RE: More Omega Race notes

Hey, Andre
        I'm no expert on these boards yet, but given what you just told
me, It does sound vector generator realatd. If the CPU was putting bad
data into the vector ram, the generator would complain, and you would
reset.

        
        if the sign bit goes flakey, X will try to draw all over the
place, on that y axis, but I think the vectors would more likely only
flake out on to just the other side of centre. If they are going way
back, to the left, this may not be the problem. I would scope out, or
put a logic comparitor on the 174 at D6. Then look at C4 or C3, as they
also affect the Most significant bits going to the ad851j.

        Problems with the MSB's will give the most significant change in
the vector locations. Since this appears only when you are at the
farmost right, all, or most of the X bits will be high.

        Another, but unlikey, possibility is that the TL082 at 8C8 is
misbehaving.

        The fact that it is only happening to the ship puzzles me. I
have to assume the ship comes from a ROM somewhere, and it's orientaion
and position some how makes it into the vecor ram, and is drawn. Then
getting corrupt coming out of RAM????

        Finaly, look at the Power supply. I seam to recall reading a
note somewhere, that a marginal power supply was causing oddities on the
screen. Perhaps too many vectors being drawn too far right is messing
with tl082?

All rambling at this point of course, but as I said on CGCC I will keep
my eyes open.

Mike

-----Original Message-----
From: owner-vectorlist@vectorlist.org
[mailto:owner-vectorlist@vectorlist.org] On Behalf Of andre
Sent: Friday, November 14, 2008 3:13 PM
To: vectorlist@vectorlist.org
Subject: Re: VECTOR: More Omega Race notes

Mike, you said you had a bad output in one area..
I have a boardset that works fine, but has random vectors when I shoot,
or run the ship into 'only' the right vertical wall barrier. If I hold
down the thrust and bounce against the right wall.. the ship sorta
breaks up and a line of vectors goes horizontal across the screen. It
'only' happens on this rightmost wall. Do you know (I am hoping from you
fixing one particular area on the gamescreen) which part of the circuit
may be responsible for this are? Or is this not how it works?
Looking for any help on finally solving it...
Thanks

--- On Fri, 11/14/08, mike.ranger@arcelormittal.com
<mike.ranger@arcelormittal.com> wrote:

> From: mike.ranger@arcelormittal.com <mike.ranger@arcelormittal.com>
> Subject: VECTOR: More Omega Race notes
> To: vectorlist@vectorlist.org
> Date: Friday, November 14, 2008, 9:50 AM Working on my second boardset

> now. Started by fixing acid damaged areas, then plugged in the fluke
> 9010a.
>
> I worked a fair bit to finally get it to read the ROMS, and then the
> RAM SHORT on the 2 sets of ram (4000-4BFF and 8000 to 8FFF).
>
> Once I got those to work ( and ram short did find a problem with the
> third test, an address line was not working).
>
> I then figured I was on to the vector generator. I had a bad looking
> output from x and y, top left only, small trapaziod.
>
> Spent a fair amount of time tracing back to bad opcodes, and
> eventually I figured the vector RAM was not getting the proper
> information. Looked all over the place, then noticed I was resetting
> every 2 seconds. D'oh.
>
> I went back to the 9010a and ram short was still working fine, so I
> tried RAM long on the cpu mem (4000-4BFF), all is well.
>
> Tried RAM LONG on 8000 to 8FFF, and the fourth algorithm failed. Some

> pattern thing.
> To isolate it as a RAM chip, or an addressing issue, I tried RAM LONG
> on
>
> 8000-83FF - Fail Wrote FF read FE
> 8400-87FF - PASS
> 8800-8BFF - PASS
> 8C00-8FFF - PASS
>
> Looks Like I have a problem with one chip. Used the manual's self
> test screen capture to figure where the chip was, swapped it.
>
> So I think I am now on to problems in the vector generator.
>
> One neat thing, for looking at the self test results on the bench, I
> too an old connector from a williams machnine, which has the punch
> down wire conections, and punched down an LED and put it on the header

> for the sound board, now I can see the self test flashing the start
> LED's for diagnostics.
>
> Mike

      
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