cj7hawk
Veteran Member
I read an echo. Are you two twins?
And from two accounts, one with just 8 posts... I'm curious about that too... A fault in the system maybe?
I read an echo. Are you two twins?
Correct. If you're not seeing those characters in the first position of the screen, that indicates the ROM is not being executed.Hi, yes the pic is for the 2x, the picture of the II I've already uploaded. Ok, I'll check again the continuity for all the main chips. I know that your roms don't clear the screen, but I think that with the monitor rom, there's is an "a" and a "b" switching on the first position, and a count between 1 to 9 in the memory rom, it's ok??
Hi people,
I've checked all the schematics with the motherboard and ALL the connections are fine.
Hi everybody again, I've been trying to fix the kaypro again..
But no success
I've socketed all the memory and memory video chips. One 4164 was bad , but it doesn't fix the issue.
The screen is full of garbage when the computer start.
I've seen in the tech manual that garbage on screen can be a problem with the reset switch but it seems that there's no short in the switch, but it doesn't work at all.
The lights of the drives still on all time, I don't know it it could be a clue.
So, please, be patient with me, I have a basic knowledge about electronics. I have a pocket oscilloscope, so please can you tell me in a very basic way where can I start to search for the problem??
As you earlier say perhaps the /CE and /OE of the rom could be a good starting point??
Thank you all!!
Sorry, you've misunderstood me - I'm not suggesting that the z80 is faulty ( though it might be ) - I'm suggesting that the first point in troubleshooting a z80 system that is not working is to check that the z80 is doing what it is supposed to be doing - eg, reading and writing data, and that all the signals to it look correct. Then you track this back to memory to make sure what it is seeing is correct - is it reading the rom and executing? Is it getting a good clock? At the right frequency? Is it clean? Are you seeing the right pins strobing? Are any held low or look weird compared to other similar pins?Hi, thank you!! I'm sure that the Z80 work in other computers, but I'll test it again. And yes, durgadas has several monitor roms but I'm afraid that the computer even doesn't run the rom.
Gotcha!! I'm afraid that it can be easy from the beginning, doing the things well, but at least I fixed it. Now I have a problem with the keyboard but this is another story.. The 20 MHz cristal was broken.. Many thanks to everyone, I really appreciate your effort
Thank you all