Ex parte CUTTS et al.

Board of Patent Appeals and Interferences

Aug 31, 1998

08116950 - (D) (B.P.A.I. Aug. 31, 1998)

Application for patent filed September 7, 1993. According1
to appellants, this application is a continuation of Application
07/517,533, filed April 25, 1990; which is a continuation of
Application 07/282,538, filed December 9, 1988.
1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today
(1) was not written for publication in a law journal and
(2) is not binding precedent of the Board.
Paper No. 52
UNITED STATES PATENT AND TRADEMARK OFFICE
__________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________
Ex parte RICHARD W. CUTTS, JR.,
KENNETH C. DEBACKER, ROBERT W. HORST,
NIKHIL A. MEHTA, DOUGLAS E. JEWETT,
JOHN D. ALLISON, and RICHARD A. SOUTHWORTH
__________
Appeal No. 96-0905
Application 08/116,9501
__________
ON BRIEF
__________
Before KRASS, FLEMING, and CARMICHAEL, Administrative Patent
Judges.
KRASS, Administrative Patent Judge.
DECISION ON APPEAL
Appeal No. 96-0905
Application No. 08/116,950
2
This is a decision on appeal from the final rejection of
claims 1 through 8, 11 through 14 and 16 through 26, all of the
claims remaining in the application.
The invention is directed to a fault-tolerant computer
system employing multiple CPUs. Each CPU has its own independent
clock in order to avoid imposing the expense, complexity and
timing problems of typical fault-tolerant clocking. However, the
CPUs are loosely synchronized by detecting certain events and
stalling any CPU ahead of the others until all the CPUs execute
the required function simultaneously. Interrupts are also
synchronized to the CPUs in order that the CPUs all execute the
interrupt at the same point in the instruction stream which they
are all executing. More particularly, each of the CPUs has a
counter which counts machine cycles corresponding to execution
cycles but does not count stall cycles. Further, each CPU is
interrupted at some predetermined count value. All interrupts
are made to occur at the same virtual time in each CPU, though
not necessarily at the same point in real time.
Representative independent claim 1 is reproduced as follows:
1. A multiple CPU system, comprising:
a) a plurality of CPUs concurrently executing a same
instruction stream, the CPUs each being clocked
independently of one another to provide separate machine
Appeal No. 96-0905
Application No. 08/116,950
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clock cycles for each CPU, so that said instruction stream
is executed asynchronously over plural instructions and any
of said CPUs may be leading other of said CPUs, said machine
clock cycles including execution cycles where an instruction
of said instruction stream is executed and stall cycles
where an instruction of said instruction stream is not
executed, each CPU having a memory request input/output
port;
b) a common memory coupled to the input/output ports of
said CPUs, the common memory implementing a memory request
only after receiving identical requests from all of said
CPUs, the memory sending an acknowledge signal to the CPUs
when implementing a memory request, each of the CPUs
executing stall cycles while awaiting implementation of a
memory request by the common memory as signalled [sic,
signaled] by said acknowledge signal;
c) each of the CPUs having a counter to count machine
clock cycles corresponding to execution cycles but which is
inhibited from counting machine clock cycles corresponding
to stall cycles; and
d) said CPUs having an interrupt circuit responsive to
an external interrupt request occurring at any time
unsynchronized with said execution of said instruction
stream, said interrupt circuit being coupled to said
counters in said CPUs and responsive to a selected count in
each of said counters for separately interrupting each CPU
at an identical instruction execution cycle, any one of the
CPUs which may be leading being interrupted first while
other of said CPUs continue to execute instructions so that
if said CPUs are executing different instructions in said
stream then said CPUs may be interrupted at different
instants in real time.
The examiner relies on the following references:
Kreis et al. 3,921,149 Nov. 18, 1975
(Kreis)
Kolb et al. WO 85/02698 Jun. 20, 1985
(Kolb) (PCT)
Appeal No. 96-0905
Application No. 08/116,950
4
Claims 1 through 8, 11 through 14 and 16 through 26 stand
rejected under 35 U.S.C. § 103 as unpatentable over Kolb in view
of Kreis.
