The CLK signal is a full TTL level output from the 8085, derived from the clock generated by the crystal. It is half of the crystal frequency - Confirming that your 4.9152 Mhz crystal is running happily.
Your counter may simply not be sensitive enough to detect the crystal signal directly, or it may place too great a load on the crystal. I would use an oscilloscope to look at the crystal voltage directly. But as I said above, you don't have to because you have confirmation that your oscillator is running. If you can see a 2.458 Mhz signal on CLK, then it means that your crystal is absolutely oscillating. You can simply check by gently lifting one leg of the crystal, and your 2.458 Mhz signal will go away. Kindest regards, Doug Jackson em: [email protected] ph: 0414 986878 Check out my awesome clocks at www.dougswordclocks.com Follow my amateur radio adventures at vk1zdj.net ----------------------------------------------------------- Just like an old fashioned letter, this email and any files transmitted with it should probably be treated as confidential and intended solely for your own use. Please note that any interesting spelling is usually my own and may have been caused by fat thumbs on a tiny tiny keyboard. Should any part of this message prove to be useful in the event of the imminent Zombie Apocalypse then the sender bears no personal, legal, or moral responsibility for any outcome resulting from its usage unless the result of said usage is the unlikely defeat of the Zombie Hordes in which case the sender takes full credit without any theoretical or actual legal liability. :-) Be nice to your parents. Go outside and do something awesome - Draw, paint, walk, setup a radio station, go fishing or sailing - just do something that makes you happy. ^G ^G ^G ^G ^G ^G ^G ^G- In more laid back days this line would literally sing ^G ^G ^G ^G ^G ^G ^G ^G On Mon, 19 Oct 2020 at 04:59, Stephen Adolph <[email protected]> wrote: > Fantastic. Well is the cpu has 5V and there is no clock at pin 37 > then...I would change the crystal. > Of course the CPU needs ground. > > The crystal is fully passive > If there was a problem with the connections on pin 1 or 2 that could also > do it > > > > > > On Sunday, October 18, 2020, Charles Hudson <[email protected]> wrote: > >> Examining documentation for the Model 102 I found that the clock signal >> is on pin 29 and a usable ground on pin 22. With some wire-wrapped pins >> and kynar AWG30 I hooked the 102's bus up to the frequency counter. With >> the 102 power off the frequency read 0. With power on it read 2.458426 >> MHz. I think we have established that the counter is capable of counting. >> >> The question remains why the Model 100 80C85 is not clocking: Is the X2 >> crystal at fault or is power not getting to the crystal? Part of my >> problem is that I don't know where to probe for voltages. Suggestions >> welcome. >> >> -CH- >> >> Pics of the test setup: >> https://drive.google.com/file/d/11MY_V3-GAxTM3Pon__NEGR0pZzyrppx-/view?usp=sharing, >> >> https://drive.google.com/file/d/17opAgMdcpcEL_T_bLqT2AK1xe1yObKfV/view?usp=sharing, >> >> https://drive.google.com/file/d/1zqKWYKAxFqBcQ9c3CaxttLbERHVt5FSQ/view?usp=sharing >> >> >>
