"By my arithmetic, January 1, 1900 + 143 years = January 1, 2043".
Ummm ... Did you forget the year 1900? Theres only 142 years left after you subtract the Year 1900. "How are those bits numbered? 0 to 103? What's the value of bit 0? What's the value of bit 103?" Yes, 0 to 103. Bit 51 is incremented every 1 microsecond. Carries are propagated out of bit 0. Joe On Fri, Dec 28, 2018 at 8:32 PM Paul Gilmartin < 0000000433f07816-dmarc-requ...@listserv.ua.edu> wrote: > On Fri, 28 Dec 2018 18:18:51 -0600, Joe Monk wrote: > > >So if you read the POO, you see: > > > > - Communication between systems is facilitated by establishing a > > standard time origin that is the calendar date and time to which a > clock > > value of zero corresponds. January 1, 1900, 0 a.m. Coordinated > Universal > > Time (UTC) is recommended as this origin, and it is said to begin the > > standard epoch for the clock. > > > > - The time-of-day (TOD) clock provides a high- resolution measure of > > real time suitable for the indication of date and time of day. The > cycle of > > the clock is approximately 143 years. > > > > - The TOD clock is a 104-bit register. > > > How are those bits numbered? 0 to 103? What's the value of bit 0? What's > the value of bit 103? > > >So, January 1, 1900 + 143 years = January 1, 2042, which is when the 104 > >bit clock will roll over, and bit 0 will return to zero. > > > By my arithmetic, January 1, 1900 + 143 years = January 1, 2043. > > Doesn't forcing bit 0 to 1 as described below restrict the cycle of the > clock > to 71 years rather than the 143 years from 1971 to 2114 stated below? > > >On Fri, Dec 28, 2018 at 5:06 PM Paul Gilmartin wrote: > > > >> In: MVS Interactive Problem Control System (IPCS) Customization > >> Version 2 Release 3 SA23-1383-30 > >> > >> I read: > >> TOD Clock Service > >> The time-of-day (TOD) clock service provides a caller, including > your exit routine, > >> with a TOD clock image. In the clock image, bit 0 is set on to > allow the service to > >> handle values from May 11,1971, at 11:56:53.685248 to January 25, > 2114, at > >> 11:50:41.055743. > >> > >> ??? > >> But in PoOps I see > >> ... > >> If the programming support uses the standard epoch, bit 0 of the > clock > >> remains one > >> through the years 1972-2041. (Bit 0 turned on at 11:56:53.685248 > (UTC) > >> May 11, 1971.) > >> > >> I'm inclined to believe the latter, and that Bit 0 returns to 0, not 1, > in > >> September, 2042. > >> Is there an error in the IPCS doc? > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
