Is a mouse better in PS/2 or USB

[Ninjo]

Does a mouse work better in a PS/2 port or in the USB port? Does it really matter? Does it make a difference in games?

 

[Peter]

Before the "PS/2 has adjustable poll rate" misconception turns up again: USB is a busmaster device on a fast chipset internal connection (faster than PCI), while PS/2 is on the ancient AT keyboard controller (an 8-bit ISA device).

This is why PS/2 needs that poll rate adjustment to keep balance between hogging the system busses for too long and making the mouse too jerky. USB lets you have a smoothly moving mouse cursor without using much bus time.

 

[konakona]

Originally posted by: Peter
Before the "PS/2 has adjustable poll rate" misconception turns up again: USB is a busmaster device on a fast chipset internal connection (faster than PCI), while PS/2 is on the ancient AT keyboard controller (an 8-bit ISA device).

This is why PS/2 needs that poll rate adjustment to keep balance between hogging the system busses for too long and making the mouse too jerky. USB lets you have a smoothly moving mouse cursor without using much bus time.

so is there a noticeable difference? my usb slots are completely full. if it isnt anything major i would continue using ps/2.

 

[dc5]

you won't notice the difference. i personally use the ps/2 slot so i'll have one more usb slot.

 

[KamiXkaze]

Unless you are doing alot of gaming with your mouse(doom 3,far cry,and HL2) or anything that requires using a high speed bus like USB(1 or 2)you will be ok!

 

[Maximus96]

I've noticed that when my mouse is plugged into the USB and when the cpu is under load, sometimes my mouse will skip. when i plug it into the ps/2 port, it doesn't do that. i've since left it in the ps/2. i have a mx510 btw.

 

[KBtn]

either or...just about the same for normal computer use. USB for gaming though

 

[Patt]

stick with the PS/2 ... for the difference you get with USB, not many people will notice it unless they're into some really intense game situations, and they're tuned to be watching mouse performance.

 

[wchou]

There is nothing wrong with PS/2, personally USB is for convenient and is rarely used by most people. Stores like Best Buy sells ps/2 exclusively. usb has to be specially ordered thought.

 

[VirtualLarry]

Originally posted by: Peter
Before the "PS/2 has adjustable poll rate" misconception turns up again: USB is a busmaster device on a fast chipset internal connection (faster than PCI), while PS/2 is on the ancient AT keyboard controller (an 8-bit ISA device).

Isn't the USB functionality provided by the vast majority of the chipsets out there, on the southbridge? Also, on my Via KT400/8235, at least, it's not in the least bit busmastering, it's PIO-driven. Second, there is no physical AT keyboard controller anymore, it's also integrated into the chipset, I'm guessing with the LPC I/O functionality, so it doesn't have exactly the same sorts of performance disadvantages that a real 8-bit ISA device would have. In short, both are chipset-internal in the southbridge on current machines, so both should have similar performance.

Originally posted by: Peter
This is why PS/2 needs that poll rate adjustment to keep balance between hogging the system busses for too long and making the mouse too jerky. USB lets you have a smoothly moving mouse cursor without using much bus time.

I've never, ever, seen a PS/2 mouse take up an excessive amount of CPU time. I would argue that exact opposite - with a (usually dedicated) IRQ line, and a much smaller software stack in the OS to handle PS/2 port activity, it is overall far more efficient than USB for input devices. USB has multiple levels of device-drivers, including some user-mode components that need to process the data (HIDSRV), and the latency involved for the OS to schedule all of those threads before the input is fully-processed - on a heavily-loaded machine, I find USB mice to lag and skip a lot, although that may be due to my PIO-mode USB chipset too. Even on a chipset that supported bus-master USB ports, even if the hardware is able to read the data in a fraction of time, if the system still has to wait to schedule a lower-priority user-mode process in order to "cook" the data before use, then it will still lag. This same phenomenon can also be observed with PS/2 mice, if one installs Logitech's MouseWare software, which allows re-mapping buttons, etc. The additional software-stack overhead is noticeable to gamers.

