Funky Characters

4 posts / 0 new
Last post
Offline
Last seen: 5 months 1 week ago
Joined: Dec 20 2018 - 17:45
Posts: 2
Funky Characters

I decided to pick up my dads apple //e around Xmas and try it out.
But it turned out to have some character problems.

"E" looks like" [" ," p" like "r", "a" is solid  and so on. 
Has someone an Idea what could be the problem with the machine?
Best Regards and Happy Xmas!


 

Online
Last seen: 36 min 24 sec ago
Joined: Jul 5 2018 - 09:44
Posts: 300
Probably either a bad VIDEO

Probably either a bad VIDEO ROM or possibly one of the other chips.

 

Offline
Last seen: 1 month 2 weeks ago
Joined: Nov 8 2018 - 15:49
Posts: 20
Sounds like a good candidate

Sounds like a good candidate for some fun troubleshooting!  First thing is to determine whether it's the keyboard, or the video circuit.  (It's probably the video circuit if you're seeing inverse characters).  You can figure that out by typing "LIST" (or any other valid command) and see what happens.  Of course you won't see "LIST" on the screen but press <Return> anyways, and you want to check if you get a syntax error.  If you get a syntax error, then the problem is the keyboard didn't really send "LIST" to the computer.  If you don't get a syntax error, then the problem is the video circuit (keyboard sent "LIST" to the computer but video didn't display it correctly)..

Also, if the characters are consistently swapped ("E" is *always* a "[", etc.), then you might look at the tables of characters (either for keyboard or video, depending on where the problem is), and see if there is a particular bit in the character code that is always swapped.  That could lead to some insights.

Good luck!

Offline
Last seen: 5 months 1 week ago
Joined: Dec 20 2018 - 17:45
Posts: 2
THX

The keyboard is fine. I'll replace the video ROM.

Thank you for the help!
 

Log in or register to post comments