Why ISRO’s Vikram 3201 is a game-changer

WHAT makes Vikram 3201, India's first indigenously designed and built 32-bit processor, powerful and a game-changer?

While it may not power next-generation laptops, smartphones or high-performance gaming PCs, the Vikram 3201 chip, recently presented to Prime Minister Modi at Semicon India 2025, is slated to be a core component of the electronics for India's upcoming ambitious space missions, including the next journey to the Moon and the Gaganyaan human spaceflight mission to low-Earth orbit.

Designed by the Indian Space Research Organisation (ISRO) and manufactured by the Mohali-based Semi-Conductor Laboratory (SCL), the Vikram 3201 processor, named after India's space architect, Vikram Sarabhai, was successfully flight-tested aboard the PSLV-C60 mission launched on December 30, 2024, which undertook India's Space Docking Experiment (SpaDeX) technology. This advanced processor will replace Vikram 1601, a 16-bit processor used in its avionics since 2009, with this new-generation, indigenously made processor.

A surface-level comparison of the Vikram 3201 processor to those used in modern smartphones might prompt questions about the significance of this development. On a purely technical specification sheet, Vikram 3201's parameters do not match those of commercial electronics found in personal laptops and phones.

For instance, Vikram 3201 is a 32-bit processor, while most recent laptops are equipped with 64-bit processors. In simple terms, a 32-bit system is designed to access 2³² memory addresses, allowing it to work with up to 4 GB of RAM at a time. In contrast, a 64-bit processor can access a vastly larger number of addresses (264), enabling it to support over 8-GB or even 16-GB RAM. In a direct comparison for consumer tasks, a modern 64-bit processor would undoubtedly outperform a 32-bit one.

Furthermore, Vikram 3201 is fabricated on a 180-nm process, a technology that was prevalent from the late 1990s to the early 2000s. In contrast, even an inexpensive modern laptop, such as the one with an 11th-generation Intel Core i5 processor, is built on a significantly more advanced 10-nm process.

The term 'nm', or nanometre, refers to one billionth of a metre. In the context of chip manufacturing, it refers to the 'process node', which relates to the size and density of transistors on a silicon chip. A smaller 'nm' value allows for more transistors to be packed into the same physical area.

This increased density offers many advantages: electrons have shorter distances to travel, resulting in higher computational speeds and faster switching rates. Smaller transistors also require less power to function, leading to improved energy efficiency and longer battery life in portable devices.

Additionally, a smaller process node allows for a more compact chip design, aiding in the miniaturisation of devices like smartphones. The most cutting-edge technology available today has reached 3-nm and 2-nm processes, which are designed to deliver the highest performance per watt.

However, the requirements of space electronics differ fundamentally from those of smartphones. These systems must function reliably under the exceptionally harsh conditions of space, including extreme temperature variations, significant radiation and intense vibrations and acoustic shocks during launch.

Without the insulation of Earth's atmosphere, cosmic rays and solar wind, comprising high-energy charged particles, bombard electronics incessantly. In these devices, the zeros and ones of digital data are stored as charged and uncharged states within transistors. A charged particle from a cosmic ray can strike a transistor and flip this state, turning a 0 into a 1 or vice versa. This phenomenon is known as a Single-Event Upset (SEU), a tiny, random change that can alter the digital 'score' in a spacecraft's computer.

Critically, SEUs are more likely to occur in modern, smaller nanometre chips. As transistors shrink, each one holds less electrical charge, making it more vulnerable to having its state flipped by a single particle strike. This is precisely why the older 180-nm CMOS technology used in the Vikram processor was chosen for space applications.

These larger transistors offer inherent radiation tolerance, making them ideal for radiation-hardened designs without the need for extensive and costly protective shielding.

In addition to radiation tolerance, space electronics must endure extreme temperature variations. As a satellite orbits the Earth, it cycles between direct exposure to the sun and the darkness of the Earth's shadow. When facing the sun, its components can reach scorching temperatures of up to 125°C. When eclipsed, they can plunge to a frigid

-55°C within seconds. The electronics must reliably withstand these drastic and rapid fluctuations. Vikram 3201 is specifically designed for this, with an operating temperature range of -55°C to 125°C, making it perfectly suited for the space environment.

Plus, this technology supports higher operating voltages (eg 1.8V to 5V), ideal for solar-powered spacecraft.

For ISRO's critical needs, processing telemetry, navigation and control systems in rockets like the PSLV and in satellites, the paramount focus is on unwavering reliability, durability and extremely low failure rates. These requirements outweigh the need for the gigahertz speeds or high transistor density found in consumer electronics. Vikram 3201 is powerfully designed for this purpose, making it a true game-changer for India's quest for self-reliance in space tech.

Vikram 3201 represents a significant upgrade from its predecessor Vikram 1601, which was first deployed in the PSLV-C47 mission that placed the CARTOSAT-3 satellite in orbit in 2009. The new Vikram 3201 incorporates advanced features like floating-point support and compatibility with high-level languages, such as Ada, which streamlines software development for complex missions. Building on this success, it is reliably understood that ISRO is already exploring next-generation space-grade chip designs at the 70-nm node.

The applications of these processors extend far beyond space. Vikram 1601 demonstrated its versatility by being adopted for critical systems in control electronics for electric locomotives and sophisticated railway systems, such as Track Management Systems (TMS) and indigenous Automatic Train Supervision (i-ATS) for metro rail networks. Likewise, Vikram 3201 is expected to find valuable applications in other strategic and industrial sectors.

This move towards self-reliance was driven by necessity. Before Vikram 1601, ISRO heavily relied on imported processors, exposing India to supply chain risks, export restrictions and national security challenges. Sanctions imposed after the 1998 Pokhran tests sharply highlighted the importance of developing home-grown strategic technology.

Indian institutions then undertook the challenging task of developing indigenous tech. Though this meant lagging behind global commercial standards at times, the effort proved crucial. The presentation of the Vikram 3201 chip to PM Modi at Semicon India 2025 marks a crucial milestone in the decades of progress towards technological independence in the space sector.

TV Venkateswaran is Visiting Professor, IISER, Mohali.