4 ms·

I hope not! Because systems like PS/2, COM/Serial ports, etc are really simple and well-understood (compared to USB) which does make them more reliable or depen

I hope not! Because systems like PS/2, COM/Serial ports, etc are really simple and well-understood (compared to USB) which does make them more reliable or dependable in situations where it matters. Additionally, PS/2 is very much still used today: every laptop I've ever owned, including my brand-new 2024 ThinkPad P1, has a touchpad ostensibly using a PS/2 connection internally - and we get all this functionality essentially for free (yay lithography): it's all baked into a single "Super I/O" unit[1] which today is part of some larger IC on your mobo. ...that said, Microsoft and some hardware partners tried this when Windows XP came out; they were called "Legacy-free PCs", which in-practice just meant (excepting video and audio) all periphial ports were USB 1.1, with zero (exposed) ports for PS/2, parallel, serial, ISA, and gameport/MIDI; no floppy drive either; it was also a convenient excuse to omit a 56K modem too. (Anyone remember the iPAQ Desktop[2]?). ...but it was more style than substance: those computers were still x86 machines using the same mobo chipsets as a traditional box, so the hardware support for PS/2 and the like was still there in the chips, just without the traces connected to anything and the functionality disabled via BIOS settings or maybe something like an e-fuse. [1] https://en.wikipedia.org/wiki/Super_I/O https://en.wikipedia.org/wiki/Super_I/O [2] https://en.wikipedia.org/wiki/IPAQ_(desktop_computer) https://en.wikipedia.org/wiki/IPAQ_(desktop_computer)

