Ipac Usb Vs, Ps/2

[patrickl]

You do realize that you just bumped a 5 year old post  ?

Much has changed since those days.  Well, except that the doom and gloom spreaders predicting the imminent demise of the PS/2 port are now shown to have been incorrect, as I predicted they would be so long ago. 

I don't know what underdeveloped area of the world you live in, but walk into a computerstore and try to buy a computer with a PS/2 connection and based on your results, I'll tell you.

In fact in the developed world, 5 years ago ps/2 ports were a rarity already.

[RandyT]

I don't know what underdeveloped area of the world you live in, but walk into a computerstore and try to buy a computer with a PS/2 connection and based on your results, I'll tell you.

In fact in the developed world, 5 years ago ps/2 ports were a rarity already.

Computerstore......  Here in the third world country that is the U. S. of A, it's computer stores which are a rarity.

Give it up already.  Or do I have to post photos upon photos of Core2 Quad and Phenom systems still sporting the ports just to make you happy?  (please say no...this was absurd then, and it's more absurd now)

[patrickl]

So 1 in a 100 computers still has it and then only the big budget machines. Wow.

I guess you would claim that floppy drives are here to stay too then ...

[RandyT]

So 1 in a 100 computers still has it and then only the big budget machines. Wow.

1 in 100...  not even close.  You shouldn't assume you know the US market, being so far away and all.

I guess you would claim that floppy drives are here to stay too then ...

 

[protokatie]

One thing I have noticed with all of the new PC's I have seen (desktop, not laptop) is that they have the PS/2 connectors. The 300 dollar shitbomb I bought (brand new) a few months ago has them. I am GLAD that they did, as it frees up the more expensive USB ports for things that need the bandwidth. (The 300 dollar machine is my new fileserver and I use external USB drives, so port wastage is a concern to me).
They will go the way of the floppy once there is less demand for them than the cost difference of USB vs PS/2. I wish I can't remember fully, and maybe someone will enlighten me again, but the PS/2 system uses an already available bus, so the connectors are a very cheap add-on... Anyone with info on this?

[SunnyDU]

I can't help myself.  It's been 5 years.  Let's see where we stand.   

On the one hand, you'd be hard pressed to find a PC with a PS/2 port now.

On the other hand, why would anyone buy a PC to run an arcade cab?  People will generally have a stack of old PCs stashed in the garage that have PS/2 ports and will run most MAME ROMs perfectly fine.

[DeLuSioNal29]

Keep this in mind as well in the argument.

http://www.ultimarc.com/ipacusb.html

[RandyT]

This thread is a blast from the past 

It's interesting that the 2-5 year prediction is now 10 years old, and the PS/2 port is still present on many new machines.  It now takes the form of a "dual" function (mouse OR keyboard) PS/2 port, but apparently splitter cables are available to attach both device types simultaneously.

Not gone yet ...maybe in another 5 years

[Skinnysloth]

The PS/2 port is definitely not extinct or rare.  Of the 4 desktop computers in my home, all of them have PS/2 ports.  Although 3 of them are about 5 years old, the one I put together 6 months ago has the "dual" function PS/2 port.

[patrickl]

So the anecdotal "evidence" shows that there are no PS/2 ports on new computers. Perhaps a "dual function" port where you have to find a cable and be "lucky" that it's hidden inside.

That was pretty much as predicted yes.

[RandyT]

That was pretty much as predicted yes.

Except that there are PS/2 ports on many new computers...and 10 years later at that.  The interesting thing is that the industry is somewhat successfully phasing out the entire desktop PC for the average "check your email, surf the web and balance the checkbook" types, so much of this is becoming moot fairly quickly.

But there will always be cheap, older and very capable computers with PS/2 ports for the kinds of things we need them for around here.

[DeLuSioNal29]

I bought a top of the line one last year and it still had a PS/2 port on it.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131877&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-AMD+Motherboards-_-N82E16813131877&gclid=CLnG1ueX6cACFYMF7Aod1DoA-A

D

[patrickl]

No, not "many". Very few in fact and even then pretty much only with "combo" ports.

So sure, old junkers will be available for some time, but that wasn't what was "predicted".

[SunnyDU]

I'm just going to throw this out there and say that the predictions from both sides were off the mark a bit.

Arguing that PS/2 is not obsolete by providing links to support you claim and saying that you can still get one is weak.  If that's your argument that must mean VHS is also not obsolete.  (http://www.amazon.com/Toshiba-SD-V296-Tunerless-Combo-Player/dp/B001DZFYPW/ref=sr_1_1?ie=UTF8&qid=1410995510&sr=8-1&keywords=dvd%2F+vhs+player)

PS/2 is definitely obsolete (for the regular consumer market), but there is clearly an extremely strong specialized market for it that isn't going anywhere anytime soon.  So any argument saying that you should buy a USB encoder because PS/2 is obsolete is equally as weak. 

