LastXY Register for WP34S

[Bit]

(12-01-2014 05:10 PM)brouhaha Wrote:  

(11-30-2014 09:31 PM)Marcus von Cube Wrote:  The 31S has an undo feature which restores the complete working memory to the state it had before the last operation. This is only possible because the working memory of the 31S is way below the 2K RAM we have available. Implementing such a feature is just impossible on the 34S.

The undo save could be in the non-battery-backed 4K of RAM. If you turn the 34S off, or leave it idle so it turns itself off, then undo would not be available when you turn it back on.

Of course, there might not be enough Flash space left to implment that. I don't think there are many features that I'd be happy to dump in favor of adding undo.

Unfortunately the content of that 4K RAM is usually lost between keystrokes as the device goes to sleep to save power. There's very little memory left to play with. Perhaps you could reduce the number of general purpose registers to make space for some undo feature.