After a backspace the displayed line characters are sometimes corrupted.

Started by David Goadby, November 10, 2012, 02:39:42 AM

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David Goadby

My A13 has an odd VGA display problem which seems to occur after a backspace keypress. I have had this problem in pico and also on the command line.

During a line edit, if I backspace a few times, then sometimes the displayed characters seem to lose a few pixels. Once the pixels are lost then re-typing the characters does not correct the problem.

The odd thing is the corrupted line scrolls up the screen so it looks like the data is in a screen buffer.

It's not obvious what the problem is; it might be hardware or a screwed buffer.

Unless others are getting this problem then I will fire up a second board and see if I have a hardware issue.

TranceTrouble

your not the only one with the problem, if you display a picture the size of the output device (800x600) and clear the screen with the clear command it sometimes leaves a few lines standing at the bottom.

David Goadby

I think this is partially a hardware problem. Today my office was a lot colder than normal and the problem of corrupted characters was much worse than before. Even backspacing a whole line left pixels on the screen.

Also, when scrolling the text screen (lots of Enter presses) the faulty pixels were persistent in the same part of the screen.

I now notice, as my office (and me) is warming up, that the pixels are changing with no input from me at all.

Some 20 minutes later the screen is much better - but still not perfect.

Putting my hardware hat on I would say this is possibly a video memory timing issue. I wonder if there are A13 settings in this area which can be changed?

David Goadby

I did consider that I had a bad A13 with, maybe, a memory problem. However, I have now tried my other A13 board and the problem is the same.

It really makes console entry a PITA sometimes and I would be more comfortable ordering 50 more A13's if this was fixed.

Do Olimex accept this is a problem and is anyone looking at this?