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Modern motherboards may still include headers for serial, parallel and PS/2 ports because the Low Pin Count interface and Super I/O chips preserved support for older hardware. Intel made the LPC specification open and royalty-free, and the hardware remains useful for system monitoring and control, so removing it can cost more than retaining it. The account does not identify a new motherboard announcement or a change to licensing.

Motherboards still include support for serial, parallel and PS/2 connections because the circuitry behind those legacy ports remains useful and inexpensive to retain, according to an XDA Developers report published October 24, 2026. The design traces back to Intel’s Low Pin Count (LPC) interface, whose open, royalty-free specification helped hardware makers adopt it as a replacement for the more pin-intensive ISA bus.

Intel introduced LPC in the 1990s as a lower-pin-count alternative to the Industry Standard Architecture (ISA) bus. The goal was to reduce the space, cost and testing burden associated with older hardware connections. Intel also made the specification open to the industry, allowing manufacturers to use the technology without paying royalties. That licensing approach helped encourage adoption, XDA reports.

LPC gave Super I/O chips a connection to the rest of the system. Manufacturers including Nuvoton, ITE and Winbond used the interface for chips that support legacy devices such as COM serial ports, LPT parallel ports, PS/2 peripherals and floppy drives. Those chips also handle functions that remain relevant today, including reading temperature sensors and controlling fan speeds.

The same interface later supported TPM 1.2, a cryptographic coprocessor developed by the Trusted Computing Group. The report says LPC suited the chip because it did not require much bandwidth, and the existing bus avoided added licensing costs. TPM 1.2 eventually lost favour over a security weakness: the report says data was sent unencrypted, allowing someone with physical access and suitable equipment to capture decryption keys. That issue did not, by itself, make the wider LPC hardware unnecessary.

Why Old I/O Still Fits

The continued presence of legacy headers reflects a cost and design trade-off, not necessarily a failure by manufacturers to update motherboards. The Super I/O chip still performs practical system-management tasks, while its legacy connections can remain available for users who need older peripherals or specialized equipment.

According to XDA, much of the logic supporting these connections is already part of the Super I/O chip. Removing the headers and stripping out the related capability could take more engineering work than leaving the connections in place. Retaining them may also avoid compatibility problems for older tools, including legacy digital-rights-management systems. The result is that a feature used less often can persist when removing it offers little benefit.

The licensing history helps explain how the arrangement became widespread. Intel’s royalty-free LPC specification lowered a barrier for manufacturers adopting the interface. Once it was incorporated into motherboard designs and connected to Super I/O functions, keeping the hardware became a straightforward choice. That does not mean every motherboard exposes every legacy port as a connector; the report describes support and headers that can appear on boards, not a universal layout.

From ISA to LPC

In the 1990s, Intel sought to move hardware makers away from ISA, which required more pins. LPC was designed to carry the relevant communication using fewer pins, reducing the demands on motherboard space and manufacturing. Intel’s decision to open the specification made it easier for other companies to build compatible hardware and integrate the interface into their own products.

Jan Camps, then a marketing manager for Intel’s Platform Component Division, described the goal as reducing the burden of older technologies while speeding access to higher-performing systems. Camps said Intel had opened the specification so the industry could adopt it and integrate it into motherboard legacy I/O development. XDA uses that statement to explain the licensing rationale behind LPC’s spread.

By the early 2000s, LPC was still used for legacy peripheral support, but its role had expanded. The Trusted Computing Group used the established interface for TPM 1.2, adding another reason for the bus to remain part of PC designs. The current explanation is therefore a matter of technical continuity: an interface built for a transition away from ISA continued to support other functions.

Which Boards Expose These Ports

The report does not provide a survey of current motherboard models, quantify how many still expose legacy headers, or establish that every modern PC supports every listed port. Header availability can vary by board design. It also does not give a specific cost estimate for removing the Super I/O functionality, so the comparison between retaining and removing it is described qualitatively.

The account explains the historical role of LPC and TPM 1.2, but it does not announce a new Intel licensing decision, a newly discovered vulnerability, or a change in motherboard policy. Its explanation of the TPM 1.2 security weakness is limited to the claim that unencrypted data could be captured by someone with physical access and a logic analyzer; it does not assess the security of all TPM versions or current systems.

Legacy Support Remains Board-Specific

No product launch, standards change or scheduled next step is identified in the report. For buyers, the practical next step is to check a motherboard’s manual and specifications if a COM, LPT or PS/2 connection is needed; the presence of a Super I/O chip does not guarantee that a particular port is exposed on the board.

Whether these headers disappear over time will depend on manufacturers’ board designs and the costs of changing established circuitry. The report’s explanation suggests there is little pressure to remove support while the chip remains useful for monitoring and control and the legacy capability is inexpensive to retain. It does not set out a timeline for a shift away from LPC or identify a replacement date.

Key Questions

Why do modern motherboards still support serial, parallel and PS/2 ports?

Those connections are handled through Super I/O chips that also perform current system tasks, including temperature monitoring and fan control. Retaining legacy support can be easier than removing the related hardware and logic.

What was Intel’s LPC interface designed to do?

Low Pin Count (LPC) was introduced as a lower-pin-count alternative to ISA. Intel aimed to reduce space, cost and testing demands, and made the specification open to industry adoption.

Did licensing help LPC become widely used?

Yes. XDA’s account says Intel made the LPC specification royalty-free, lowering the cost barrier for manufacturers adopting the interface and building compatible hardware.

Does every current motherboard have these legacy headers?

The report does not say that every board exposes every legacy connection. Availability varies by motherboard, so buyers should check the specific board’s manual and specifications.

What happened to TPM 1.2 over LPC?

The report says TPM 1.2 used LPC because it needed little bandwidth and the bus was already available. It later fell out of favour after a security weakness involving unencrypted data that could be captured with physical access and suitable equipment.

Source: XDA Developers