[pups] Default P11 Emulator Clock Rate

Frank Wortner frank at wortner.com
Thu Oct 5 04:37:09 AEST 2000

This is just an FYI for anyone playing with the Begemot P11 emulator ...

The default clock rate on P11 is 50 Hz.  While this corresponds to AC line
frequency in many parts of the world,  it is not correct for the
U.S.,  where 60 Hz is the norm.  Since PDP-11 Unix was developed in the
U.S.,  the bootable distributions probably assume a 60 Hz clock
also.  When the software and "hardware" disagree on clock rates,  problems

My emulated 11 had difficulties keeping accurate time until I discovered
the 50 Hz clock rate.  After I changed it to 60,  the emulator's time was
remarkably accurate!

If you want to change the default clock rate,  you can do so in the source
(look for the symbol "clock_rate" in "main.c"),  or you can just add

	set clock_rate 60

into your p11conf file.  This will override the default in the emulator

Have fun -- I certainly am! :-)


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