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Usually, no measurable slowdown can be assumed—but there is no universal latency figure. “USB-to-PS/2 adapter” can mean a passive plug that requires a dual-protocol keyboard, or an active converter that translates USB HID reports into PS/2 scan codes. The keyboard, adapter design, host firmware, and workload determine the result. For ordinary typing, any difference is unlikely to be noticeable; for latency-sensitive use, test the exact combination rather than relying on the connector shape or a generic number.
First identify what “PS/2 adapter” means
A six-pin PS/2 plug that fits the socket does not prove that a USB keyboard will work. Two fundamentally different products are sold under similar names:
Passive dual-protocol adapter
A passive plug contains no protocol translator. It simply routes signals and depends on a keyboard that was designed to support both USB and PS/2 signaling. If the keyboard only speaks USB, the adapter cannot make it compatible. When the keyboard does support both modes, the host is effectively using the keyboard’s PS/2 interface rather than converting USB data in the adapter.
Active USB-to-PS/2 converter
An active converter contains electronics and firmware that receive USB HID reports and emit PS/2 scan codes. Compatibility depends on the conversion direction, the keyboard’s USB implementation, and which keys and rollover features the converter understands. A manufacturer datasheet such as TRENDnet’s TU-PS2 documentation establishes this product category, but it does not establish current availability, universal keyboard support, or a latency advantage.
#1 Best Overall
- PS/2 to USB ADAPTER: Premium computers accessories - PS2 to USB adapter - compatible for PS2 Keyboard/ PS2 Mouse/ Windows/ Mac/ Linux/ Bar Code Scanner
- CABLES INTERCONNECTS FUNCTIONAL: USB to ps2 adapter with two PS2 female ports, PS2 mouse and keyboard through USB port on any computer
- USAGE: PS2 adapter to usb is compliant with the Standard Specification of USB 1.0 and 1.1. Purple port for keyboard and green one for mouse
- CONVENIENCE: PS/2 to USB converter converts two PS/2 devices (Keyboard and Mouse) to the USB Interface
- COMPATIBILITY: PS2 USB adapter keyboard converts the PC PS/2 port of KVM switch to USB port (PC or SUN platforms
Before troubleshooting speed, check the product description for whether the device is passive or active, the supported conversion direction, listed keyboard models or protocols, and known limitations.
Why USB and PS/2 can have different timing
USB keyboards are host-polled: the computer asks the device for reports at intervals. Belkin’s January 2026 support documentation identifies 125 Hz, or an 8 ms interval, as a common USB keyboard polling rate. That is a typical value in a manufacturer support article, not a guaranteed specification for every keyboard and not an end-to-end latency measurement.
Rank #2
- PS/2-to-USB ADAPTER: Adapter for those who like to continue using their PS/2 devices. Connect mouse and keyboard to your computer by using only one USB port
- SUITABLE FOR PS/2 DEVICES: Two PS2 female ports, purple for keyboard and green for mouse, and one USB male port.
- BUILT-IN USB-IC: You can use PERIPRO-401 to connect your keyboard and mouse with PS2 interface to USB 2. 0 port at PC or laptop. It also supports PS/2 Port of KVM Switch.
- UNIVERSAL PURPOSES: Fits with industrial and professional needs
- PACKAGE INCLUDES: Perixx PERIPRO-401 adapter, manual; 12-month limited
PS/2 uses a device-driven serial exchange rather than USB polling. In a 2014 project describing his own PS/2-to-USB converter, Nicolas S. Dade wrote: “I like the low latency of PS/2 (~1 msec for DOWN, ~2 msec for UP).” The same author described 10 ms as a typical USB keyboard polling interval and increased the interval rate in his converter firmware to reduce USB-side waiting. Those figures characterize his design and experience; they are historical, implementation-specific statements, not a benchmark for all keyboards or adapters.
Even an 8–10 ms report interval does not mean every keystroke is delayed by that full amount. The actual time depends on when a key event occurs relative to the next USB poll, firmware buffering, operating-system scheduling, the application, and display or game processing. A converter can add its own buffering or translation delay, while a poor implementation can affect correctness rather than merely add a fixed delay.
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Rank #3
- [Package Contents] Includes four adapters (4.3*1.8 cm / 1.7*0.7 inch). These adapters are compatible with most PS/2 interface mice and keyboards. Only mice or keyboards with built-in chip converters will work; please check compatibility before purchasing.
- [USB to PS/2 Adapter] This USB to PS/2 adapter allows you to easily connect a USB mouse or keyboard to a computer with limited USB ports. Note that the resulting USB port can only be used to connect a mouse and keyboard; other USB devices cannot be connected.
- [Driver-Free Installation] This adapter features a plug-and-play design, requiring no software drivers. Simply plug your mouse or keyboard into a PS/2 port to use your device without any additional setup, ensuring a hassle-free and convenient experience.
- [Instructions] The PS/2 to USB adapter is not hot-swappable, so be sure to turn off your computer before connecting the adapter. After connecting, please restart your computer. If the middle mouse button becomes unresponsive, simply restart your computer for optimal performance.
- [Wide Application] This adapter is ideal for computers with insufficient USB ports or malfunctioning USB devices. By converting a USB port to a PS/2 connection, you can ensure stable use of your mouse or keyboard without taking up valuable USB ports, thereby enhancing the functionality of your device.
What Windows does with each connection
Microsoft documents separate input paths. For USB keyboards, KBDHID.sys maps HID usages to scan codes for the keyboard class driver, while HIDCLASS connects HID clients to their transport. PS/2-style keyboards use the I8042prt path. Microsoft’s description—“KBDHID.sys: HID client mapper driver for keyboards. Converts HID usages into scan codes to interface with the existing keyboard class driver.”—describes architecture, not a measured speed difference.
