🚀 go-pugleaf

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The transputer is built to support, right in the _microcode_, multiple
processes per CPU, and interprocess communication both inside the same
CPU and between neighboring CPUs.  The _hardware_ takes care of time-slicing
between low-priority (user) processes, synchronizing communicating
processes, preempting low-priority processes for high-priority wake-ups
(e.g. a message sent to a system process), etc.  And all with _very_
low overhead.

I agree that limiting the number of concurrent
processes to the number of CPUs (currently low, say 4 for a starter
machine --- wish I had such a starter now...) is not a viable solution.
And I agree that an MMU would be nice.  BUT: many people multitask on
one lousy 68000 (e.g., Amiga (shish!) or even the ST w/RTX).  The main
problem, as I see it, is that if one process, say the program you are
developing, bombs, the whole system goes down.  That's where 4 transputers
w/1Meg each are good enough: 1 for you DA's, one for your compiler system,
1 for your background uploads, and still one left for your crash-prone
experimental program.  If the latter crashes, you reboot just that one
transputer.

Helios is NOT Unix.  Unix is NOT designed for a multiprocessor personal
machine, either.  To quote a Helios document (by N.H. Garnett, Perihelion
Software):

	"That the transputer is in need of an operating system is self
	evident...  Most existing microprocessor OS's cannot support
	multi-processor hardware, even where they support multi-tasking.
	Unix is too large, its model of processes does not correspond
	to that of the transputer, and it remains essentially a uni-
	processor OS..."

Helios is supposed to be a general OS for a network of transputers,
not just for the ABAQ.  Whether they did a good job of it, and whether
it will take off, I have no idea.  I wish somebody else was marketing
it rather than uncle Jack...

- Moshe Braner

PS: still looking for a used 520ST system.