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Encoder Comparison Pages Back Online
Tiger-Heli:
Just wanted to let everyone know my encoder pages are back online at: http://www.mameworld.net/tigerheli/ They even got a home page to tie everything together. I also included my comments on the Retroblast review of the KeyWiz.
(I know I need to update the pages to cover the I-PAC/VE, MiniPac, KeyWiz MAX 1.5, and maybe the new Two-Bit Score encoder on E-bay, and show the MK64 as discontinued, I'll get to it . . . )
Enjoy!!!
patrickl:
Heh, I see you still believe the performance of PS/2 is better ::)
Really, someone should clock that sometime to get this out of the way. I'd put my money on USB (since the bandwith is vastly superior and a few interrrupts are not gonna kill that lead) On the other hand, who cares. With games running at 60Hz (max) the computer has ages to wait on your keypresses. Still, it would be nice to know.
Nice overview though. You sure take a lot of time to research all these things. very impressive work.
Bgnome:
i would be interested in seeing an updated review.
i just got the Two-bit encoder and soldered a ps/2 splitter for it last night. i am now waiting on my joysticks/buttons so i can test it out on a temp cp..
if you need more info on it, i posted a fairly informative email about it in another thread and am willing to post whatever other info i have, (pictures, key map, etc.).
RandyT:
--- Quote from: patrickl on August 12, 2004, 02:56:46 pm ---Heh, I see you still believe the performance of PS/2 is better ::)
--- End quote ---
And I see you still haven't done any research to support your rolly eyed posts. ;)
--- Quote ---Really, someone should clock that sometime to get this out of the way. I'd put my money on USB (since the bandwith is vastly superior and a few interrrupts are not gonna kill that lead) On the other hand, who cares. With games running at 60Hz (max) the computer has ages to wait on your keypresses. Still, it would be nice to know.
--- End quote ---
Yes, someone should. But there is more at play than raw bandwidth when comparing these things. 1.5mbs is a theoretical maximum of a "low-speed USB device". How close any device, especially a keyboard device, comes to this speed depends greatly on the capabilities of the microprocessor used in the device, the efficiency of the code inside and the software support of the host system. Try using USB with the rudimentary support included in the BIOS of most motherboards if you don't believe this to be true. It might work, but you wouldn't want to use it for anything. On the other hand, the BIOS support for PS/2 works very well.
This reminds me of the Commodore 64 days and the push to attach high-speed modems to it. In theory, you can use every available processor cycle to pump a data byte out of the port at 9600bps. The problem was (and maybe still is, I haven't looked at the 64 scene for while;)) that even though technically the 64 was speaking at 9600 baud, it could only assemble the data prior to transmission at a rate similar to that of a 2400 or 4800 baud modem.
In other words, bandwidth does not necessarily equal throughput. And this is just one of a number of possible variables that can affect performance.
You might also wish to ask the question why, when given the choice of using either interface on an encoder that supports both, PS/2 is usually the one used. There must be a reason, no?
--- Quote ---Nice overview though. You sure take a lot of time to research all these things. very impressive work.
--- End quote ---
Absolutely. the dedication to those pages impresses me every time I look at them. Nice job TH!
RandyT
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spelling....
RandyT:
--- Quote from: patrickl on August 13, 2004, 05:57:31 am ---Ha, ha, Randy. You always know to find some out of the way example ("a very crappy USB device might be slower than a non crappy PS/2 device" or "many many years ago there was a computer whith a really slow CPU that was unable to completely use up all the bandwidth") to "prove" your point. Again I wonder why you claim I didn't research the issue. Of course if you attach a crappy USB encoder it will not work, but the i-PAC is a fine encoder and it does work. What 's the point of such statements?
--- End quote ---
The point is, it was a real world parallel of the difference between the "marketing hype" and what is actually the case in a lot of instances with USB devices. I'm sorry it was lost on you, I'll try harder next time.
And for the record, you just attempted to turn this into "yet another KeyWiz VS IPAC" debate, which I am not going to get into again. The statements I am responding to regard your general "USB is always better" rhetoric, nothing more.
--- Quote ---If you want some point actually relating to the discussion at hand then think about this; 1.5Mbps is the theoretical maximum bandwidth for USB. For PS/2 it's something like 10kbps. I'm pretty sure that factor 150 will matter much more in delays than any potential interrupt conflicts.
--- End quote ---
And this is what shows your lack of research or real understanding of the topic at hand. Your statement is along the same lines as this one:
"A car travels at 400 miles per hour, therefore a car is faster than a plane."
While this isn't necessarily a false statement, it is pretty far from being accurate. Yes, a car has traveled at 400 miles per hour. Does your car? Does mine? Does any production model? Can it turn a corner? Can it maintain that speed long enough to be useful? Which plane?
Your statements use theoretical maximums as though they were the norm, and therefore are misleading and not entirely factual.
--- Quote ---Actually PS/2 is so slow that it cannot even be used in some applications (for instance high res tablets). PS/2 doesn't offer enough bandwidth for the necessary information stream.
