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
