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Ipac Usb Vs, Ps/2
Tiger-Heli:
--- Quote from: patrickl on June 15, 2004, 04:35:39 am ---OK, let me recap this. On the one hand we have a clear explanation (from someone who obviously knows his stuff) about how it does work.
--- End quote ---
I've seen at least three explanations from people who seemingly obviously know their stuff and they tend to conflict in their conclusions. I'm sure you aren't talking about me, but are you referring to Andy Warne, RandyT, or Krick (or maybe RonM)? (Rhetorical Question).
--- Quote ---On the other hand we have some unsubstantiated (and vague) claims that in some theoretical case there might be problems.
--- End quote ---
They may be vague, but hardly unsubstantiated. Take a look through the archives on BYOAC, and you will find five or six examples of cases where the I-PAC did not work in USB mode and did work in PS/2 mode. (Due to performance issues). I can't remember any cases of it not working is PS/2 mode but being fine in USB mode (but there might have been a couple, excluding mis-set jumpers and such).
Generally, this probably doesn't reflect the real picture b/c:
1) In an arcade machine, you will not have a huge amount of usb devices - Most of us aren't running USB HD's or Digital Cameras or Floppy Drives, or Printers in our arcade cabs.
2) Since all previous versions of the I-PAC (not the new VE) were capable of running in PS/2 or USB, the I-PAC provided an active keyboard pass-thru, and most people rarely used a keyboard in an arcade machine, the inconvenience of switching to PS/2 from USB is minimal for most arcade cab builders. In other words, I suspect there are quite a few people who might have planned to use USB, but if it didn't work, PS/2 was just as good.
--- Quote ---If the only points are:
- if one hooks up a completely crappy USB device on the same bus as the I-PAC it might not work properly
- if you use some flakey keyboard drivers (other than the standard ones that obviously DO work) you might have a problem
then to me that seems like someone is grasping at straws to find some argument.
--- End quote ---
Are you sure those are the only points?
I stated that I saw a performance lag in MAME with a single USB PC trackball. The ball was plugged into a USB hub (alone) and I also have a USB mouse and USB printer in the system. MAME would occasionally hesitate, and it didn't do this with my PS/2 mouse, but it wasn't enough to make me want to go back to PS/2. Oddly, I can't remember if I saw the same problem with the USB mouse without the trackball hooked up, but maybe not.
BTW, the genuine problems that I've heard were not specifically flakey keyboard drivers, but flakey BIOS support for USB keyboards, and flakey BIOS support for USB 2.0 or USB 1.1. You can't really use "standard ones that do work" for BIOS support, unless you flash your mobo and hope it still works.
RandyT:
--- Quote from: patrickl on June 15, 2004, 04:35:39 am ---
BTW, as an indication as to how fast things can change from PS/2 to USB; remember how fast the old DIN keyboard connectors were replaced by PS/2? That took 5 years or something?
--- End quote ---
Let's think about that one for a moment. It took 5 years (or more) for the AT connector to be phased out.
The reason that one was implemented so quickly was due to the fact that a simple passive adapter is all that is required to make the move. To the end user, it was just a physical change because PS/2 is backward compatible. So, not surprisingly, you are comparing apples to oranges.
Take a look at the Serial and Parallel ports. A lot of people don't seem to understand that there are a huge amount of peripherals out there that use these, and a good number of them are worth more than the PC's they are attached to. Where are all these expensive add-ons? Business and Research. Who buys the most computers? Not little Billy who only checks his email and downloads PrON, but Business and Research.
Computer companies are not stupid and will not shoot themselves in the foot. You won't see widespread "Legacy-Free" PC's until a large majority of these expensive devices are obsolete themselves. And then you will see add-on I/O cards with PS/2, Serial and Parallel ports on them, but that won't be for a good long time yet.
