Re: Can u help me find Secret Life of VecGen?

It is at www.jmargolin.com.

Cheers,

----- Original Message -----
From: <ygroups@timbunning.com>
To: "MyPearl" <mypearl@dds.nl>
Sent: Sunday, July 20, 2003 12:40 PM
Subject: Can u help me find Secret Life of VecGen?

> Hi Mendel,
>
> Can you tell where I can find the "Secret Life of Vector Gen" document
> please?
>
> Many thanks - Tim.
>
>
>
>
>
> "MyPearl" <mypearl@dds.nl>
> Sent by: owner-vectorlist@vectorlist.org
> 02/07/03 21:30
> Please respond to vectorlist
>
> To: <vectorlist@vectorlist.org>
> cc:
> Subject: VECTOR: Fw: Asteroids SOLUTION!
>
>
> Hello Guys,
>
> I have found the culprit!!!
>
> Thanks to Jed Margolin's very comprehensive 'Secret Life of Vector
> Generators' document, which is VERY GOOD if you really want to understand
> a
> bit about how our favorite games work, I found that the output of LS04 at
> L5
> was only swinging from 2.5 to 5 volts, it never went any lower. this
> affected the Stae Machine's VMEM handling, that is why the self-test was
> all
> okay but the game went bonkers.
>
> Im just so HAPPY!!!
>
> Cheers,
>
> Mendel
>
>
> > ----- Original Message -----
> > From: <mypearl@dds.nl>
> > To: <vectorlist@vectorlist.org>
> > Sent: Wednesday, June 25, 2003 3:40 PM
> > Subject: VECTOR: Asteroids - getting there...
> >
> >
> > > Hello guys,
> > >
> > > I have een working for many many hours on my Asteroids board since I
> last
> > asked
> > > you guys. I have made some good progress. First, the board was dead,
> > watchdog
> > > resets happening. After replacing one 2114 RAM and all LS157 data
> switches
> > (all
> > > were or went bad) The board played well, even video output, altough it
> was
> > > distorted (jagged X output).
> > >
> > > After replacing one LS374 latch, LS157 selector and analog parts in
> the
> X
> > > counter section, the output is clean... but now the board is caught in
> a
> > loop
> > > and draws the same random vector over and over as can be seen in the
> > following
> > > link:
> > >
> > > http://www.mypearl.dds.nl/Asteroids/Asteroids_large.mpg (1.3MB)
> > >
> > > or
> > >
> > > http://www.mypearl.dds.nl/Asteroids/Asteroids_small.mpg (135 KB)
> > >
> > > As you might be able to see from the screenshot, a lot of sensible
> things
> > are
> > > displayed: Atari copyright notice, Insert coins, the saucer, your
> > spaceship,
> > > the test screen and some moving asteroids (all togheter!).
> > > Depending on the coin DIP switch settings and language the displayed
> > images are
> > > different!
> > >
> > > The weird thing is, in TEST mode EVERYTHING is okay! No RAM/ROM
> errors,
> no
> > > distorted vectors... Just as if there is no problem with the board.
> > >
> > > I have checked all logic signals (even all unnamed TTL inputs and
> outputs)
> > in
> > > the Vector Generator logic (sheet 2A). All signals are alive, except
> > > for '/DMACNT', which is decoded directly from the MPU address bus by
> L6.
> > It is
> > > always high. Replacing L6 does not fix it. Could this explain why I am
> > getting
> > > this? What is the /DMACNT used for?
> > >
> > > I really hope you guys can set me back on the right track... would be
> > eternally
> > > grateful! :)
> > >
> > > Cheers,
> > >
> > > Mendel
> > >
> > >
> >
> >
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> >
>
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>

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Received on Sun Jul 20 09:08:40 2003