Denial

Hi eslapion, Apologies for mistakingly thinking the trigger voltage of my observations should be TTL level or about 1.3-1.5v. Your statement was taken out of context. I must have made a false sense of connection when I saw my trigger level gave the best observations when set to 1.4v. Hypothetically ...

Hi levoman, I have a cheap usb logic analyzer ( it's only 8 channel ) , never used it yet ,but ,that was my next goto! Will give it a try and see if it is worth it or not. Love the scope banman just the sort of thing i like! Thanks. I like it heaps. It's very tactile. I imagine that you feel the sam...

Hi eslapion, I have been getting more familiar with the controls. I this time set the trigger level to 1.4V. The sweep time is 100ns and the Volts per division is 500 mV. Again I am observing a Winbond W27c512 EEPROM. I should have mentioned that I am running a 10x probe as close as practical to pin...

Hi eslapion, Apologies for the delayed response. I was thinking about what you said. Thank you on the clarification on RMS. It is not required for these observations.😁 I think I've been able to remove RMS Measure and inserted MIN & MAX (I took me a little bit to get this up). These pictures were...

Hi eslapion and levoman, WOW! That's impressive at what you've achieved levoman. I'm out of my depth here. I'm trying to follow along as best as I can :D. I am keen to know more! The trigger should always be at TTL level or about 1.3-1.5v. That's a good piece of information with the results I am loo...

What I might do is break out the oscilloscope and take some readings on this unmodified KU style mainboard.
My oscilloscope is an old steamer...

I'll post some observations......

Hi levoman, Thanks for sharing your test results on the non ST based EPROMs. You might want to reference them on your PCBWAY project. 😁 I don't think I would have ever tried to test these other brands I had here..... Regarding this pictured KU style board. I personally have done nothing but replace ...

Hi levoman, I have been doing some more testing of other chips. I thought I had more 27C512 EPROMS. unfortunately a majority of them are 256kb and lower capacity chips. I tested the following chips on a C64 Mainboard KU 141194HB with original 200ns memory. These original chips don't work. However th...

Hi levoman, Holy cow! I've actually got chips like those! I never tested them.I am sure I've got photos of them on Melon64 thread. https://www.melon64.com/forum/viewtopic.php?f=12&t=8691&start=50 Fairly sure I have AMD, Texas instruments and Intel ones too. I only investigated the one that w...

Hi levoman, Nice work on your PLA replacement PCB! :D I used Winbond W27C512 EEPROM, a Commodore Factory PLA and a 27C512 E/PROM to ensure that my latch circuit had the appropriate 74LS279 Quad Set-Reset Latch. The Winbond W27C512 EEPROM I had was absolutely not suitable as a E/PROM based PLA soluti...

Hi levoman, I totally understand your concern..... Your oscilloscope will be plenty fine for viewing the PLA glitch. If you made the cartridge you could use your oscilloscope and do a side by side comparison of the 2. The worst case being your version of the Zaxxon cartridge won't detect the PLA gli...

Hi levoman,

Do you, by chance have access to an oscilloscope?

Hi eslapion, Above all, stay away from any logic ICs sold on eBay coming from China. Very often, the chip inside isn't at all what it says on the package. Then you ask yourself why it is you get inconsistent results. That statement I absolutely agree on.... levoman if you are at all concerned about ...

Hi levoman,


Looking forward to you posting your project.


I hope your prototype PCB's work out for you.

Don't stress too much about copyright issues with your project. I am sure nobody will bother you

Hi eslapion, Thanks for the links on the cartridge edge connectors. :D I have been looking everywhere for articles that explain the correct methods of making the edge connectors. I had gone about making mine the worng way. :oops: Beveled edges and using the hard faced gold (I think the correct term ...