Re: Robotron Tech: Lines at top of screen

b1bbet@xxxxxxx wrote:
On Jan 31, 1:36 am, jrok <jrok...@xxxxxxxxxx> wrote:
In article Ratsputin says...



I've seen this before and believe I've read some articles on it as
well. This is a fundamental issue with the architecture used by
Williams. Basically, some of the scratchpad RAM being used by the
program is being scanned by and displayed by the video circuitry.
Defender has the same issue.
That's what happens on the horizontal, where' they're using video RAM as
scratchpad and you get the interesting effect at the right edge of the screen.

In this case it's caused by the game writing to the color RAM. As the original
hardware didn't have vertical blanking the writes to the color RAM will show up
on screen. During normal operation it's synchronized to the top of the 4msec
interrupt so it's hidden way at the top of the screen and hidden.
Complex fix.. add a blanking circuit (!!!) Easy fix adjust the monitor so it's
hidden off the top of the screen ;)

- James

--
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JrokLandhttp://www.jrok.com
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Upon double checking, it's actually just below the scores - so moving
it off the screen isn't an option. :(

How complex is the blanking circuit?

Adjust your vertical height/width. Sounds like you have foldover.
.

Relevant Pages

  • Re: Robotron Tech: Lines at top of screen
    ... some of the scratchpad RAM being used by the ... That's what happens on the horizontal, where' they're using video RAM as ... add a blanking circuit Easy fix adjust the monitor so it's ...
    (rec.games.video.arcade.collecting)
  • Re: Robotron Tech: Lines at top of screen
    ... some of the scratchpad RAM being used by the ... That's what happens on the horizontal, where' they're using video RAM as ... add a blanking circuit Easy fix adjust the monitor so it's ...
    (rec.games.video.arcade.collecting)
  • Re: Robotron Tech: Lines at top of screen
    ... some of the scratchpad RAM being used by the ... That's what happens on the horizontal, where' they're using video RAM as ... add a blanking circuit Easy fix adjust the monitor so it's ...
    (rec.games.video.arcade.collecting)
  • Re: Robotron Tech: Lines at top of screen
    ... some of the scratchpad RAM being used by the ... That's what happens on the horizontal, where' they're using video RAM as ... hardware didn't have vertical blanking the writes to the color RAM will show up ... add a blanking circuit Easy fix adjust the monitor so it's ...
    (rec.games.video.arcade.collecting)