What is VME
Overview of VME
VME (VERSAmodule Eurocard) is a long-standing parallel bus standard for use in embedded applications, with development having started in the early 1980s and standardisation occurring in 1987. It provides a common backplane that allows multiple boards, such as processors, I/O cards, and storage modules, to communicate with one another efficiently.
VME’s key strengths lie in its reliability, rugged Eurocard design and strong focus on backward compatibility. This means new processing boards can often be added to existing systems without needing to replace the entire enclosure or backplane, making VME highly cost-effective for long-lifecycle applications.
For several decades it has been widely deployed in a range of industrial, research, semiconductor process control, transport and medical applications.
A market where VME has proven to be an enduring technology is defence. From its inception in the 1980s, VME architecture has been leveraged for many defence applications and platforms, including air defence systems, main battle tanks, and even nuclear submarines.
Many of these applications have now migrated to more modern and higher bandwidth architectures, such as VPX, however the VME bus architecture continues to be widely used.
This is especially the case in defence where platforms remain in service for many years and undergo several upgrades over their life. VME’s robust design, reliability and backwards compatibility are key advantages in this context.
What does VME stand for?
VME stands for VERSAmodule Eurocard.
VERSA – from Motorola’s earlier VERSAbus architecture
module – referring to plug-in modular circuit boards
Eurocard – the physical board format the system is based on
Timeline of VME
1979–1980 – Motorola develops VERSAbus for its 68000 processor systems.
This becomes the conceptual foundation for what evolves into VME.
1981 – Motorola, Mostek, and Philips collaboratively design a new bus specification based on VERSAbus and the Eurocard mechanical format.
1983 – The first formal VMEbus specification is released through the VMEbus Manufacturers Group (VMX). “VME” stands for VERSAmodule Eurocard.
Mid-1980s – VME gains traction across industrial, scientific, and military computing due to open architecture and multi-vendor support.
1987 – Officially adopted as IEEE 1014 standard, cementing VME’s position in embedded computing.
Early 1990s – VITA (VMEbus International Trade Association) leads continued development.
1994 – VME64 introduced: expands data path to 64-bit for faster throughput.
1997 – VME64x adds hot-swap capability, better connectors and shielding, geo-addressing and support for 3.3V and 5V signalling
2001 – 2eSST (Two-Edge Source-Synchronous Transfer) protocol published, allowing far higher transfer rates (up to ~320MB/s).
2000s – Ruggedised variants for defence and aerospace widely adopted; becomes a core architecture in naval, air, and rail control systems. Emergence of VPX (a high-speed serial successor) begins to attract new designs, but VME continues due to its long-term lifecycle support.
2010s - VME remains essential for military and aerospace platforms with 20+ year deployment cycles, industrial control, power stations, scientific instruments, and transport and situations where continuity and backward compatibility matter more than cutting-edge bandwidth
Manufacturers begin releasing modern CPU boards with contemporary processors (Intel, PowerPC, ARM) while retaining the VME form factor so old systems can be upgraded without redesigning the entire backplane.
2020s – Although VPX, CompactPCI Serial, and other serial-based architectures dominate new designs, VME continues to be supported, maintained, and manufactured, favoured for mission-critical systems with strict reliability and certification requirements
VME bus standard
The VME specification, owned by the VITA standards body, defines the electrical and mechanical system characteristics required to design boards that reliably and unambiguously communicate with other VME boards.
Architecturally, VME was based on the VERSAbus developed by Motorola in the 1970s, which used the Eurocard mechanical standard for printed circuit boards (PCBs). VERSAbus-E, as it was known, evolved into VMEbus and was approved by the Institute of Electrical and Electronics Engineers (IEEE) as IEEE 1014 in 1987.
The IEEE 1014 standard – which can be read here – “specifies a high-performance backplane bus for use in microcomputer systems that employ single or multiple microprocessors”.
VME’s system architecture was designed to optimise cost and performance without affecting compatibility, meaning that engineers could (and still can) scale and adapt systems using boards from various suppliers.
VME leverages the 6U Eurocard form factor – measuring 233.35mm by 160mm – providing ample space for I/O connectors on the front or rear. Although a 3U VME chassis standard existed, it never gained widespread adoption; 6U remains the predominant form factor.
Optimised for control functions
Our VME processor boards support the popular VME64 topology with MBLT transfers achieving up to 40 MB/s transfer rates. While this may seem slow compared with modern standards, it is important to remember that VME is typically not a high-bandwith data pipe, but a control channel.
VME systems typically use the VMEbus interface for basic setup and control functions, while front panel Gigabit Ethernet connections are used to support higher bandwidth communications between system elements.
This makes VME ideal for functions such as control and testing, for example in aircraft avionics.
It’s extremely easy to set up multiprocessing systems based on our VME processor boards, which can be configured to act as the System Controller for bus arbitration, a VME master supporting off board accessible memory, or a VME secondary board.
VME benefits
As mentioned earlier, defence systems can remain in service for many years, making VME central to mid-life upgrades and lifecycle extensions for legacy embedded systems.
The ability to drop a new VME processor board into a platform’s existing architecture – with minimal hardware and software changes – is significant for armed forces, reducing project risks and costs.
To support typical defence applications, Concurrent’s VME boards are designed and tested to operate reliably in harsh environmental conditions, including vibration, shock and extended temperature ranges.
VME can be a cost-effective solution for I/O based systems that do not require high throughput transfers, such as control and monitoring systems for naval vessels.
Our VME solutions
At Concurrent, we continue to invest in VME technology and have outlined a roadmap demonstrating our long-term commitment to this tried-and-tested technology.
VME remains a well-supported and widely installed bus standard, particularly in the defence market. We offer a range of Intel® processor-based VME boards designed for long life-cycle applications. These high-performance processor boards are complemented by switch fabric boards, XMC and PMC carriers, and mass storage modules.
Our latest VME solution, the Rhea board, offers modern performance by leveraging the newest Intel® Atom processor within a legacy-compatible form factor. This solidifies Concurrent’s position as a leading supplier of modern VME boards for specialist markets, including defence-a position that we intend to maintain for many years to come.
Looking to upgrade legacy systems or support your existing VME infrastructure? Contact us today for specialist products and support.