Appeal 2007-2127
Reexamination Control No. 90/006,621
executing incremental portions of their respective subtasks in different parts
of the program. As noted in the claim interpretation, this is consistent with
the '604 patent's description of multithreading ('604 patent, col. 1,
lines 45-53) and with independent claims 1, 18, 22, and dependent claim 25,
which recite that the threads alternate and perform successive incremental
portions of their respective subtasks, meaning that both threads are executing
at the same time except for the threads switching back and forth.
The "interrupt" operation disclosed in the 1982 application does not
involve "concurrent execution" of the compiler main program and the editor
interrupt service routine. The main program is stopped when an interrupt
occurs and does not begin running again until the interrupt service routine
program finishes. Thus, the main program can never "execute" at the same
time as the interrupt service routine. This is an example of "sequential
operation" because the main program can never run after the interrupt
service routine has only executed part of its task. If the editor interrupt
service routine could be interrupted by second editor routine, its execution
also would be completely halted until the second editor routine finished. By
contrast, in a "preemptive multithreaded" system, a first thread runs for a
timeslice, a second thread runs for a timeslice, the first thread runs again for
another timeslice, and so on in alternating fashion. Thus, both threads
execute at the same time, but for the need to alternate access to the CPU.
This operation is possible because of the design of the operating system.
Hardware interrupts as disclosed in the 1982 application were well known,
as evidenced by De Jong infra, but were never termed "multithreading."
For this additional reason, we find that there is no written description
of "preemptive multithreading" in the 1982, 1985, or 1990 applications, and,
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