Timothy Rowledge <tim at sumeru.stanford.edu> wrote:
> > How old are the oldest bits in Squeak?  When was the last time an image
> > was created from scratch, as opposed to being modified from a previous
> > version?
> 
> Well that's two quite separate questions. I'm pretty sure the answer to 
> the first one is likely to be 'from about 1978' since my assumption is 
> that st-80 image 1 was cloned from a st-78 image. Whether that was in 
> turn cloned from a 76 or even eventually a 72 I couldn't say - but I 
> bet Dan or Ted could.
> 
> The last time an image was made from scratch could be more recent than 
> you'd expect. Ale. is/was doing work with a system that can do that. 
> He's mentioned it a few times on the list.


True.  I will count a clone as preserving the bits, so long as the most
it does is rearrange some header formats without changing the data. 
After all, if you take a hard line on this, then you have to consider
loading and saving an image to be generating a new version, which is
kinda silly.

And furthermore, the real issue for me is not the "bits" part but the
continuous modification (and branching) of a running program.  Even a
complete rearrangement of the lew-level format does not constitute
restarting the program from scratch.  When the program restarts it will
just feel a little different than before, but it will continue at the
same point it left off.

It sounds like 1977 is a good year to go with.  Jecel, the green book
citation you found is excellent.  Thanks everyone!


-Lex