9/13    From http://dailynews.yahoo.com/h/nm/20000913/tc/apple_test_dc_1.html
        "OS X also offers a technical feature known as ``pre-emptive
        multi-tasking'' which allows the computer user to do more than one
        task at a time without crashing the machine.".  So the previous Mac OS
        (Mac OS 7?) was not pre-emptive?  --- yuen
        \_ no it was originally cooperative multitasking. A scheduled task
           ran until it yeilded. Several RTOS use cooperative multitasking
           as well, notable Cisco IOS.
           \_ So that means Mac OS is even more lame than Windoze in this
              respect?  Ohmygad.
                  \_ Than Lose{NT,2K} yes. Some will argue that pre-emptive
                     leads to worse performance for certain types of workloads,
                     but for non-RT systems, I disagree. As an aside, the kernel
                     in MacOS 8.5 - 9 has the ability (exteremly limited) to
                     preempt/interrupt executing tasks. This is implemented
                     using a mini-kernel (not a full featured micro-kernel like
                     mach).
                     Windows 9{5,8} (they are still basically DOS (the original
                     Denial of Service)) doesn't have this ability, despite what
                     CNTRL-ALT-DEL might lead you to believe.
                     but for non-RT systems, I disagree.

              \_ yes.  -tom
                  \_ Some will argue that pre-emptive leads to worse
                     performance for certain types of workloads (RT notably),
                     but the trade-off is complete service outage due to
                     [ Talking out of my ass here ]
                     individual process failures.

                     taks you do do essential work. But this won't really
                     [ Talking out of my ass here  - ali/tom feel free to
                       correct me ]

                     I suppose that you could write important stuff in the
                     interrupt handlers, so that regardless of the executing
                     task you can do essential work. But this won't really
                     cut it if your interrupt rate is high and your process
                     time in the handler is long.

                     The other option might be to do the important stuff in
                \_ yes.  -tom
                     hardware (asic/fpga) and just run your ui via the OS.
                     This is what most network vendors (Juniper, Cisco) do.

                     [ Done talking out of my ass ]

                     As an aside, the kernel in MacOS 8.5 - 9 has the ability
                     (exteremly limited) to preempt/interrupt executing tasks.
                     This is implemented using a mini-kernel (not a full
                     featured micro-kernel like mach).  Windows 9{5,8} (they
                     are still basically DOS (the original Denial of Service
                     attack)) don't have this ability, despite what CNTRL-ALT-DEL
                     might lead you to believe.