🚀 go-pugleaf

There have been a few interesting messages recently on this net on the
question 'where are the workstations?', to which I would ask the question
'do we need a Transputer based workstation?'.

I am on this net and am therefore a strong believer in the Transputer (and
even Occam!) so why am I asking such a question? well I'll attempt to
explain myself.

Multiple Transputer systems are clearly capable of providing a very
impressive processing performance at a very competitive price when
processing certain algorithms. However this does not make them suitable as
the basis of a general purpose computer system, not everything can take
advantage or indeed needs the power of a multiple Transputer system.
Forcing people to port those parts of an application that cannot benefit
from Transputer style parallelism, as well as those parts that can, adds to
the expense/difficulty involved in developing Transputer Applications.

Transputers are good at processing but bad at running a conventional
operating system. This is mainly due to the lack of any support for a
memory management unit, therefore DMA and memory protection are not
possible. This would make it difficult to implement a conventional
workstation, with support for multiple processes (jobs) and multiple users.
Yes I know about Helios! a nice operating system, but I'm not convinced
that it gets around these problems in a safe, consistent and efficient
manner.

The solution (?!!):- use your Transputers in conjunction with an already
existing general purpose computer system. You then only need to port those
parts of an application that can take advantage of the Transputers. Nor do
you need  a complicated operating system or to develop/buy dedicated
peripheral devices such as displays (or less this is the area that your
intending to speed-up by using Transputers!)

The Transputers can then be used either as a co-processor to a host
computer or (much more interestingly) as a 'compute' server on a network.
Unfortunately the standard TDS,  toolkit and other software development
tools do not allow for the flexible co-operation of processes running on
the Transputers with processes on the host. One solution is the CD-TSE
(Cresco Data - Transputer Software Environment) for Transputers hosted in
an Apollo workstation. This allows a program running on the workstation to
initiate processing on the Transputers through a remote procedure call
mechanism and for the two systems to communicate with each other using
communication channels. Trollius and the related Genesys (from Transtech)
operating systems also look interesting in this respect (does anyone know
of any good references on these that are available in the UK?).

I agree with the sentiments expressed by Thomas Donaldson that the
investigation of suitable algorithms for use with the Transputers is
important. The tools needed for software development with Transputers are
well understood algorithm structures not operating systems!. These should
allow efficient software to be easily produced (or at least provide a basis
on which performance of a system can be reasoned about before it is
implemented). If possible such structures should generate software that is
independent of the number of processors and of their interconnection
topology. This will allow the construction of software that can be easily
used on different systems. One structure that has been shown to offer
significant promise in this respect is the 'Processor Farm'.

I am developing a system called ANTS (Aston Networked Transputer System).
This uses a Transputer system hosted by an Apollo DN3000 workstation and
the CD-TSE software. Apollo's Network Computing System (NCS) is used to
allow client programs running on computers on a connected network to make
remote procedure calls to the Transputer system, which then acts as a
compute server to the network. On the Transputer system a modified version
of the processor farm paradigm is used that allows multiple calls to be
processed simultaneously. This is important if the system is to be used as
a true network resource. The penalty paid for this is that the services
provided by the system must be 'trusted', as multiple jobs will be
processed on the same processor. I  have a prototype system working that
demonstrates the potential, efficient - near linear speedup and even
allocation of resources to active calls.

In summary, why not use Transputers for what they are good at; processing -
not providing an operating system (680X0's, 860X86's, Sparcs,
i860's.....etc. are very good at this!). Use Transputers as a component of
a general purpose computing system not as a general purpose computing
system!





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Ian Hardy                                  hardyid@uk.ac.aston.clust 
Dept.Computer Science,                   Tel: 021-359 3611 Ext. 4272 
Aston University, 
Birmingham, B4 7ET
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The above are my own opinions, I don't expect everyone to agree with
them!!.