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

Reply via email to