chrome, Firefox, Safari
• Image editing software: Photoshop, Illustrator
• Development tools: Visual Studio, Eclipse

General-purpose software allows users to perform various operations and produce different types of outputs according to their purposes, and can be installed or removed relatively freely.

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Main Differences Between Embedded Software and General-Purpose Software

1. Differences in Purpose and Application

“Embedded software” is specifically designed to achieve a particular function. For example, embedded software in a digital camera is specialized for functions such as capturing, processing, and saving images. In contrast, “general-purpose software” can be used for multiple purposes, allowing users to utilize it for various tasks. Web browsers support a wide range of uses, such as reading news, watching videos, and shopping online.

2. Differences in Relationship with Hardware

“Embedded software” is closely tied to hardware and directly controls sensors and actuators (such as motors). It is optimized for the hardware specifications and, in many cases, only runs on specific hardware. For example, the control software for a refrigerator from a certain home appliance manufacturer is developed solely for that refrigerator, and in many cases, it will not operate properly on different product series.

In contrast, “general-purpose software” accesses hardware through an operating system such as Windows, so it is relatively less dependent on specific hardware. Therefore, the same software can be run on computers from different manufacturers.

3. Differences in Resource Constraints

“Embedded software” must operate with limited hardware resources (memory, CPU performance) due to constraints such as equipment manufacturing costs, power consumption, and size. For example, microcontrollers installed in home appliances typically operate in environments with memory ranging from a few kilobytes to a few megabytes and clock frequencies of several tens of MHz. Therefore, there are strict constraints on program size and execution speed.
In comparison, modern computers on which “general-purpose software” runs are equipped with several gigabytes of memory and high-speed CPUs, so resource constraints are not as strict as in embedded systems. In recent years, technological advances have made it possible to use higher-capacity memory and faster CPUs in embedded systems than before. However, compared to computers, there are still resource constraints, and designs must take these into consideration.

4. Differences in Real-Time Performance

Many types of “embedded software” require “real-time performance” to complete processing within a specified time. This is strictly required, especially for products related to human safety. For example, an automotive brake control system must respond within a few milliseconds after the driver presses the brake. Strict time constraints also exist in control systems for medical devices and aircraft.
In contrast, typically “general-purpose software” other than games and similar applications, real-time performance is not as highly emphasized. This is because even if some delay occurs, it often does not significantly affect the user experience.
Embedded software requires a specialized design capable of ensuring that processing is always completed within a specified time while handling numerous inputs and outputs, which is a major difference between embedded software and general-purpose software.

5. Differences in Reliability and Safety

Embedded software is required to operate stably over a long period of time. Especially in industrial equipment, extremely high reliability is required because software defects can affect human lives or have a major impact on corporate production costs. Therefore, strict testing and certification processes are implemented for many devices, and the devices are required to operate without error 24 hours a day, 365 days a year. In addition, once embedded in a product, many devices are not connected to an external network, making them difficult to update easily. Therefore, it is necessary to develop high-quality software from the initial stage.

Reliability is also important for “general-purpose software,” but even if bugs are found, they can often be fixed with updates, so there is a tendency not to require the same level of strictness as embedded software.

6. Differences in Development Languages and Tools

For the development of “embedded software,” C and C++ languages, which can directly control hardware, are mainly used. Assembly language may also be used. The development environment is specialized, requiring dedicated tools such as cross-compilers (compilers that generate programs that run on a target CPU different from the CPU of the development computer), debuggers, and ICEs (In-Circuit Emulators).
For the development of “general-purpose software,” various high-level languages such as C#, Java, Python, and JavaScript are used. The development environment is also well-equipped, with a wealth of integrated development environments (IDEs) and debugging tools available.

7. Differences in User Interfaces

“Embedded software” often has a minimal user interface, consisting of LED indicators, simple LCD screens, button operations, and so on. It is not uncommon for it to lack an advanced graphical user interface (GUI).
“General-purpose software” is operated using a rich GUI on a monitor or smartphone screen, and can be used intuitively using a mouse or touch screen.

The Appeal of Embedded Software Development

We have looked at the differences between embedded software and general-purpose software above, but how does embedded software development differ in appeal from general-purpose software development?
One key attraction is the opportunity to be involved in both hardware and software development. The process of reading sensor values, controlling motors, and enabling the physical operation of equipment is highly rewarding for engineers who want to “make things and make them work.”

In addition, “having the software you developed take shape as an actual product” is also a major appeal. Seeing a product you were involved in developing being sold at a home appliance store, or having your code embedded in a car running on the road, will bring a great sense of accomplishment.

Furthermore, embedded software plays an “important role in supporting social infrastructure.” The opportunity to work in fields directly linked to people’s lives and safety, such as medical devices, transportation systems, and industrial equipment, has great social significance.

The world of embedded software is constantly changing with the evolution of technology. With the spread of IoT (Internet of Things) and AI (artificial intelligence), embedded systems are becoming increasingly sophisticated and important. A career in this field offers great potential for the future.

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