The original reason for allowing adjustment of the AT keyboard microcontroller's clock speed, was to overclock it and increase peformance (due to the discrete keyboard microcontroller being somewhat slow in executing/intepreting commands), it had nothing to do with bus utilization, which is utterly trivial. If you want to talk about wasteful bus utilization, how about onboard AC'97 audio chipsets that don't use bus-mastering, or only have a buffer the size of a single CPU cacheline, leading to "skippy" audio whenever something slightly CPU-heavy is being run, and the fact that it needs to be "fed" so often, precludes doing large PCI burst transfers over the same bus. (Heck, even ISA sound cards had at least a small internal sound-buffer FIFO, even if they weren't DMA-driven themselves.)

 

[Peter]

VL, yes the USB controller is a busmaster device. There are standards for that, UHCI, OHCI, EHCI. Read up.

And yes there still is a physical AT keyboard controller - either integrated into the Super-IO chip, or into the south bridge. It's connected to the LPC bus, which, being a 4-bit wide PCI-ish bus, is no faster than legacy ISA. It just uses a (L)ow (P)in (C)ount connection to get you the same kind of throughput as ISA did. No better. Worse actually, since the interrupt requests come in through a serial one-wire port rather than 15 parallel; signalling an interrupt from LPC down into the interrupt controller takes at least 21 PCI clocks. Lag galore ... and besides, the AT keyboard microcontroller is still there, still as slow, and still doing the exact same thing. It is still the same 1977-designed generic I/O controller, with the same ancient firmware, still hooked up as an 8-bit I/O device to a bus that doesn't look like ISA anymore but by all performance parameters still is.

Note that I said bus time, not CPU time.

AC97 audio uses bus mastering to fetch the stream data just as well. They may or may not use the CPU to _compute_ the resulting audio stream, but the final data pumping toward the codec is always DMA. Skippy audio as a result of too much CPU load is caused by a lack of computing power, not a lack of bus time. The latter problem often happens exactly with PIO mode accesses to subordinate busses (PCI, LPC) locking out southbridge-internal bus masters from winning the bus arbitration up to the north bridge. (More intelligent chipsets, like those from SiS with their multi-threaded I/O link between north and south, solve this problem by allocating one link thread to the sound engine.)

 

[oogabooga]

I use USB since i have plenty of USB slots, and my old mobo couldn't register the mouse and keyboard in both slots.

hardcore gamers will SWEAR by their mice, and will demand high resolution, high definition, and USB. I am not one of them, but i have the slot and use it. If it is convinient to, then go for it. IF not, then plug it into PS/2. If you notice problems, buy a hub, or a new mobo. My K8n-Neo FSR came with EIGHT usb ports, so *scratches head* i guess i need a couple more usb devices

 

[konakona]

it just got me wondering since all the accounts i have seen on the internet goes against what peter has suggested. the only case of possible input delay i know of is occasional CPU utilization spike reported by some USB users. i have never had any problem with PS/2 and gaming, but you know what they say... you never know what you are missing maybe USB is better, i couldnt tell when i was forced to go with the USB.

 

[archcommus]

I know this is dead but I'd like to comment, and it was never really resolved anyway. I just got an MX510, and although I was planning to use the USB connector, the manual said to use the PS/2 adaptor for desktops, and only to use the USB for laptops and Macs. So, I did. Should I switch to USB?

 

[madthumbs]

I notice a difference between the two in fps's. It seems like the frame rate is jerky when it's really the mouse on ps2 bus causing it. I think with higher resolutions it's more noticeable.

 

[BDawg]

I just can't imagine the bandwidth from a mouse matter much. I use USB for 2 reasons. 1. Convenience. I plug my mouse's base station into my monitor. 2. My old ABit motherboard had a problem with the mouse ps/2 port which would cause jerky movement.

 

[Mem]

I just got an MX510, and although I was planning to use the USB connector, the manual said to use the PS/2 adaptor for desktops, and only to use the USB for laptops and Macs. So, I did. Should I switch to USB?

Yes use USB,btw FYI the new Razer Diamondback gaming mouse is USB only,do you think Razer would design a gaming mouse for USB only if PS/2 was superior.

 

[JackMDS]

Originally posted by: Mem

I just got an MX510, and although I was planning to use the USB connector, the manual said to use the PS/2 adaptor for desktops, and only to use the USB for laptops and Macs. So, I did. Should I switch to USB?

Yes use USB,btw FYI the new Razer Diamondback gaming mouse is USB only,do you think Razer would design a gaming mouse for USB only if PS/2 was superior.

The reason is mainly economical. It is less expensive to design USB only since it is easy to port it cross platforms.

