networked processors f21 and transputer stlye

[Jeff Fox <fox@xxxxxxxxxxxxxxxxxxx>]

Dear MISC readers:

Tim Böscke wrote:
> Sounds like Transputer. This has been tried and is out of fashion 
> now, since it appearantly couldnt live up its promises..

F21 was influenced by the transputer design.  But one must rember
that the transputer was a cpu, memory, and a network interface.
It was targeted mostly for large FP problems where BIG machines
rule. I have also heard most often that the problems were that
it could only be easily interfaced to a small set of (brit) chips 
and made interfacing difficult and expensive.  In this sense it
was about as different from F21 as possible.

F21 is not just for computation but also contains a variety of
I/O hardware to make it operate as an I/O interface as much as
a processor.  In this sense it looks much more like PC, it has
a central processor, memory interface, analog I/O subsystem,
video I/O subsystem, network I/O subsystem, timing and
interupt hardware and parallel port.  In that sense it looks
like a PC but 100x cheaper.

It also looks like some other cheap chips used as much for
specialized I/O processing as computing (except 1000x faster)
The concept is that people need computers with I/O not just 
computing modes.  The model that what the user wants is a cpu 
with I/O subsystems that provide things like audio, video, 
modems, network intefaces etc are what users want.  The Personal 
Computer concept was more sucessful that the transputer. 

F21's network coprocessor was modeled after more modern concepts
like active message passing to get higher efficiency than antiquated
designs.  It has something in common with a transputer but not much.
It has more in common with a PC or workstation which is proven
concept (if only they cost 100 times less).  

The idea of workstation farming is very well proven and very
popular.  The idea of F21 is that you can something very similar
but supports Gordon's Bell's "Don't behead Wordstation" drive.
(The transputer never had a head. Poor little thing. )
You may only need one monitor but you could hang one on each 
node if wanted to and get something more like conventional
network of PCs or workstations.

I worked with the Parallel Processing Connection for a number of
years.  They explored the transputer phenomonon, Linda, PVM,
Scalable Coherent Interface (wow), software to hardware compilers,
different forms of parallel hardware, DSP chips with parallel
communication links on chip, active message passing hardware,
reconfigurable CPU in FPGA, etc. over the years.  Hardware and software
vendors donated equipment and software so that members could
get in depth exposure to the ideas involved.  Many of the things
I learned there (proven sucessful concepts) went into the F21
design. F21 also includes some rather unusual and amazing hardware
that came out of Chuck's imagination, stuff that some people would
love to have access to. 

(Anyway the idea behind F21 was not just make a chip that was
what was fashionable.  There was more involved and trying to be
fashionable was not part of the equation. ;-)

Jeff Fox