However if I run a C64 deadtest cartridge, such as this..... IMG_20230118_151616.jpg Something totally different occurs. This deadtest cartridge operates in Ultimax mode. I do believe that this particular version bypasses the CHAR ROM chip all together and generates it's own custom character set. No...

Now if I run a diagnostic cartridge program such as this... IMG_20230118_150037.jpg Or this...... IMG_20230118_153227.jpg I think there is an TOD error on one of the CIA chips in this image. I think it's because the MOS 8520-A CIA is meant for an Amiga computer. I understand that the TOD circuitry i...

Hi rmzalbar, Following on from you hypothesis of a corrupted CharROM chip, I made some observations of the lines generated by the C128 computer on the the screen. Here is the problem. Lines in the character display area of the C128 & in C64 modes. Resizer_16738515366551.jpg Resizer_1673851536655...

Hi rmzalbar,


Both very probable causes, thanks for your thoughts. I will investigate and report back.

Hi Gyro Gearloose, I really appreciate all your help! Thanks. Yes, it looks encouraging. There are some issues. I think you are right about the jelly bean logic chips. It does seem like the main chips are working thankfully. I'm only mediocre hobbyist at best. I have been studying hard about what is...

Something interesting happens when I plug in a game cartridge like Avenger in.

The games appears to behave completely normal. Joystick, sound and graphics look fine. Note that there are no vertical lines on the screen.

Hi Gyro Gearloose, I will include some images. I have checked the power supply power and I get 12.02v and 4.94v respectively. It is interesting to note that when I type in a small program in C128 mode I get a program listing that has the line numbers all scrambled. The program will run for a short t...

Thanks Melon!

Perfect

Hi Melon,


Thank you very much for this. Very much appreciated.

Maybe I'm using up too much storage. Is there a way I can cut back some of my uploaded files?
I'm happy to delete some older posts too. I am sure that they aren't needed any more.

Any helpful tips would be kindly received.

This is the error I get when I try to upload a file.



'ERROR
Sorry, the board attachment quota has been reached.'