Was that a clear enough explanation? :)
RandyT
patrickl:
--- Quote from: Tiger-Heli on June 15, 2004, 07:30:48 am ---
--- Quote from: patrickl on June 15, 2004, 04:35:39 am ---If the only points are:
- if one hooks up a completely crappy USB device on the same bus as the I-PAC it might not work properly
- if you use some flakey keyboard drivers (other than the standard ones that obviously DO work) you might have a problem
then to me that seems like someone is grasping at straws to find some argument.
--- End quote ---
Are you sure those are the only points?
--- End quote ---
Well yeah, 1 is the lag and 2 is the claim that you can't press more than 6 keys at the same time.
Point 2 seems easy to prove and I claim it's proven to be false. At least I have no problem with it. Certainly not that my PC will reset if I press (more than) 6 keys at the same time as I have read in some threads.
Point 1 is harder to prove/disprove. But it just doesn't make sense. I can't see how another HID device could incur so many interrupts or be so slow that it would make other USB devices work poorly. The offending device would then be probably too poorly designed to work properly on it's own. I'd rather replace the faulty device than blame the I-PAC. I would also assume that you could just use another USB channel and not have any conflicts at all.
:edit:
There are so many games devices connected via USB. Are you saying these don't work either? In fact most computers will probably have an USB mouse. Have you ever experienced any weird laggy behavior in the cursor movement?
Tiger-Heli:
--- Quote from: RandyT on June 15, 2004, 07:59:08 am ---Was that a clear enough explanation? :)
--- End quote ---
Well, just to play both sides of this issue -
I recently read a headline on www.anandtech.com that said new Intel chipset boards have an AGP slot, even though Intel said they officially don't want to support it on that chipset and wanted to go to PCI Express.
OTOH, while there seem to be many esoteric serial and parallel interface devices, the PS/2 ports have typically only been used for keyboards, mice, trackballs, (maybe) graphics tablets, and recently keyboard encoders. Except for the last two items, these are low-cost, low-performance devices and for the casual user, if not replaced, can be converted to USB using the $6.99 QVS adapter that I used to move my keyboard to USB.
The biggest argument to continue support for PS/2 devices would be DOS and Windows NT support, as Linux supports USB and hardly anyone uses Windows 3.1 or early 95 anymore. But many mobo manufacturers no longer provide DOS drivers for on-board components such as Ethernet controllers and sound cards, etc., so this is probably a minor concern for them.
Bottom line is computer manufacters will support PS/2 as long as there is demand for it and it is cost-effective for them to do so.
If they feel people might spend $3 more for a competitor's board b/c it offers PS/2 and their non-PS/2 solution would require many users to spend $10 on a PS/2 Keyboard/mouse combo, they will keep the PS/2 ports. If OTOH, they feel that they could offer six rear USB ports for less than 4 USB ports and 2 PS/2 ports and more people will buy this, they will drop PS/2 in a heartbeat.
At least that's my opinion, not that I work for a mobo design team.
patrickl:
--- Quote from: RandyT on June 15, 2004, 07:59:08 am ---Was that a clear enough explanation? :)
--- End quote ---
Dear lord you're such a condescending git ::)
Obsolete PC standards have been seen to phase out in short times over and over again. You can give all the rational you will, but it happens time and time again. Indeed RS232 and Parallel ports are still here, but they still serve a purpose. There is no reason for PS/2 connectors to remain. It's not like there is no replacement available. They are only used for keyboards and maybe a mouse. If you buy a new PC it comes with a mouse and keyboard anyway. Besides, all new mice and keyboards you buy can be used on USB and PS/2 (it just takes a similar simple connector which you claim killed the DIN keyboard plugs). So they will still work on a USB only PC and therefore it doesn't matter one bit if there is no PS/2 connector.
The only problem I had (I just purchased a "non PS/2" PC) was that my I-PAC didn't work, but that's just because I took the vague claims about USB not working too serious and thus I did not buy the USB cable straight away. That was my mistake and one I won't make again.
Fact is, major PC manufacturers have skipped PS/2 connectors already (at least I have seen this in the Netherlands to be the case).
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