One mouse click, 2 PC's
in [Design]
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From: mpm on 14 Jun 2010 20:52 On Jun 14, 5:45 pm, "Joel Koltner" <zapwireDASHgro...(a)yahoo.com> wrote: > "mpm" <mpmill...(a)aol.com> wrote in message > I don't think you can say that without specifying a polling rate, and > certainly the distributions are different: Interrupt-driven I/O has latencies > that peak at some small value and then a "long tail" that's created when > interrupts are being held off for one reason or another. Polling I/O has > latencies that are very close to a uniform distribution. > > Personally I find polling using the main CPU distasteful once it hits more > than about 10Hz. > > ---Joel I disagree. I don't think you can really characterize either one (interrupt or polled) in too general terms. Much depends on how long the routine (or routines) will be before control is returned to the main program. For example, some software disables further interrupts until the existing interrupt is completed, etc... Some just do a quick flip of a few registers and return control. Others might commence length file operations, etc... Not starting an argument. I mean, I do get the thrust of your statement. It's probably generally safe to say that polling systems are quite uniform, provided no interrupts are being serviced at the time. Whereas by contrast, something that is interrupt driven could be downright asynchronous! To anything.
From: Joel Koltner on 14 Jun 2010 21:10 "mpm" <mpmillard(a)aol.com> wrote in message news:add7e87b-5d51-494d-9389-ecfceab08c43(a)u26g2000yqu.googlegroups.com... > I disagree. I don't think you can really characterize either one > (interrupt or polled) in too general terms. > Much depends on how long the routine (or routines) will be before > control is returned to the main program. That's a good point. I've always been of the mind that interrupt routines should do "relatively little" and return. For microcontroller-based hardware, often that's all that's needed -- but as was also mentioned, for high-falootin' OSes like Windows and Linux it often turns into a two-step approach with deferred procedure calls. You're certainly correct that some programmers who write perfectly functional code spend a *very* long time in interrupt routines with interrupts disabled. I once wrote some bit-banged serial port routines that ran off of a timer interrupt and was a little annoyed to find that I had to drop the bit rate from my initially envisioned 9600bps down to 1200bps because the guy who wrote the USB stack did this... >It's probably generally safe to say that polling systems are quite >uniform, provided no interrupts are being serviced at the time. >Whereas by contrast, something that is interrupt driven could be >downright asynchronous! To anything. Good point. Hopefully you don't have to program too many systems that deviate that far from what I think is the "intended" model of interrupt-driven vs. polled I/O. :-) ---Joel
From: mpm on 14 Jun 2010 21:13 On Jun 14, 5:29 pm, greghan...(a)prograde.com (Greg Hanson) wrote: > On Mon, 14 Jun 2010 12:45:15 -0700 (PDT), whit3rd <whit...(a)gmail.com> > wrote: > > >On a serial port mouse, it'll work; just be sure your mouse can drive > >two > >serial receivers with a big enough signal. A Y-cable might be > >enough, > >not even any reason to open the mouse. > > Thank you to all those who have kindly posted replies on this topic. > > My reason for doing this is to synchronize two sets of stereo signals > (audio) ... one set generated in software in each identical PC > (Celerons). This is because I can find no affordable device that will > record and playback simultaneously FOUR separate WAV or MP3 files. > > If there are, somebody please let me know. > > Since all generated signals are within the audio spectrum, I suspect > interrupt and polling will not be significant factors. > > All things considered though, the above suggestion of wiring a single > SERIAL mouse to both ports seems like the most straightforward option > so far. This is intended to activate the "play" button of the software > audio signal generator. > > Greg Hanson Hey Greg... What about those multi-track recorders that musicians use? I've seen several in the ~$200 -ish price range. They are pretty cheap these days, and most will offer more features than you will probably want or need! I have a Fostek MR-8 Digital Multitracker and I'm reasonably sure it will do what you want. I use it for my keyboards (piano, mostly). The Fostek treats each track as it's own WAV file (might be an MP3, but I think only newer models handle those..?) It's an older model, uses CF memory (yuk!), but you can probably find a used one on eBay for around $100 or so. On mine, you'd have to double up mono tracks 1 & 2, and also 3 & 4 to make stereo tracks. Or use tracks 5/6 and 7/8, which can be confiured as either mono or stereo. Anyway, I don't want to suggest too strongly that something like my old Fostek unit is the ultimate way to go. There are almost certainly better models out there. Try checking out the music stores in your area. Try: www.samash.com or www.guitarcenter.com You may find an even better (and possibly cheaper?) solution to play/ record multi-source stereo tracks (MP3 source audio). Good luck. -mpm
From: Archimedes' Lever on 14 Jun 2010 21:46 On Mon, 14 Jun 2010 18:13:07 -0700 (PDT), mpm <mpmillard(a)aol.com> wrote: >> My reason for doing this is to synchronize two sets of stereo signals >> (audio) ... one set generated in software in each identical PC >> (Celerons). This is because I can find no affordable device that will >> record and playback simultaneously FOUR separate WAV or MP3 files. >> >> If there are, somebody please let me know. Simply drop a second audio card into your first PC. There are set-ups out there with four.
From: Greg Hanson on 14 Jun 2010 22:13
On Mon, 14 Jun 2010 18:46:47 -0700, Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote: > Simply drop a second audio card into your first PC. > OK, but the commercial audio editing software I use (CoolEdit) only generates a stereo signal. If I open a second instance of it, how do I force it to address the second soundcard? There appears to be nothing in the program itself that will enable this. IOW if you change the default device in one instance, it changes it in all. Any suggestions? Another respondent mentioned 4 track recorders. My associate Ken (the OP) said he looked into these and, while they record 4 channels for mixing purposes, only 2 can be output, as a conventional stereo signal. At least for the lower cost models examined. Greg Hanson |