In addition, the PS/2 port is approaching End of Life, so many manufactures start to shy away from it on their new designs.

If the USB mouse is the only USB peripheral, it does not matter what you use. Otherwise, the PS/2 Mouse is much more stable.

However using PS/2 takes an IRQ.

So there is No General Best, there is Best according to the given situation.

:sun:

 

[Mem]

If the USB mouse is the only USB peripheral, it does not matter what you use. Otherwise, the PS/2 Mouse is much more stable.

Stability does depend on the hardware and setup etc...in my case I`ve USB printer,USB joypad,USB mouse,USB Keyboard,USB External DVD burner,USB 2.0 external 7 port Hub,USB thumbdrive and have no problems with that many devices connected all at once.

Infact I find using USB hardware to be 100% stable on both my PCs for the last 3 years.


I agree about PS/2 coming to its end life, also remember by default PS/2 is 40 or 60Hz depending on the OS used,compared to the 125Hz sampling rate for USB unless you use a PS/2 mouse rate tools program.

So there is No General Best, there is Best according to the given situation.

I guess you can argue it`s really personal preference,but I for one will stay with USB which has been solid IMH experience.

Another small advantage is hot swapping for USB devices.

PS/2 is on the ancient AT keyboard controller (an 8-bit ISA device)

I may be wrong, but the Razer Diamondback is designed has a 16bit mouse,so is that why it`s not PS/2?.

 

[archcommus]

You sure PS/2 is approaching the end? Doesn't seem like it to me. Even the newest of the new motherboards have it. Even Shuttles, which strip away whatever they can get away with, have it. Even that old Abit motherboard that pretty much had only USB ports had it. I think manufacturers like to use them as the standard for input devices, whether people are actually using them or not. Makes it easier for the mainstream users (i.e. not us), to tell them to use those little round green and purple ports for your keyboard and mouse.

In summary I don't expect to see it removed anytime soon.

I also can't see it making that much of a difference. I mean, mice aren't really transmitting GBs of information or anything. I've been gaming since I hooked up my MX510 with both the PS/2 and USB and have noticed no difference so far. And if I move the mouse as fast as I possibly can on the deskop it actually feels a BIT quicker when hooked up to PS/2. This probably isn't true, though, it's really hard to tell. I honestly think it's the same.

So all in all, I don't think it matters. If I ever experience jerkiness in a game when I don't think I should be, I'll give the USB connector a shot (which is what I've been using for the past three years with my IntelliMouse). But until that happens (if it happens), I really don't see a reason to switch. I keep a free USB port open this way, too. My mobo has four in the back and two in the front. I don't want to hook up permanent things in the front, nor do I want to have to add a PCI card or an external hub. I have a USB scanner, printer, and external hard drive, so if I hook up my mouse via USB, they're all full.

 

[madthumbs]

I also can't see it making that much of a difference. I mean, mice aren't really transmitting GBs of information or anything

-It's not about bandwidth, it's more about sample rates, or hertz as Mem mentioned. I think I remember a disclaimer on one of the laser mice that if it's hooked up through PS/2 that the specs don't apply. With any bus comparison, bandwidth "and" latency should be taken into account.

 

[archcommus]

Good point, but you also must consider the fact that the manual for the MX510 specifically said to use the PS/2 for desktop systems, not either. Why would Logitech print that if they KNOW USB will offer the user better performance?

I'm not arguing with anyone here, just saying that I won't switch until I see a need, which I may or may not, we'll see what my gaming produces.

 

[archcommus]

Looks like USB wins!

Straight from Logitech:

Response (Paka Sampson) 12/28/2004 08:52 PM
Thank you for your recent inquiry about your Logitech MX510 Performance Optical Mouse.

I understand you would like to know which port is best to connect the MX510.

It is recommended that you connect to the USB port, simply because it offers better performance and faster response. However, it does not really matter whether you use the USB or PS/2 port. Its all a matter of convenience.

 

[beverage]

Originally posted by: wchou
There is nothing wrong with PS/2, personally USB is for convenient and is rarely used by most people. Stores like Best Buy sells ps/2 exclusively. usb has to be specially ordered thought.

you're telling me i can't go into bestbuy and buy a mouse that plugs into a USB port?

 

[archcommus]

Yeah that doesn't sound right.

So Logitech basically says that it doesn't matter too much, but USB is indeed faster, and they did say it's recommended.