kim@amdahl.amdahl.com (Kim DeVaughn) (12/24/87)
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CIS: 76535,25jbn@glacier.STANFORD.EDU (John B. Nagle) (12/24/87)
Please, could we turn down the flames a bit.
On the systems that don't have multi-tasking, such as the IBM PC and the
Mac, we observe people desperately fighting the operating system to get some
concurrent operations going. Terminate-and-stay-resident programs, such as
Sidekick on IBM PCs, were an attempt to get around the lack of multi-tasking.
The attempt was only moderately successful, and such programs often
interfere with each other and the program they preempt. Microsoft takes
the position that such programs violate the rules of MS-DOS and has warned
for years that they will not work under future versions of MS-DOS. They
won't work under OS/2, but OS/2 offers multi-tasking, so they will not be
needed.
PC spooling programs, which must patch into interrupt locations and
store into the operating system, have similar problems. (Try to get
a printer spooler and a plotter spooler both running at the same time.)
Even desk accessories on the Mac, which are officially supported by the
operating system, are something of a kludge internally.
So what we see, on the systems that don't offer multitasking, are
attempts to achieve it through hacks that don't work too well.
John Nagledillon@CORY.BERKELEY.EDU (Matt Dillon) (12/25/87)
> PC spooling programs, which must patch into interrupt locations and >store into the operating system, have similar problems. (Try to get >a printer spooler and a plotter spooler both running at the same time.) Not only that, but things like ethernet drivers for, say, a PC-AT, really screw up when you re-route LPT1: over the network to another IBM-PCAT (the plotter is connected to just one machine). Many application programs are "smart" and spool output requests, which is not only incredibly slow with two cludged semi-interrupt driven drivers talking to each other, but usually incompatible. The results are poor performance and lost connections (for no reason at all!). So much for networking an IBM-PC. This problem does not occur in a multitasking enviroment. I would say that just about everything that is a big cludge on the IBM fits right into the multitasking scheme, and I would like to add that when I say 'multitasking', I'm talking about something that is completely integrated into the OS (like the Amiga). Anybody can write interrupt driven task switchers! I've done so on the IBM, and even my old PET. -Matt