Dont shut off your machines when....

Fly

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when it's on the screen to enter your initials. I lost my all time scores on Return of the Jedi.

My top ten scores ranged from 1.7 mil to 2.1 mil. I had a decent game going and I was exiting the Death Star and doing the math in my head for how many more times I had to do it to get 2 mil and accidentally finished the game. The trick to this game is to NOT finish and do the level over again for more points and I was at 1.75 mil with a few men left and headed to an easy 2 mil but ended with 1.85 mil on accident and shut the machine off on the name entry screen.

That's all it took. Poof! All gone.

Any other games with this issue?

Hector
 
Very interesting!

When digging into a problem with my Atari Star Wars high score (and general nvram issue), I discovered that Star Wars (and other games) are designed to automatically write to nvram when you power off the game. In the case of Star Wars a x2212 chip is used and this chip has both RAM and nvram. This means the game writes all the persistent info to the chip and it is stored in RAM. However, when a specific signal is given to the chip it will copy the RAM into its internal nvram.

This process that triggers the copy from ram to nvram isn't completely under software control. When the hardware realizes the regulated and unregulated voltage gets off, it assumes the power has been turned off and it triggers the nvram to "store". There is a capacitor that holds enough energy to ensure the chip can complete this operation even with the power off.

With all that background, my guess is that your game starts writing to the RAM portion of the nvram chip when the hi score screen is displayed. However, it doesn't update the checksum/crc until you enter all your initials. This means if you power off your game during this point, the data is stored automatically by the hardware but it doesn't have a valid checksum/crc. At next boot the game reads the data, performs validation, and it fails. So it goes back to defaults.

That's just my guess.

... Altan
 
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