lucasp

Thats sound like good idea. I will do that as soon as i find some idle time.

It was loaded from the disk

Recap of what was done: Replaced all the big chips including ROM from a working system MMU has been swapped Memory chips have been installed from a working system Different keyboard was used Address lines verified from CPU to Memory addressing chips Re soldered address line joints XL self test shows good SALT RAM test shows good Basic XL gives error -14 when hitting enter. Mac/65 gives an inverse-heart symbol, syntax error Ballblazer came up and looks normal Zorro booted and played music, but the screen was corrupted...

I have used different keyboard. The solder joints on the board look clean and untouched. I have also re-soldered address lines from CPU

I have swapped the ram from working Atari.

Yes i have replaced PIA and MMU

That would be great, i could stop by after Wednesday (short drive from London) bring the board and check it.

I have tested the big chips on other board and vice versa and all of them are performing fine. I will try the mmu

When i run basic from the rom chip it behaves the same way as if i ran the basic from cart. Would that still be a valid statement?

Thanks for the offer, I am in ShothWestern Ontario

I will have to source one up to test it. Most of my chips on this board are in the sockets. But my working system has them soldered in.

I have already tried different keyboard, ram, and POKEY chip with no luck.

All the tests in diagnotics are passing green.

This causes system to freez with blue screen and READY displayed, but no reset

Typing FRE(0)+RETURN creates white screen BYE+RETURN black screen Running basic from catriage i cant not reproduce the "code dump" and pressing RETURN key causes reset to black screeen

I only have the computer, no floppy or tape yet. When I have basic cartridge inserted the RETURN key does not reset the system but produces a code dump

I am looking for help/pointer how to fix my 800XL. The symptoms are very strange. The computers powers on and displays “READY” you can type anything and everything is fine until you press the ENTER key then the system resets to a black screen and freezes. I have tried different keyboard but no luck, build in diagnostics is green. Any help would be appreciated.