Now that that's settled I would really like to know if there are still differing opinions and/or facts on the performance of each given what we know now?  Let's please assume that the system this is running on is a dedicated arcade cabinet with no other USB relevant devices connected.

[RandyT]

Arguing that PS/2 is not obsolete by providing links to support you claim and saying that you can still get one is weak.  If that's your argument that must mean VHS is also not obsolete.  (http://www.amazon.com/Toshiba-SD-V296-Tunerless-Combo-Player/dp/B001DZFYPW/ref=sr_1_1?ie=UTF8&qid=1410995510&sr=8-1&keywords=dvd%2F+vhs+player)

While the comparison isn't exactly apt, I'll play along.  But first, let's get semantic:

ob·so·lete

adjective
1.
no longer produced or used; out of date.

PS/2 ports and devices are in fact still produced and used, so yes, the fact that you can also purchase newly produced VHS players/recorders does refute the claim of obsolescence in both cases.  Sure, you can purchase a DVD player which does not have a VHS machine in the same box, but that doesn't negate their existence, nor the demand for them.  Just as with PS/2, VHS has been around for a very long time.  Consumers have amassed huge collections of media which they still want access to.  It could be argued that those same consumers could transfer those recordings to more modern media, but doing so is time consuming, and often times not particularly simple to do.  It also requires an investment in the new media, and the hardware to do it well.

The reason both of these still exist is that they are dead simple to use, and because of their age and mass adoption, the technology is inexpensive and nearly "bullet-proof".  In their purest forms, it takes no special knowledge or support  to operate them.  They just work.  In the case of PS/2, this meant that consumers could plug in a keyboard or mouse, without worrying about special drivers for extensions to the standard operation.  USB keyboards have a "Boot Protocol" which is similar, and operation is virtually guaranteed across any device or operating system.  However, with it comes some severe limitations when used for anything but a standard keyboard application.  USB is, however, more open ended, and can circumvent those limitations with modified report structures.  The caveat is that the operating system must allow for and properly handle those modified reports for them to work as intended.  Otherwise, special drivers are required.  PS/2 does not have the limitations of a "Boot Protocol" USB keyboard device, so even the most basic OS support makes them "plug and play".

That's not to say that some extended features of PS/2 keyboards and port hardware are always supported across all devices.  On rare occasions, a PC manufacturer will deviate to support a feature on their own non-standard keyboards, or simplify it to the point that it  can cause some compatibility issues where two-way communication is involved, but you can always count on the basic operation to be solid.

[SunnyDU]

You may be missing my greater point.  I could care less whether PS/2 ports are obsolete or not regardless of how Webster defines the word.  My interpretation of the prediction was that the mass market would not be using the PS/2 port anymore and that this prediction was very relevant to main topic/question originally posed 10 years ago.

My statement was more calling attention to the irrelevance of the ubiquity of the PS/2 port in relation to the topic/question.

I'll side bar for a second though and disagree that simplicity is the reason it's still around.  The reason is lives and will continue to live in specialized markets is entrenchment.  The market doesn't care about simple, the market cares about making money.  As long as there's a market for it and the cost continues to be justified, PS/2s will still be available.

I'll finish by repeating my question. Is there are still differing opinions and/or facts on the performance of each given today's technology and what should now be provable historical evidence of performance metrics of each technology (PS/2 versus USB).  Please continue to assume that the system this is running on is a dedicated arcade cabinet with no other USB relevant devices connected.

[AndyWarne]

We will be dropping PS/2 support on the I-PAC range in a couple of months. The only reason we have kept it going is owing to a false belief that PS/2 is better than USB. Its not. PS/2 is obsolete, end of story and from a purely technical point of view we should have dropped PS/2 support years ago.

The DOS argument doesnt stand up because if you are using DOS on a modern motherboard the PS/2 issue is the last of your worries, DOS is terrible on modern hardware both in terms of I/O and video performance.

Motherboard manufacturers have propped up PS/2 support by tacking it on as an afterthought onto the ACPI power control subsystem and its implementation is poor and has been for years. Windows support of it is also poor. The PS/2 interface has not been maintained as any kind of standard for years since IBM disowned it and incompatibilities are rife.

I was involved a couple of years ago with a project for a bank data entry center which used PS/2 keyboards. They replaced all the PCs with Dells which were the last ones to have PS/2. The keyboard performance was so bad that they had to junk them all and replace them with new USB ones.

USB out-performs PS/2 by a huge margin and nobody should be using PS/2 for gaming on modern OSes or hardware.

