Re: omega race hig score save

Did you change the 5101 socket? I'm reaching now. It sounds like you've
really covered everything but there's obviously something missing.

I was thinking about something someone said previously about treating this
5101 like an eeprom when it is in fact a ram. It is addressed, read, and
written on the standard but so "caching" its data in some sort of "main ram"
makes no sense because whenever you want the data, it can be read from its
address inside the 5101 just the same and just as easily as from a 2114.
That said, it makes sense to assume that when you go into your test mode
(without powering down) and you can see your high score there, that it is in
fact being read out of the 5101. If it is writing and reading like that,
then all of the logic chips must be working properly.

That means that this problem falls all the way back to what exactly happens
when the system powers down. Obviously, the data is getting corrupted. It
may have something to do with all of those discrete components that control
the chip select pin (pin 17). I suspect that pin 17 should fall to a
logical low (to disable the chip) before the other pins (such as /wr pin 19,
/batram [CS2] pin 20) fall. If they fall first, the chip will write and
it'll save garbage to who-knows-where since the address and data lines are
dropping like flies. The result would be a chip that contains data with a
bad checksum or CRC and the next time that the game powers up, it would
detect the error and initialize the data space.

Check R150 [1k]. If it is open, this will cause the failure mode that I
just described because it'll drastically raise the voltage at which the
transistors [Q102,103] turn off causing them to stay on too long. Also
check R143 [24k] for an open. Check Q102 [2N4403] and Q103 [2N3904]. If
either one is shorted, this will also cause the same problem because it
keeps the chip enabled after powerdown..

William Boucher
----- Original Message -----
From: "andre" <livnfree_can@yahoo.com>
To: <vectorlist@vectorlist.org>
Sent: Monday, November 03, 2008 9:18 AM
Subject: Re: VECTOR: omega race hig score save

> Actually, I had replaced KJ9 as well.. forgot to write that down..
>
>
> --- On Mon, 11/3/08, William Boucher <boucher@mnsi.net> wrote:
>
>> From: William Boucher <boucher@mnsi.net>
>> Subject: Re: VECTOR: omega race hig score save
>> To: vectorlist@vectorlist.org
>> Date: Monday, November 3, 2008, 8:06 AM
>> JK6 doesn't appear to have anything to do with the 5101
>> problem. You might want to try replacing the 74LS367 buffer
>> at KJ9. It generates /mreq signal. Boy, this one is
>> proving to be a real bear to track down. I wish you lived
>> closer. I could bring over my Tech-Tools Digiview logic
>> analizer and clip it onto the 5101, run the game once and
>> then we'd see exactly was or was not happening.
>>
>>
>> William Boucher
>> ----- Original Message ----- From: "andre"
>> <livnfree_can@yahoo.com>
>> To: <vectorlist@vectorlist.org>
>> Sent: Sunday, November 02, 2008 7:02 PM
>> Subject: Re: VECTOR: omega race hig score save
>>
>
>
>
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Received on Mon Nov 3 19:02:46 2008