shiroiushi 2y ago
That's very interesting, but what's the purpose of installing PS/2 ports on modern motherboards when no one uses them? It's a waste of money and materials and space, and just contributes to e-waste. I can see leaving them in equipment made for certain specialty/embedded applications, but not mainstream consumer equipment. I also wonder how much power those "super I/O" chips are wasting with this unused circuitry. And why is PS/2 internally used for touchpads anyway? Inertia? There's plenty of perfectly good serial protocols out there for these kinds of low-speed serial I/O applications, such as SPI.
- DaiPlusPlus 2y ago
  (I wrote a long reply to this post with technical details; then I accidentally reloaded the tab in Chrome and it lost my textarea text and it's 3am here so argh). But to briefly summarize when I did write: > installing PS/2 ports on modern motherboards I haven't seen a PS/2 port on any brand-new (non-industrial) computer, even rackmount servers, since 2009. My own last mobo with PS/2 ports was bought in 2008; I haven't seen PS/2 on a laptop since 2003. > and just contributes to e-waste e-waste is a problem, yes; but PS/2 ports are really, really, not a meaningful cause of any problems in this area. > I also wonder how much power those "super I/O" chips are wasting with this unused circuitry. Zero. ICs (mostly) consume power only when their transistors undergo a state-change. If the PS/2 microcircuitry in an IC is never used, then there won't be any concordant transitor state-changes, ergo, there won't be any (measureable) power-draw. This is why microprocessor lithography is great: you really do get stuff for free. > why is PS/2 internally used for touchpads anyway? I wrote "ostensibly"; in reality, it usually isn't actually "PS/2" as-we-know-it, but is some other protocol over I2C or even SPI as you suggested (e.g. Synaptics calls theirs "InterTouch"[1]), but the hardware-interface that the OS uses is compatible with Intel's i8042 which was the original PS/2 ( https://wiki.osdev.org/%228042%22_PS/2_Controller https://wiki.osdev.org/%228042%22_PS/2_Controller ) even though the i8042 no-longer exists today. [1] https://investor.synaptics.com/news-releases/news-release-details/synaptics-announces-groundbreaking-intertouch-touchpadtm https://investor.synaptics.com/news-releases/news-release-de... ----- As for why practically every laptop seems to use "PS/2" for their touchpads today, I speculate that laptop OEMs prefer this "PS/2-a-like" for 2 reasons: 1. Consumes less power (and with far less overhead overall) compared to an internal USB connection, which is important in a laptop computer. 2. Laptops likely only have a single USB root controller, which is usually for the latest USB revision when the laptop was engineered - so a new laptop today likely has only a USB4 controller, which will be backwards-compatible with older USB devices, but you'll have issues if you need to use an OS or EFI application (e.g. BIOS Setup utility, Bitlocker manual unlock screen, custom boot-manager, etc) due to spotty support for future USB controllers, so it makes sense to ensure that the laptop's fundamentally-essential input devices (i.e. mouse and keyboard) are connected via a mature, widely-supported interface like the i8042's) to avoid the laptop becoming completely unusable if something goes wrong with USB support (because it's not like you'll be able to plug-in an external USB mouse/keyboard and expect that to work...). Whereas on desktops I've noticed that whenever there's support for some cutting-edge USB revision (e.g. USB 3.x in 2012ish or USB4 today) the board will have a couple of USB 2.0 ports via a different controller, so you won't be SOL if anything goes wrong with the new stuff.
  - shiroiushi 2y ago
    >I haven't seen a PS/2 port on any brand-new (non-industrial) computer, even rackmount servers, since 2009 They're in lots of B550 chipset (AM4 socket) motherboards. Here's some examples: https://www.amazon.co.jp/-/en/gp/B089Y9PFH1 https://www.amazon.co.jp/-/en/gp/B089Y9PFH1 (ASUS Prime B550M-A) https://www.amazon.co.jp/-/en/gp/B0CXNK17WT https://www.amazon.co.jp/-/en/gp/B0CXNK17WT (MSI B550M PRO-VDH) https://www.amazon.co.jp/-/en/dp/B089W26FCB https://www.amazon.co.jp/-/en/dp/B089W26FCB (AsRock B550M-HDV) https://www.amazon.co.jp/-/en/dp/B08MXSQS49 https://www.amazon.co.jp/-/en/dp/B08MXSQS49 (AsRock B550M Phantom Gaming 4) Granted, these are a generation old and not the latest AM5 socket stuff, but still AM4 chips are fairly popular; these motherboards probably all came out around 2019. >e-waste is a problem, yes; but PS/2 ports are really, really, not a meaningful cause of any problems in this area. It all adds up. Millions upon millions of never-used PS/2 across all these systems for the many years these motherboards have been manufactured is a big pile of PS/2 connectors, all gone to waste.
- kbolino 2y ago
  Some USB keyboards and mice, and some ways of plugging them into the system, can result in noticeable issues like key ghosting and input lag. Thus some people still kept around their PS/2 devices and avoided USB adapters. This is mostly not a problem nowadays. The issues arose from cheaper/poorly implemented devices and the use of hubs (both internal and external) to provide more ports.

shiroiushi 2y ago

That's very interesting, but what's the purpose of installing PS/2 ports on modern motherboards when no one uses them? It's a waste of money and materials and space, and just contributes to e-waste. I can see leaving them in equipment made for certain specialty/embedded applications, but not mainstream consumer equipment. I also wonder how much power those "super I/O" chips are wasting with this unused circuitry. And why is PS/2 internally used for touchpads anyway? Inertia? There's plenty of perfectly good serial protocols out there for these kinds of low-speed serial I/O applications, such as SPI.

