RE: Tempest - Vector Generator RAM

Wooohooo! I found it. It was one of those pesky traces. I had recently
replaced the 245 (F2) and thought I had confirmed the continuity between it
and the other 245 (H2), but alas, I must have missed one of the pins... man
o man.. always the one you haven't tested.

Anyway, thanks to Chris for the suggestion.

Now of course, I am back to fixing my original problem of wiggley vector
characters.. I have replaced half of the board with sockets just trying to
find the culprit AND I have been doing it non-randomly (ie. tracking back
from the video section to what I thought made sense). Alas, I have yet to
come up with a solution.....

Pluggin away...
Andy

*I think I can, I think I can, I think I can... *

-----Original Message-----
From: Chris Loggans [mailto:chris.loggans@deltasolutions.com]
Sent: November 27, 2000 11:59
To: 'Evrovski, Andrew '
Subject: RE: VECTOR: Tempest - Vector Generator RAM

Andrew,

    All of the lines that go to the mathbox board have buffers on them to
separate them from the main buss. I'd check those buffers (should be
74LS245's or similar 20 pin chips).

Good luck,
-Chris

-----Original Message-----
From: Evrovski, Andrew
To: 'vectorlist@synthcom.com'
Sent: 11/27/00 10:00 AM
Subject: RE: VECTOR: Tempest - Vector Generator RAM

Well, I got this working.  However, my board comes back up and the text
shows up on the game, but all the gameplay vector graphics are all
screwed up. (ie. maze doesn't draw or showup and the enemies and my
player (whatever I am) blinks and appears once in awhile and I can see
the other things off and on).  All the while the score displays and all
other things not to do with gameplay show up.
 
Also, I go to the test screen and it all is fine (including all the
cross-hatches, scaling mathbox etc).  However, I do have a "M" for
mathbox in the text screen (I interchanged the back smaller board with
one that is known working and the "M" and vector problem still shows
up.  I checked the connector and performed continuity tests across the
connecter pins once connected and they all checked out).
 
Any ideas?
 
A>

-----Original Message-----
From: Evrovski, Andrew [mailto:andy@cyberplex.com]
Sent: November 24, 2000 11:10
To: vectorlist@synthcom.com
Subject: VECTOR: Tempest - Vector Generator RAM

Folks,

        I have a problem with my Vector Gen RAM.  I have socketted the
RAM and when booting up in test mode, I get a problem with RAM M3.  I
replace this with a known working good 2114 and it still shows up as
such (4 short beeps and then 1 long beep).  I conduct some continuity
tests and according to the schematic, I see connections between all
appropriate pins on the RAM, but I can see there is a problem with some
of the RAM connections, but I don't know what to do about it.  What I
mean is that on the schematic, pins 11-14 on RAMs J3,K3,L3,M3 are
DVG3,DVG2,DVG1,DVG0 and J4,K4,L4,M4 are DVG7,DVG6,DVG5,DVG4 and these
behave differently than the address lines.  All the address lines are
tied together on the RAMS, but the 11-14 are tied together in BANKS (the
3's are together and the 4's are together) but they are both tied to
I/04, i/03, I/02, I/01.  Here is the problem.... what the HECK is I/0?  
Where are these connected?  I measure impedance across pins 11-11,
12-12,13-13,14-14 across that I/0? barrier (across the 3's to 4's) and I
get 19K 11-11, 13-13, 14-14, but on pins 12-12, it is an open circuit. 
I measure a known good working board and the impedance across all of the
pins above is the same (for all 4 pins INCLUDING pin 12) so I know that
there is something wrong with the connections on that pin, but until I
know *where* the connection is supposed to go, I will not know how to
fix it.

        Can anyone shed some light on what the I/0? connections are
referring to?

Much appreciated.

Andrew Evrovski
HPC Development Director
Cyberplex
t: 902.429.4721 ext.109
f: 902.423.0899
www.cyberplex.com

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Received on Thu Nov 30 20:21:12 2000