Commodore 128 Alive!

Other Commodore Computers => Plus/4 & C16 => Topic started by: marquisor on January 25, 2011, 06:18 AM

Title: Clockspeed of +4
Post by: marquisor on January 25, 2011, 06:18 AM
heya!

just a very short question:

what is the clock speed of the plus/4?

some sources say 1,10 MHz, some say 1,79 MHz, some say the higher MHz (1,79) must be enabled via a programming trick?
so what's true then?  and how "hard" is it to do a programming trick to get the 1,79 MHz steadily running

thx!
maq
Title: Re: Clockspeed of +4
Post by: bacon on January 25, 2011, 05:03 PM
OK, I'm not 100% sure of any of this, but I seem to remember that it runs at 1.79 MHz but it is slowed down to 1.10 MHz during certain operations (I/O access?).

Edit: A quick check at the Plus/4 World (http://plus4world.powweb.com) forums confirms part of this. It's basically the same as with the C128: it normally runs at the slower speed but if you turn off the screen you get the higher speed.
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