Reference is made to the briefs and answer for the
respective positions of appellants and the examiner.
OPINION
At the outset, we note that, in accordance with appellants’
statement at page 6 of the principal brief, independent claims 1,
3, 5, 7 and 23 will stand or fall together, and dependent claims
12, 13, 18, 20, 21 and 26 will stand or fall together. Appellants
separately argue the merits of dependent claims 12, 13, 18, 20,
21 and 26 at page 12 of the principal brief and throughout the
briefs, arguing that the instant invention’s interrupt only on a
selected value registered by the counters distinguishes over the
applied references. However, dependent claims 2, 4, 6, 8, 11,
14, 16, 17, 19, 22, 24 and 25 will stand or fall with the claims
from which they depend since appellants make no separate argument
with regard to the specific limitations added by these claims,
i.e., with regard to the common memory modules and local memories
not accessible to other CPUs.
We also note that while Kreis is applied by the examiner for
the teaching of access requests to a common memory which are
Appeal No. 96-0905
Application No. 08/116,950
5
voted, there is no argument by appellants regarding such a
limitation or teaching by Kreis. With regard to Kreis,
appellants argue only that the reference does not provide for the
alleged deficiencies of Kolb. Accordingly, for purposes of this
appeal, we will focus, as do appellants and the examiner, on the
teachings of Kolb.
With regard to the independent claims, the examiner
recognizes that Kolb does not specifically teach that the CPU
cycle counters count machine cycles corresponding to execution
cycles but not machine cycles corresponding to stall cycles.
However, the examiner points to various portions of Kolb (page 3,
line 33 to page 4, line 1; page 9, lines 17-35) indicating that
there are many alternative possible choices of processor events
which can be used as a virtual time tick for the purpose of
measuring virtual time. Therefore, the examiner concludes, and
we agree, that it would have been obvious to have counted machine
cycles corresponding to execution, but not stall, cycles in order
to measure virtual time.
In response to appellants’ argument that all the claims
require also that the interrupt signal is to be applied at a
“selected” or a “preselected” count value, the examiner points
out that in the second embodiment of Kolb, when an interrupt
Appeal No. 96-0905
Application No. 08/116,950
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signal is received by the lead processor, the location of the
processor in the program is stored and the lead processor
continues on after servicing the interrupt. Then, when a lagging
processor advances to the same position in the program, it is
also notified of the interrupt so that the interrupt is serviced
at the same virtual time by both processors. Accordingly, the
examiner considers the stored virtual time in Kolb as the claimed
“selected” or “preselected” count.
In response, appellants contend that even if the examiner’s
position, i.e., that the virtual time used to interrupt the
lagging processors in Kolb is equivalent to the
preselected/selected count of the instant independent claims, the
instant claims still distinguish over Kolb because they require
that “each” of the CPUs contains the recited interrupt circuit
and is interrupted at the preselected/selected count so that
“each” of the CPUs must be interrupted in accordance with the
preselected/selected count. Yet, the lead processor of Kolb
receives the first interrupt as soon as it is sent at some
“random” virtual time, and not at the preselected/selected time
recited in the instant claims.
We will sustain the rejection of claims 1 through 8, 11
through 14 and 16 through 26 under 35 U.S.C. § 103 because while
Appeal No. 96-0905
Application No. 08/116,950
While the language of claim 1 (“said CPUs having an2
interrupt circuit”) and claim 3 (“an interrupt circuit connected
to all of said CPUs”) might, at first glance, be interpreted as
permitting a single, separate interrupt circuit coupled to each
of the CPUs, it is clear from the disclosure, e.g., page 17, line
25 and Figure 2, that each of the CPUs has an interrupt circuit
65. This, coupled with appellants’ similar interpretation, or
admission, at page 5, fourth line up from the bottom, of the
reply brief, that the language of the claims mean that “each of
the CPUs contains the recited interrupt circuit” would make any
other interpretation unreasonable, in our view.
