Shared TOD clock modification bit

Details Shared TOD clock modification bit Shared TOD clock modification bit

1981-11-10

1983-06-14

Gruber, Felix D.

Boots, shoes, and leggings

371 61, G06F 1100

Patent

active

043886884

ABSTRACT:
A shared time-of-day (TOD) clock modification bit is used in a multiprocessing system in which the timing facilities in two or more CPUs are implemented as a function of a single TOD clock. This bit helps avoid timer errors that occur as the result of one central processing unit (CPU) changing the TOD clock value while another CPU is executing an instruction which determines a CPU timer value. Whenever the microcode in any one of the CPUs reads the TOD clock, it obtains the Shared TOD Clock Modification Bit in addition to the TOD value. This bit indicates if the TOD clock read operation just completed is the first such operation executed by that CPU since the TOD clock was updated by another CPU sharing the same TOD clock. If it is, certain instructions take action to correct timer errors introduced by the change in the TOD clock value.

REFERENCES:
patent: 3248707 (1966-04-01), Paul et al.
patent: 3408629 (1968-10-01), Haselwood
patent: 3761884 (1973-09-01), Avan et al.
patent: 3932847 (1976-01-01), Smith
patent: 4112500 (1978-09-01), Peters
patent: 4121286 (1978-10-01), Venton et al.
patent: 4349890 (1982-09-01), Chang
IBM TDB vol. 17, No. 7 Dec. 1974-pp. 2043-2045.

Affiliated with

Also associated with

Rating

Shared TOD clock modification bit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Shared TOD clock modification bit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shared TOD clock modification bit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-167397