--- End quote ---
And you wouldn't want to use it for transferring data from an external Hard-drive either, but what bearing does that have on the point? Until well after USB was introduced, artists tablets produced by WACOM and others used normal RS-232 serial. Not much of a speed demand there I guess, as these functioned easily at 9600 baud (slower than the PS/2 bus.)
A byte of data sent over the PS/2 keyboard port is framed at 11-bits. The max quoted frequency of the clock is around 16.5khz, or 16500 bits per second. Drop that back some to 15000 bits per second for compatibility purposes, divide it by 11 and you have roughly 1363 bytes of data per second. Normal keys on a keyboard generate 3 bytes of data, 1 at depress and 2 at release. So even if it were possible to press and release 454 buttons within the time frame of 1 second, the PS/2 bus should still be able to handle the traffic.
--- Quote ---I'm not so sure 4 players pounding many buttons and wielding 4 joysticks wouldn't give much more problems on a PS/2 encoder than the possibility of say a printer needing an occasional USB interrupt delaying your USB encoder. I'm pretty sure bandwidth issues give a much bigger delay problem than any possible USB interrupts blocking the USB encoder might.
--- End quote ---
If you aren't sure, why make statements like these? I can tell you that I am sure that there would be no issues with PS/2 in this instance, at least not caused by a limitation in the interface.
If you would like to conduct a test, wire your encoder up so that a single button activates all inputs and use a program like Ghostkey to monitor the results while clicking the button a few times in rapid succession. Hold the last press and record what you see on the screen.
Do this with both USB and PS/2 and then tell me which one you think will have the greatest possibility of a problem in the scenario you presented. I await your results.
--- Quote ---For more normal use I wonder if any performance benefit (be it for PS/2 or USB) will actually matter? Will you even notice a couple of ms delay?
--- End quote ---
Some people notice the absence of certain frequencies in their music, even though most can't hear them to start with. Some are annoyed by 60hz flicker in fluorescent lighting although millions don't even notice. You tell me. But one thing is certain, if it doesn't feel right to you, it probably isn't. Before I designed the KeyWiz, I was using a PS/2 keyboard hack. I used to think it worked pretty well, until I made the switch. Turns out that the keyboard had an inferior processor and I didn't know the difference until I actually had a frame of reference.
So yes, a few ms of delay can be noticed if present.
--- Quote ---I guess it's habit and it's cheaper (initially). For me it was mostly caused by people spreading misinformation. When I bought my i-PAC the 6 button myth was still alive. In the meantime Andy Warner explained the 6 button restriction is nonsense and that speed wise there is no difference. That is much more important to me than people quoting reference manuals. Andy really does know how it works since he build the thing.
--- End quote ---
What goes on between you and your mentor is not for me to comment on. However, "habit" as a reason to use PS/2 over USB is just plain silly :) There actually are valid reasons and that isn't one of them.
--- Quote ---...I don't want to rewire my controller when I switch to a new computer and so I don't want to depend on PS/2 alone. In fact my current PC has no PS/2 port.
--- End quote ---
I'm sorry your salesman was able to convince you that less options was actually a "feature" on the system you bought. Better luck next time. Meanwhile, 90%+ of current systems still have the full complement of ports.
--- Quote ---- It's much easier to connect control panels to the PC. You put the hole stuff in the CP box and one wire comes out. For instance, rotating panels aren't gonna happen without USB.
--- End quote ---
More misinformation. Ever hear of switching connections at the input side of the encoder rather than the output side?
[rhetoric about "everyone is changing to USB" snipped...they said it would have happened already, they tried, it still hasn't and isn't going to soon. We did this one before}
--- Quote ---Are all gamers who use USB joysticks, steering wheels, trackballs, game pads and such suffering from poor gameplay? In fact, how many people insisting on PS/2 for their keyboard encoders have a USB trackball or USB spinner in their CP?
--- End quote ---
Well, the true arcade trackballs from Betson use PS/2, as well as the one on my cabinet. I engineered replacement encoder wheels for the Betsons with 4x the resolution and it doesn't skip a beat. USB gamepads, steering wheels and joysticks don't pretend to be keyboards, so not an apt comparison. But I'm sure they work fine. Better? Not necessarily.
--- Quote ---The only reason to go for PS/2 is if you use an older computer or older OS and USB doesn't work really well in it yet (or maybe even not at all). In all other situations USB just makes much more sense when you think about it (especially in the long run). I guess it just hasn't gotten through to people yet.
--- End quote ---
I guess it's a good thing we have you here to get it through our thick skulls. Sheesh! :)
--- Quote ---It's not that big of a deal so why bother thinking about it? Well, at first I didn't think things through either so I went for PS/2, but in the end I got bitten and after I researched things I now understand that USB is the better option. I'm really happy my encoder was ready for USB.
--- End quote ---
Err.. how were you "bitten" again? Anyway, you have your opinion, I have mine and everyone else has theirs. I'm glad you are as happy with USB as the thousands of others are with PS/2. Isn't that what it's really all about in the end?
RandyT
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spelling.......
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