On 8/14/19 5:29 AM, Raphaël Jacquot wrote: > Le 14/08/2019 à 08:18, Vernooij, Kees (ITOP NM) - KLM a écrit : >> And: don't write unnecessary code. >> A nice example is how to determine leap years: from as long as I >> program the flow is: >> - dividable by 4? >> - dividable by 100? >> - dividable by 400? >> >> The last 2 are completely unnecessary until the year 2100. >> How many useless instructions will have been executed for this reason >> in the 150 years until 2100? >> How much of our assembler code will live until 2100? Lots were not >> even prepared for 2000. >> >> Kees. >> > > that's what they said in 1965 when they were storing years in dates on > 2 digits... > hilarity ensued in 1999 when they were all panicked that their 1964 > vintage cobol code world would crumble... > > my 0.02€ > > Raphael > ...
To be fair to history, in 1965 most had good reason to expect that assembly code would be short-lived. Prior to the announcement of S/360 in April 1964, almost every time you had to upgrade to a newer or faster processor the hardware architecture changed enough that you had to completely rewrite assemblly code every several years. S/360 guaranteed compatibility for performance upgrades within S/360, but didn't rule out incompatible future architectures. In 1965, even those exposed to S/360 would have had no experience yet to make them assume the architecture would be stable enough and kept as a subset of future architectures to allow running the same code decades later, much less have z-architecture hardware supporting the same instructions as a subset in 2019. Joel C Ewing -- Joel C. Ewing ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