[RandyT]

PS/2 is a true serial interface, with regard to individual keypress events, while USB keyboard devices are not.  USB input events are packetized, and not necessarily acted upon by the system in any specific order if received within the same packet.  The only reason this doesn't matter with keyboards is the fact that it is extremely unlikely that a person typing at a simple keyboard will be typing fast enough to cause multiple input events to occur within the same packet.  This is not the case where keyboard technology is used as a gaming controller, and multiple events can be occurring across several users, nearly simultaneously.  When this occurs in the case of fighting games, when one player executes a move a tiny fraction of a second before the other, there is no guarantee that the player who actually executed the move first, will actually be given priority.  In devices where multiple keyboard devices are reported by the same physical device, this can become worse if that player's input happens to be relegated to a different keyboard device than the one being reported next.  This is, of course, dependent upon the implementation, but users have no knowledge of these kinds of things to know exactly what workarounds are in use to get past simultaneous keypress limitations.  It can be done well, or not well at all.  This is not the case with PS/2.

For bank data entry and Point of sale, PS/2 was the norm for just these reasons.  The devices used were often piggy-backed onto the keyboard data stream, which meant that to the system it was attached to, it appeared as though the user had actually typed the data, albeit very quickly, and the data order would always be correct. 

For arcade gaming, the PS/2 protocol works perfectly.  It is way more than fast enough for the 60hz polling cycles of arcade games, and it is extremely reliable.  In fact so reliable, in cases where users have issues with using USB on some of the dual-compatible devices, the first suggestion is to use the PS/2 capability if present on their system.  When that advice is followed, their issues seem to go away.  That alone tends to speak volumes in support of using it, if one can.

As for it being an "afterthought", I find it odd that one would think a special two color connector to indicate either mouse or keyboard compatibility, and appropriate connection to support both without interference, was an afterthought.  It seems pretty well thought out and implemented to me. 

BTW, Dells are the oddball when is comes to keyboard issues.  Every time I have heard of an issue with a keyboard, the name Dell always seems to pop up.  Not with all of their systems, mind you, but they dropped the ball with some of them, even to the point where they were very picky about even regular keyboards working, when it did not carry their brand name.

[SunnyDU]

When this occurs in the case of fighting games, when one player executes a move a tiny fraction of a second before the other, there is no guarantee that the player who actually executed the move first, will actually be given priority.

Wouldn't that depend on how the encoder handles the buffering? Couldn't the encoder guarantee order prior to sending by not "packetizing"?

Either way, seems like both sides of the statement could be provable with some asynchronous testing and metrics for out of order hits or something similar.

[AndyWarne]

USB wins in fighting games owing to the need for detecting complex moves involving simultaneously pressed keys whereas PS/2 is a slower serial interface.

In spite of the PS/2 interface being simple at the hardware level, the data still has to get through all this lot: http://msdn.microsoft.com/en-us/library/windows/hardware/jj128267(v=vs.85).aspx

At the end of the day the game is the limiting factor in determining whether very closely-spaced keypresses happened at the same time or not, and would have trouble with either interface. USB is certainly not an issue in this respect as the packet rate is faster than the poll rate of the game. The original hardware would poll the input bus receivers at a certain rate and read all pressed keys at the same time. This is closer to USB in which all pressed keys are sent in one go.

I am not going to debate this any more because this debate has gone on longer than it should already. Much like the PS/2 interface itself

[RandyT]

USB wins in fighting games owing to the need for detecting complex moves involving simultaneously pressed keys whereas PS/2 is a slower serial interface.

"Slow" is an extremely relative term in the data realm.  PS/2 communicates at rates of up to 16khz, which is up to 1600 keypresses or 800 releases per second.  Considering that it's a dedicated port specifically for that one function,  it has more than enough speed for gaming controllers.  As indicated, on original hardware, any events which occur prior to the next screen blanking will be considered as having occurred simultaneously.  At that point, the original games internal code would decide priority.  However, input data is buffered by the OS, and given the time constraints, the emulation code will at some point need to stop reading data from the buffer so it can perform other tasks.  What is being discussed is the order in which these events are placed into the buffer to be read by the application.  If the system cannot guarantee the order in which data from the USB packets is placed into the buffers (and MS states it can't) then you have a possible scenario where an event can be delayed by a frame, even though it physically occurred prior to an event which was not delayed.  The same thing can happen with the "complex moves" described above, but this particular scenario could occur with either input device type.

In spite of the PS/2 interface being simple at the hardware level, the data still has to get through all this lot: http://msdn.microsoft.com/en-us/library/windows/hardware/jj128267(v=vs.85).aspx

Which is still quite a bit less than an HID device.

...  gone on longer than it should already. Much like the PS/2 interface itself

I guess we will agree to disagree on that point.

[DeLuSioNal29]

To be honest, the only reason that I chose PS/2 for my encoder was that it freed up a USB port for other purposes.  I figured, hey, if there's a port there I might as well use it.  It's worked well for me. 

Moving forward though, the MB manufacturers now have tons of extra USB ports, so for me it's no longer an issue.   

DeLuSioNaL29