houghton@iuvax.cs.indiana.edu (Ric Houghton) (03/27/91)
We are thinking of purchasing a color NeXT station for research
purposes (040 cube, with 40 megs of ram, and a 600 meg harddisk). The
only problem is that the required task is timing sensitive. That is,
we need to be able to reliably present a visual stimuli at some time
x, after another stimuli, auditory (or maybe another visual stimuli)
has been started. (Where x is measured in milleseconds.)
Does anyone have a feel for how accurate or reliably we might be
able to do this task? +/- 1 millesecond is acceptable, but more than
that, and we have to start thinking about PC's or Macs. (YUCK!)
Intuitively, it seems almost impossible to assure the experimenter
that the task will be carried out reliably, but I've not worked with
MACH, so I have no clue on this one.
Thanks for what ever input,
I'll summarize, of course....
Ric Houghton
houghton@cs.indiana.edu
btw, Any chance there exists a real-time unix for the NeXT?
Probably not?.....<DWN2@psuvm.psu.edu> (03/28/91)
In article <1991Mar27.082322.27952@news.cs.indiana.edu>, houghton@iuvax.cs.indiana.edu (Ric Houghton) says: [almost entire note deleted] > btw, Any chance there exists a real-time unix for the NeXT? > Probably not?..... I have read that CMU is doing real time MACH (check comp.os.mach) but don't know if this can be moved to the Next. You might talk to someone at CMU about it. They seem very helpful whenever I contact them. Dave
dennisg@kgw2.bwi.WEC.COM (Dennis Glatting) (03/30/91)
with the limitation of +/- 1ms i would say: no.
what i did was develop a devide that performed the time critical stuff
then interacted with the NeXT through a serial interface. in this fashion
my real-time constraints were met and the NeXT could do the heavy processing.
--
..!uunet!kgw2!dennisg | Dennis P. Glatting
dennisg@Xetron.COM | X2NeXT developer
| NeXT/C++/Objective-C wienieizumi@mindseye.berkeley.edu (Izumi Ohzawa) (03/30/91)
In article <2122@kgw2.Xetron.COM> dennisg@Xetron.COM writes: > >with the limitation of +/- 1ms i would say: no. > >what i did was develop a devide that performed the time critical stuff >then interacted with the NeXT through a serial interface. in this fashion >my real-time constraints were met and the NeXT could do the heavy processing. I would say no too. NeXTdimension, with right hooks, should be able to do animation with guaranteed timing accuracy down to frame period. I don't know if there will be such hooks in the Appkit timed entry functions. On ohter systems which use 040 for display handling, there's no way you can guarantee that sort of timing. Have your PC or Mac generate visual stimuli at timing resolutions upto the frame rate. Let them also generate trigger pulses on a digital I/O line, feed that to the DSP port along with other events such as button presses through a multiplexer. DSP chip can run a clock which time stamps these incoming events. Your NeXTstep app can then receive these buffered events whenever it can. Parameters for the visual display can be sent down the serial line to the PC or Mac as Dennis suggest. Izumi Ohzawa [ $@Bg_78^=;(J ] USMail: University of California, 360 Minor Hall, Berkeley, CA 94720 Telephone: (415) 642-6440 Fax: (415) 642-3323 Internet: izumi@violet.berkeley.edu NeXTmail: izumi@pinoko.berkeley.edu
cyliax@ecn.purdue.edu (Ingo Cyliax) (03/30/91)
Why not use the DSP for realtime processing ? One can hang all kinds of neat stuff on the 2 DSP serial ports. I guess I don't know what kind of 'visual/auditory stimuli' the original author was talking about, but it seems like the DSP would make an OK experiment controller. -ingo -- /* Ingo Cyliax ECN, Electrical Engineering Bldg. * * cyliax@ecn.purdue.edu Purdue University, W. Lafayette,IN 47907 * * cyliax@pur-ee.UUCP Work: (317) 494-9523 * * cyliax@flaubert.laf.in.US Home: (317) 474-0031 */
songer@orchestra.ecn.purdue.edu (Christopher M Songer) (03/30/91)
Speaking of applications for the DSP -- According to the NeXT literature, the DSP memory is supposed to be upgradable to some number >500K (I can't remember the exact number) Where does one get this memory? Where does it go on the board? What kind of memory is it? Thanks! -Chris