On Jan 11, 2007, at 4:37 PM, David Boyes wrote:
Just for my curiousity. Was CP-67 the first "virtualization engine"
ever
produced? Or did some other company have this type of ability before
IBM
did it?
See Melinda Varian's "VM: Past Present and Future" paper for all the
gory details from the IBM perspective.
There were efforts at DEC with the PDP-8 OS-8 system to do some device
virtualization, but not the true simulation of CP. Probably the next
really serious virtual machine implementation was the p-System at
UCSD.
Interestingly, the first virtual machine implementation for
microcomputers was *not* the p-System, but Infocom's Z-Machine, which
they used to fit the Great Underground Empire into 48K. This is also
how Infocom was able to support such a wide variety of systems in the
magnificently diverse landscape that was the 8-bit mico era.
zcode is still the native target of the Inform programming language,
which is probably the most popular text adventure development
platform extant. It has been extended with a virtual machine known
as glulx, which is pretty much just like zcode but with the IO handed
off to another layer (glk) and the 16-bitness removed, with the
overall effect that you have 4G rather than 128K of memory to squeeze
your game into. (later z-machine versions raised the bar to 256K
(v5,6) during Infocom's lifetime, and the text adventure community
has developed a z8 format allowing 512K (no one uses v7))
Adam
