Re: omega race hig score save

I was looking at the schematic tonight just out of curiosity, even though I
don't have the game myself.

I found a datasheet for the 5101. Most of what I've been reading on some
sites is that 3.6V at pin 22 really isn't quite enough to keep it up. That
datasheet however specifies that 2V is enough to hold data. Apparently,
4.8V will not hurt the thing, since it runs on 5V anyway when the game is
on, so maybe you could simply try 4 cells. That would explain why both
boards failed to hold the data when off. According to the datasheet, 4
cells is overkill.

It looks like the 5101 is enabled by a lot of things, one being that crazy
over-complicated transistor circuit (Q102 & Q103) which looks like it's only
there to tell the 5101 when the main power is on or off (via pin 17 chip
select or CS2). If the pin 17 signal fails to come up, the 5101 will not
enable writes to it so your hi-score would not be saved.

Another is the pin 19 (active low "batram" which is chip select CS1) signal
coming from the 74138 at location PN2. Then there's all the chips that
enable the 74138 such as the 7404 inverters at S6 & PR1, and the nand gate
at P4. A fault in any of these 4 chips would prevent the batram signal from
being generated.

Another is the pin 20 (active low write) signal. Is that being generated?
If it is stuck high, it can't write. If pin 18 (called RD but is actually
output disable) is stuck high, the data can't get out onto the bus and so
the game can't read it.

William Boucher
----- Original Message -----
From: "andre" <livnfree_can@yahoo.com>
To: <vectorlist@vectorlist.org>
Sent: Thursday, October 30, 2008 7:48 PM
Subject: VECTOR: omega race hig score save

>I have a couple boardsets I added battery packs to. I replaced the 5101 on
>both as well. The battery packs are 3 x 1.2v for 3.6v as I believe that is
>what the original single battery was rated at. But neither board saves the
>high score still. I measure 3.5v on the 5101 with the machine turned off,
>but it still restarts with the 'AE' generic highscore and not any other one
>I get. Any ideas why its not working? The 5101 in the sockets were also
>both checked for continuity and passed.
>
>
>
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Received on Fri Oct 31 00:39:06 2008