7
we agree with appellants’ last argument that the lead processor
of Kolb receives the interrupt request and executes it as soon as
it is sent at some random virtual time, and not at a
preselected/selected time, the instant claims are not so limiting
as to distinguish over Kolb in this regard. Since the claims are
open-ended, i.e., the multiple CPU system “comprising”..., the
“plurality” of CPUs recited in the claims need not include the
lead processor as in Kolb but may very well include all of the
processors of Kolb but for the lead processor.
We find the examiner’s approach of interpreting the virtual
time used to interrupt the lagging processors in Kolb as a
“preselected” or “selected” count to be sound. We also find that
each of the independent claims, in one form or another, requires
that each of the CPUs has an interrupt circuit and a counter and2
that the interrupt circuit is responsive to an external interrupt
Appeal No. 96-0905
Application No. 08/116,950
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request occurring at any time. It is also required that the
interrupt circuit and counter be coupled so that the interrupt
circuit is also responsive to a selected, or preselected, count
in the counter for separately interrupting each CPU at an
identical instruction execution cycle. Accordingly, even the CPU
which may be leading is also subject to the selected, or
preselected, count determining when that CPU will be interrupted.
In Kolb’s system, specifically the second embodiment relied on by
the examiner, the lead processor appears to receive the interrupt
request immediately and to service that interrupt at any random
time the interrupt request is made. The lead processor then
proceeds in the program although the specific location in the
program at the time of the interrupt is stored so as to be used
by the lagging processors in order to interrupt at the same
virtual time within the program. Therefore, as appellants’
argument goes, since the instant claims require that each of the
CPUs must be interrupted in accordance with the preselected, or
selected, count and Kolb’s leading processor is clearly not
interrupted in accordance with such a count, nor is there any
evidence as to why it would have been obvious to modify Kolb in
any manner to achieve such (and Kreis adds nothing in regard to
Appeal No. 96-0905
Application No. 08/116,950
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remedying this deficiency in Kolb), the instant rejection under
35 U.S.C. § 103 should not be sustained.
We would not sustain the rejection under 35 U.S.C. § 103 if
interpretation of the instant claims required that the leading
CPU, as disclosed by Kolb, be part of the claimed “plurality of
CPUs.” However, since the instant claims are open-ended, because
of the “comprising” recitation, it is a fair interpretation to
read the instant claims on the disclosure of Kolb with the
consideration that all of Kolb’s CPUs, other than the lead
processor, comprise the claimed “plurality of CPUs.” Then, of
course, after the “preselected” count is established by the lead
processor upon randomly receiving the interrupt request and
storing the specific location in the program at the time of the
interrupt, all of the other CPUs, i.e., those belonging to the
claimed “plurality of CPUs,” will be subject to being interrupted
“responsive to a selected count...for separately interrupting
each CPU at an identical instruction execution cycle.” The way
appellants’ “multiple CPU system” is set forth in the instant
claims, it allows for extra CPUs (e.g., Kolb’s lead processor)
not part of the claimed “plurality of CPUs” and, therefore, not
subject to the specific limitations laid out for each of the
“plurality of CPUs” in the claims.
Appeal No. 96-0905
Application No. 08/116,950
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It is our view that if appellants’ claims, in some way,
required that all of the CPUs in the multiple CPU system were
subject to the claimed requirements regarding interruption
responsive to a preselected count, this would distinguish over
the applied references for the reasons set forth in the reply
brief. However, as presently claimed, we agree with the
examiner’s rejection of claims 1 through 8, 11 through 14 and 16
through 26 under 35 U.S.C. § 103.
The examiner’s decision is affirmed.
No time period for taking any subsequent action in
connection with this appeal may be extended under
37 CFR § 1.136(a).
AFFIRMED
Errol A. Krass )
Administrative Patent Judge )
)
)
)
Michael R. Fleming ) BOARD OF PATENT
Administrative Patent Judge ) APPEALS AND
) INTERFERENCES
)
)
James T. Carmichael )
Administrative Patent Judge )
Appeal No. 96-0905
Application No. 08/116,950
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