function for greatest object in list less than or equal to a value

[Richard Gaskin]

Bob Sneidar wrote:

 > On Oct 12, 2015, at 10:41 , Richard Gaskin wrote:
 >> The choice of tying the ticks to retrace was perhaps a necessity
 >> in early Mac OS systems, relying as they did on preemptive
 >> multitasking. But that reliance also made it an inexact quantity:
 >> by default the vertical retrace would happen 60 times a second,
 >> but it was possible to have some processes run long enough to
 >> stall it a bit now and then.
 >
 > That is interesting. I was always under the impression that a tick
 > was always 1/60 of a second. It never occurred to me that this was
 > the standard vertical refresh of the monitors in use at the time.
 >
 > So are you sating that if I had a monitor that refreshed at say
 > 120/sec, that there would then be (roughly) 120 ticks in a second?

But there weren't.  Remember, this is ancient history we're talking 
about, when the only Macs you could buy had a 512x342 monochrome screen 
built into the machine.


 > Also, since processor load can influence real time statistics, but
 > cannot influence the vertical refresh rate, wouldn't ticks then be
 > the more accurate unit of measure?

That's a question better left for systems developers.  Here I'm relying 
only on what I've read, but it seems intuitive enough given that the 
clock on most mobos has its own chip and even its own battery, and that 
refresh rates today vary broadly by GPU type, shared load between GPU 
and on-board, bus variance, etc.

--
  Richard Gaskin
  Fourth World Systems
  Software Design and Development for the Desktop, Mobile, and the Web
  ____________________________________________________________________
  Ambassador at FourthWorld.com                http://www.FourthWorld.com