An active adapter must perform a comparable mapping itself. Microsoft’s USB HID-to-PS/2 scan-code table shows why this is not a simple electrical change: USB usages and PS/2 scan codes are different code sets. Unsupported mappings, firmware bugs, or limited buffers can cause missing keys, incorrect special-key behavior, or rollover problems.
Rank #4
- 【USB to Dual PS/2 Adapter】 Convert a single USB port into two PS/2 ports. This adapter allows connection of one PS/2 keyboard and one PS/2 mouse to a computer that only has USB ports.
- 【Connect Keyboard and Mouse】 Designed with two PS/2 female ports (purple for keyboard and green for mouse), allowing connection of legacy PS/2 input devices to modern computers with USB ports.
- 【Broad OS Compatibility】 Works with most operating systems including Windows, Linux, and other systems that support standard USB keyboard and mouse devices.
- 【Ideal for Legacy Peripherals】 A practical solution for using older PS/2 keyboards and mice with PCs or laptops that lack PS/2 ports. Suitable for home, office, and legacy hardware setups.
- 【Passive Adapter – Compatibility Notice】 This is a passive adapter and requires devices that support both USB and PS/2 protocols (dual-mode devices). It will not convert PS/2-only devices to USB.
What can actually go wrong
| Area | Native supported connection | Adapter-dependent risk |
|---|---|---|
| Basic key presses | Handled by the keyboard’s intended protocol path. | Active translation may buffer or mis-map reports; passive adapters fail if the keyboard lacks dual-protocol support. |
| Key release events | Normally delivered by the native interface. | A project author reported missed releases with two adapters he tried. This is an individual report, not a general defect rate. |
| Simultaneous keys and rollover | Limited by the keyboard and native controller. | Converter firmware may support fewer simultaneous keys than the keyboard advertises. |
| Media and special keys | Depends on the operating system and keyboard. | USB usages without a PS/2 equivalent may be ignored or translated inconsistently. |
| Latency evidence | Can be measured for the exact keyboard and port. | No universal adapter-latency value is established; implementation and polling settings matter. |
How to check your own setup
Use the following sequence if you are trying to determine whether an adapter causes delay or degraded behavior:
- Verify compatibility. Confirm whether the device is a passive dual-protocol plug or an active USB-to-PS/2 converter, and check its stated direction and keyboard support.
- Check ordinary operation. Test every alphanumeric key, modifiers, Backspace, Enter, and both Shift keys. Confirm that each key registers on press and stops registering on release.
- Test combinations. Hold several keys at once, including the combinations you use in games or shortcuts. Check for ghosting, dropped keys, or stuck keys.
- Test special functions. Try function-row shortcuts, media controls, navigation keys, and any programmable keys. A converter may pass standard keys while omitting uncommon USB usages.
- Compare a native path. Use the same keyboard, computer, software, and workload on a directly supported connection. Change one variable at a time; otherwise you cannot attribute a difference to the adapter.
- Measure only if it matters. Use a repeatable key-to-response or electrical latency method and record the keyboard model, adapter, port, operating-system version, and polling configuration. Do not generalize that result to another adapter or keyboard.
Should you expect a noticeable slowdown?
Office work and general typing
For typing, navigation, and shortcuts, a small polling interval is normally below conscious detection, provided key presses and releases are reliable. A converter that drops releases or fails to support required keys is a practical problem even if its average delay is small.
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- ✪ COST EFFECTIVE. it will allow you to use your old keyboard with your new computer that will only support USB interfacing. Nice way to extend the usefulness of older high-quality and favorite keyboards.The adapter allowed you to use an old keyboard and helps to avoid some unnecessary landfill.Highly recommend it if you want to bring old keyboards back to life.
- ✪ COMPATIBILITY. It works perfectly even with very old keyboards. it allows you to reuse the old setup with a full PS2 KVM. It works with both Linux and Win. Old keyboards and mice that lay in the cellar can prove useful again.
- ✪ RECOGNIZED INSTANTLY.It is able to connect the keyboard and mouse to it and plug it all into the usb port that immediately detects the device.Works speed perfectly . Connect a mouse and keyboard to a laptop perfectly well and got recognized as soon as you booted.Works without lag.
- ✪ A QUALITY ITEM.Have a USB chip in it。Plugging it into the kvm cables was easy nice solid fit. The quality of the adapter appears to be well made and sturdy. Blue for keyboard, green for mouse.The build of the device is a lot better than most. It has that block in the middle of the cable.the adapter is rugged enough to last for years and years.
- ✪ SIMPLE PLUG AND PLAY.Worked straight out of the box. No configuration, installation or settings needed. Just plug in and type away. Perfect.does exactly what I wanted it to do.
Competitive gaming or instrument-like timing
Latency-sensitive users should prefer a native, documented connection when available, or validate the adapter with the exact game and keyboard. The available sources do not provide a controlled head-to-head test of a USB keyboard through a PS/2 adapter versus the same keyboard on native USB or native PS/2, so a claim that adapters are faster—or that they always slow a keyboard—is unsupported.
Legacy hardware compatibility
If an older computer accepts only PS/2 input, an active converter may be useful despite uncertain timing. Treat compatibility and reliable key events as the deciding criteria, not a presumed performance upgrade.
Quick Recap
Decision checklist
- Choose a passive adapter only when the keyboard explicitly supports USB and PS/2 modes.
- For an active converter, verify USB-to-PS/2 direction and supported keyboard features.
- Reject a setup that produces missed releases, stuck keys, dropped combinations, or unusable special keys.
- Use a native connection for latency-critical work when it is available and supported.
- When timing is important, measure the complete setup instead of quoting 125 Hz, 8 ms, 10 ms, or PS/2 estimates as guaranteed results.
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