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<DIV><FONT face=Arial size=2>When I write to a location in video memory, say
8010 with a value of 44. I get on screen two characters. It appears
that either the data is being written to two adjacent memory location which is
doubtful or the circuit that reads the data out is getting only even (or odd,
not sure yet) columns. A second symptom of this is that when I run a
program I wrote on the 9010 to set the video memory range I get a delay between
changes on the screen equal to the time it takes to fill one row, looks like it
is writing it but nothing visible is happening.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>This is a problem that I actually do hate to
diagnose because the video address space is always being run its hard to tell
what's going on.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I think your probably right about the address
line. Unfortunately the playfield generator on this board is more than a
little complex.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>For those who want to follow at home, its sheet 7A
of the schematics. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Oh and the "dirt" is a static picture contained in
rom 9N (#114). I pulled the rom and no dirt distracting me from seeing my
nice double chars :)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>David</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=rlboots@cedar-rapids.net
href="mailto:rlboots@cedar-rapids.net">Rodger Boots</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=rasterlist@synthcom.com
href="mailto:rasterlist@synthcom.com">rasterlist@synthcom.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, November 17, 2002 1:16
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: RASTER: Dig Dug memory
map</DIV>
<DIV><BR></DIV>David Shoemaker wrote:<BR>
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<DIV><FONT face=Arial size=2>Anyone know just where the background (dirt)
hides in the memory map? I am working on a board with double chars in
the foreground and am wanting to clear the screen to try and figure out
where the oddities are coming from. But I am not able to find the
right memory range to wipe the dirt.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Of course I just had a thought. Is the
dirt a constant that gets painted over with chars? Which would mean it
comes out of rom as a static picture. Anyone?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>David</FONT></DIV></BLOCKQUOTE><BR>I would think
the dirt would be the "playfield" which is shown when MOBJ0-MOBJ3 are all
high. The playfield RAM is from 8000 to 87FF.<BR><BR>But you probably
knew that, and I've never had to work on one so that's about as much help as
I'm likely to be.<BR><BR>What exactly do you mean by "double characters"?
Sounds like an address line not toggling.<BR><BR><PRE class=moz-signature cols="$mailwrapcol">--
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Received on Sun Nov 17 09:32:47 2002
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