[Simh] Enhancement Request: Additional Built-In Variable

[Paul Koning]

On Jan 10, 2019, at 1:56 PM, Robert W.Mills <rwmills.uk at gmail.com> wrote:
> 
> I don't know about the operating systems used by the other simulators
> but MPE V (used by the HP3000 simulator) is not Y2K compliant.
> 
> Is it possible to have a built-in variable, possibly called something
> like %DATE_YY_DIF%, that holds the difference between %DATE_19XX_YY% and
> the actual year as held by the host operating system? For example,
> %DATE_19XX_YY% is returning the value 91 for this year. In this case
> %DATE_YY_DIF% would hold 28 which is the difference.
> 
> %DATE_YY_DIF% could then be used to translate dates from internal
> (simulator) to external (user) by adding the value to the internal year.
> Translation from external to internal is just a matter of subtracting
> the value from the external year.
> 
> The need for this request would disappear if the HP3000 simulator could
> not use it.
> 
> David, is it possible to set a JCW with this value when a session starts?

There are plenty of operating systems we could run on SIMH that aren't Y2K compliant.  Some even have date issues earlier than 2000 (DOS-11 for example).

But I don't see how SIMH can help that.  Y2K is a software issue; SIMH is simulating the hardware.  How would SIMH know that some particular bit of output from the sofware is a date?

The one place where offsets might work is if the emulated hardware includes a calendar clock, for example as seen in some late PDP-11 models.  If so, one might imagine a SIMH variable that tells it to pretend the year is earlier than the real one.

	paul