The PC is rarely the most expensive part of a system, but it’s often the part that fails first, and the legacy interfaces it depends on are what make replacement difficult – and costly.
Recently, a construction provider called us after the industrial PC controlling one of their plant systems failed. The PC was over 15 years old, running Windows XP with a proprietary PCI add-on card from the plant manufacturer, and software locked to a parallel port dongle. Everything about the system was obsolete, but the plant itself was still perfectly functional and worth hundreds of thousands of dollars.
Their options came down to three choices: find someone who could build a replacement PC that supported the same card, the same dongle, and the same operating system, go back to the machine manufacturer and pay for an expensive control system upgrade, or replace the entire plant. The first option cost a few thousand dollars. The second cost tens of thousands. The third cost significantly more.
It’s a scenario we see regularly across Australian industry. So what interfaces are still available in 2026, and what can action can you take to avoid expensive consequences if PCs fail?
ISA slots are nearly gone
ISA expansion slots were standard in industrial PCs through the 1990s and into the early 2000s. Many machines from that era shipped with a proprietary ISA I/O card that the control software depends on. There is no PCIe equivalent. There is no USB equivalent. Without the ISA slot, the card cannot be used, and without the card, the software does not work.
No mainstream industrial motherboard manufacturer still produces boards with ISA slots. The only practical solution in 2026 is a passive backplane system using a PICMG 1.0 CPU card, which provides both ISA and PCI slots in a backplane chassis. We have built these systems by combining components from multiple vendors to create a working configuration that also supports Windows XP.
But the window is closing. Stocks of compatible backplane boards, CPU cards and the processors and RAM they require are running out. We can still build these systems today, but we cannot guarantee availability for much longer. If you have a critical system that depends on an ISA card, securing replacement hardware now while components are still available is the most practical advice we can offer.
PCI slots are still available, but for how long?
32-bit PCI slots are in a better position than ISA, but the trend is clearly downward. Many current industrial motherboards and backplanes still include PCI slots, and some fanless industrial PCs offer them as well. For now, replacing a system that depends on a legacy PCI card is usually achievable.
The CyberVisuell CYBOX-AE7DL, for example, is a fanless industrial PC with 6th and 7th generation desktop Core CPUs and two expansion slots that can be configured as one PCIe and one PCI. This makes it a practical option for systems that need a legacy PCI card alongside a current operating system, with Windows 7 and Windows 10 both supported.
However, PCI is following the same trajectory ISA did a decade ago. Fewer boards support it with each new chipset generation. If your operation depends on PCI expansion cards, it’s worth understanding which of your systems are affected and planning accordingly, rather than assuming PCI will be available indefinitely.
Parallel ports now mostly a dongle problem
Parallel ports have largely disappeared from industrial motherboards and single board computers. In most cases, the only reason a parallel port is still needed is a software licence dongle that plugs into it.
The practical solution is a PCI or PCIe parallel port card, which are still readily available and generally work reliably with parallel dongles. USB-to-parallel adapters are sometimes suggested as an alternative, but these are primarily designed for connecting parallel printers and have known compatibility issues with licence dongles. If your system depends on a parallel port dongle, a native PCI or PCIe parallel card is the safer path.
Where possible, it is also worth contacting the software vendor to ask about alternative licensing. Some vendors have moved to USB dongles or software-based licensing for newer versions. If an upgrade path exists, it removes the parallel port dependency entirely.
Serial ports are the one that still works
Unlike ISA, PCI, and parallel, RS-232 and RS-485 serial ports remain well supported across current industrial PC hardware. Most industrial motherboards, fanless PCs and panel PCs include native serial ports, often with configurable RS-232 and RS-485 modes.
For systems that need more serial ports than the motherboard provides, USB-to-serial adapters are widely available in industrial-grade versions, including USB to RS-485 converters. Most modern software supports USB serial ports without issues, making this one of the easier legacy interface requirements to satisfy.
The CyberVisuell TBOX-12310 is a popular choice for applications needing multiple serial ports alongside legacy operating system support. Its J1900 processor supports Windows 7 and 10, and it includes multiple RS-232 and RS-485 ports natively, which makes it well suited to legacy SCADA, data acquisition and industrial communication applications that still depend on serial connectivity.
If your system communicates with PLCs, instruments or other devices over serial, this is unlikely to be the interface that causes you problems during a hardware replacement. Serial is the one legacy interface the industry has continued to support.
The real decision – to replicate or migrate
When an industrial PC with legacy interfaces fails, the immediate instinct is to replicate the existing system as closely as possible. That is often the right short-term decision. It gets the plant running again quickly and avoids the cost and risk of changing the software environment.
But replication gets harder and more expensive with every passing year as components become scarcer. At some point, the cost of finding and assembling legacy-compatible hardware exceeds the cost of migrating to a current platform.
The practical approach is to do both in sequence. Replicate now to restore production, then use the breathing room to plan and budget for a migration that eliminates the legacy dependency. This might mean working with the machine manufacturer to upgrade the control system, replacing the proprietary I/O card with a modern equivalent or moving to current software that runs on standard hardware.
The worst outcome is doing neither: failing to secure legacy replacement hardware while it’s still available, and failing to plan a migration while there is time to do it properly.
How ESIS can help
We have extensive experience building industrial PCs for legacy interface requirements, from passive backplane systems with ISA and PCI slots running Windows XP, through to current fanless PCs with native serial ports and PCI expansion. We understand the compatibility constraints and can advise on what is still achievable and what isn’t.
If you have critical systems that depend on legacy I/O cards, dongles or older operating systems, we can help you assess your current hardware, source compatible replacements while components remain available and plan for the eventual transition to current technology.
Please contact us to discuss your needs.
ESIS Industrial Electronics offers a range of industrial computing solutions, including rugged tablets, data loggers, industrial displays, integrated computing platforms and programmable interfaces for direct PLC integration. Talk to us about your project requirements and solutions to keep business operations running efficiently.