DaiPlusPlus 2y ago
(I wrote a long reply to this post with technical details; then I accidentally reloaded the tab in Chrome and it lost my textarea text and it's 3am here so argh). But to briefly summarize when I did write: > installing PS/2 ports on modern motherboards I haven't seen a PS/2 port on any brand-new (non-industrial) computer, even rackmount servers, since 2009. My own last mobo with PS/2 ports was bought in 2008; I haven't seen PS/2 on a laptop since 2003. > and just contributes to e-waste e-waste is a problem, yes; but PS/2 ports are really, really, not a meaningful cause of any problems in this area. > I also wonder how much power those "super I/O" chips are wasting with this unused circuitry. Zero. ICs (mostly) consume power only when their transistors undergo a state-change. If the PS/2 microcircuitry in an IC is never used, then there won't be any concordant transitor state-changes, ergo, there won't be any (measureable) power-draw. This is why microprocessor lithography is great: you really do get stuff for free. > why is PS/2 internally used for touchpads anyway? I wrote "ostensibly"; in reality, it usually isn't actually "PS/2" as-we-know-it, but is some other protocol over I2C or even SPI as you suggested (e.g. Synaptics calls theirs "InterTouch"[1]), but the hardware-interface that the OS uses is compatible with Intel's i8042 which was the original PS/2 ( https://wiki.osdev.org/%228042%22_PS/2_Controller https://wiki.osdev.org/%228042%22_PS/2_Controller ) even though the i8042 no-longer exists today. [1] https://investor.synaptics.com/news-releases/news-release-details/synaptics-announces-groundbreaking-intertouch-touchpadtm https://investor.synaptics.com/news-releases/news-release-de... ----- As for why practically every laptop seems to use "PS/2" for their touchpads today, I speculate that laptop OEMs prefer this "PS/2-a-like" for 2 reasons: 1. Consumes less power (and with far less overhead overall) compared to an internal USB connection, which is important in a laptop computer. 2. Laptops likely only have a single USB root controller, which is usually for the latest USB revision when the laptop was engineered - so a new laptop today likely has only a USB4 controller, which will be backwards-compatible with older USB devices, but you'll have issues if you need to use an OS or EFI application (e.g. BIOS Setup utility, Bitlocker manual unlock screen, custom boot-manager, etc) due to spotty support for future USB controllers, so it makes sense to ensure that the laptop's fundamentally-essential input devices (i.e. mouse and keyboard) are connected via a mature, widely-supported interface like the i8042's) to avoid the laptop becoming completely unusable if something goes wrong with USB support (because it's not like you'll be able to plug-in an external USB mouse/keyboard and expect that to work...). Whereas on desktops I've noticed that whenever there's support for some cutting-edge USB revision (e.g. USB 3.x in 2012ish or USB4 today) the board will have a couple of USB 2.0 ports via a different controller, so you won't be SOL if anything goes wrong with the new stuff.
- shiroiushi 2y ago
  >I haven't seen a PS/2 port on any brand-new (non-industrial) computer, even rackmount servers, since 2009 They're in lots of B550 chipset (AM4 socket) motherboards. Here's some examples: https://www.amazon.co.jp/-/en/gp/B089Y9PFH1 https://www.amazon.co.jp/-/en/gp/B089Y9PFH1 (ASUS Prime B550M-A) https://www.amazon.co.jp/-/en/gp/B0CXNK17WT https://www.amazon.co.jp/-/en/gp/B0CXNK17WT (MSI B550M PRO-VDH) https://www.amazon.co.jp/-/en/dp/B089W26FCB https://www.amazon.co.jp/-/en/dp/B089W26FCB (AsRock B550M-HDV) https://www.amazon.co.jp/-/en/dp/B08MXSQS49 https://www.amazon.co.jp/-/en/dp/B08MXSQS49 (AsRock B550M Phantom Gaming 4) Granted, these are a generation old and not the latest AM5 socket stuff, but still AM4 chips are fairly popular; these motherboards probably all came out around 2019. >e-waste is a problem, yes; but PS/2 ports are really, really, not a meaningful cause of any problems in this area. It all adds up. Millions upon millions of never-used PS/2 across all these systems for the many years these motherboards have been manufactured is a big pile of PS/2 connectors, all gone to waste.
kbolino 2y ago
Some USB keyboards and mice, and some ways of plugging them into the system, can result in noticeable issues like key ghosting and input lag. Thus some people still kept around their PS/2 devices and avoided USB adapters. This is mostly not a problem nowadays. The issues arose from cheaper/poorly implemented devices and the use of hubs (both internal and external) to provide more ports.