Brian Gregory wrote: > > In-Reply-To: <4042F7084FCDD311834B00104BCA47700B86EE@MAIL2> > > John Orhan wrote: > > I have seen a circuit where a 4Mhz Z80 was clocked at 10Mhz with the > > addition of a 10M parallel resistor across the Xtal. I don't know how/why > > this would work but am dying to find out. > > This doesn't make sense. > > The 10M resistor can't have anything to do with the overclocking. > > For a start you don't connect a crystal directly to a Z80. It needs an > external clock oscillator. OK, I had to do an archival search of my old hard drive and found the mention of the 10 Meg resistor. Who needs a good memory, when you have a search command. :-) ================================================================ Most 84s can be speed up to 8Mhz, but note that this doesn't comply with manufacturers specs. Tin canned, 4 legged TTL Oscillators may speed it along at 12Mhz too, but watch out for internal EEPROM read/write cycles! Gary Barnes of Western Australia put me onto the 12Mhz Oscillator trick. Other users have told me that you can get some 4Mhz PICs running at 16 and 20Mhz by just putting a 10Meg resistor across the faster cyrstal. Don McKenzie mailto:don@dontronics.com http://www.dontronics.com World's Largest Range of Atmel/AVR and PICmicro Hardware and Software. Free Basic Compiler and Programmer http://www.dontronics.com/runavr.html