[Hardware] language neutral processors

Hans-Martin Mosner hmm at heeg.de
Thu Aug 2 06:29:54 UTC 2007

Jecel Assumpcao Jr schrieb:
> I am back from a nice vacation (my first since 1982...) and see that you
> have all been waiting patiently for me to return before starting any
> interesting discussions ;-)
Ok, now that you're back, I can finally ask the questions which have
puzzled me ever since :-)
When implementing Smalltalk hardware, what kind of object memory design
would you prefer:
- object table vs. direct pointer
- ref counting vs. generation scavenging cs -whatever-
- page-based virtual memory vs. object-based VM vs. none at all
- in-band tags vs. out-of-band tags
Let me explain the last one. Smalltalk Implementations have typically
had in-bad tags, i.e. the tags have only meaning in a word which is
known to be an oop. The Burroughs machines had out-of-band tags, that
is, every memory word had an additional tag. That way, you could even
know whether a memory word contained uninterpreted bytes, a float value,
or an "oop" (descriptor).

> One interesting side effect of this trip is that I now have a new FPGA
> development kit - the ML401 from Xilinx. 
Just out of curiosity: how much does one pay for such a kit? I don't
know whether my wife would approve of a major investment into something
of little perceived value :-)


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