Python bytecode compatibility between interpreter versions

[Terry Reedy]

"Jon Perez" <jbperez808 at yahoo.com> wrote in message
news:c3gqvu$27bujr$1 at ID-180326.news.uni-berlin.de...
> The answers also make me curious about how CPython's VM works.
> I suppose that, unlike Java, it is constantly being reworked
> in more extensive ways from one dot-version to another.  Would
> that also explain why there is no detailed spec detailing how
> CPython's VM works (since its design is not as nailed down as,
> say, the JVM)?

The CPython VM is intentionally underdocumented and intentionally not part
of the language spec.  It is still being developed and might radically
change in the future.  There will probably be minor changes in the next
release as a result of experiments designed to find combinations of codes
that dependably run faster on all major platforms.  However, the current
byte code is described in the Library Ref as part of the doc for the dis
(assembly) module.

Terry J. Reedy