[Vm-dev] Primitive table support for running older images

[Jecel Assumpcao Jr.]

Bert Freudenberg wrote on Thu, 22 Dec 2016 16:40:51 +0100
> In SqueakJS I have a single flag oldPrims to switch between two set of primitives.
> This appears to work fine all the way back to Squeak 1.x. The flag is set based on
> whether the image format has closures or not.

I had the impression, based on some difficulties on getting the
simulator to work (around 2008, I think), that at one point an instance
variable in a key class (Process, most likely) stopped being used and
then a few versions later it got reused in a different way. This also
happened to a numbered primitive or two. And the version number stayed
6502 though all these changes. So a newer VM would appear to run an
older image just fine but once in a while you got a really strange
crash.

My hope is that this was just some horrible nightmare of mine and not
actual memories, but I will have to take some time searching through old
email messages to be sure.

-- Jecel