Re: a dozen cpu's on a chip

On May 14, 7:53 pm, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Wed, 14 May 2008 18:54:01 -0700 (PDT), MooseFET



<kensm...@xxxxxxxxx> wrote:
On May 14, 12:27 pm, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
[....]
have written a small multitasker (is not that what we all did set out to do once ;-) ),

Three, actually. One for the 6800, one for the PDP-11, one for the
LSI-11. All were pre-emptive multitaskers with rather general i/o
architectures.

I'll jump in here to say that I've written one for the 8051 and one
for a PDP-8.

The PDP-8 one was many years back. The PDP-8 doesn't know what a push
or pop or even a call or return is. This made it require a lot of
strange rules be applied to the tasks.

The 8 was sort of a dog; it probably ruined the minds of a generation
of programmers. Rick Merrill wrote the FOCAL language interpreter for
it, a complete editor, user program buffer, runtime system, floating
point, formatted print, all that in 4k 12-bit words. He synthesized a
lot of "modern" stack constructs to work arould the 8's klunkiness.
I've met Rick, very nice guy.

The 8 used no more transistors than absolutely needed. It was for
quite a while, the most common computer in the world. I always use
the CDP1802 as the low end for my comparisons so I say that the PDP-8
was a nice machine.

[....]
What you need is multiple processors!

In a lot of cases a fast serial bus linking multiple chips would be
good. The keyboard has a lot of leads on it. It would be nice to
reduce it to only two signals.



John

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