Transputer Emulation

One of the architectures I'm interested in are transputers. They are an alternative and dead architecture from the 90s which use parallel mcus to run programs. Each MCU has a serial connection to adjacent MCUs.

I am interested in what can be learned from an alternative parallel architecture, how the language interacts with a different underlying hardware and the potential for modular computing.

Some websites I looked at, there's an overwhelming from a wide range of perspectives, so I haven't looked too closely at anything yet.

https://www.transputer.net - variety of transputer documentation
https://sites.google.com/site/transputeremulator/Home?authuser=0 - transputer emulator
Porting Small-C to transputer and developing my operating system - transputer os

To start with this investigation I want to try to get an emulator up and running. I both got jserver, which is an emulator which can run the T414/T400/T425/T800/T805 type transputers. I also got Oscar Toledo's basic emulator up. Oscar's installation instructions are here: GitHub - nanochess/transputer: Transputer T805 emulator, assembler, Pascal compiler, operating system, and K&R C compiler. The setup for this was very painless on my linux machine, fora revived project from the 90s, it went up immediately. It reminds me of being surprised at how easy it was to work on a DOS CNC machine. I want to return to looking at this, but I want to look a little at the Occam programming language, which is featured in the jserver emulator.

For jserver, I followed the steps here: https://sites.google.com/site/transputeremulator/Home/jserver/installation-instructions?authuser=0. Getting hello world to work was fast. Then I set up the Occam toolset.

Occam is designed for transputers, so it also exposes some of the interesting points of them. Let's look at the hello.occ program.

#INCLUDE "hostio.inc" --  -- contains SP protocol

PROC hello (CHAN OF SP fs, ts )

  #USE "hostio.lib"

  SEQ

    so.write.string.nl    (fs, ts, "Hello world...")

    so.exit           (fs, ts, sps.success)

:

Looking at the Introduction to the Programming Language Occam, I can breakthis down a little bit.

#INCLUDE "hostio.inc" gives us the serial protocols we need, especially those which can write to the output terminal.

A process (PROC ) is the basic element, processes can be, but aren't necessarily concurrent. Processes can only share date through a channel. This means there is no shared variables.

Screenshot 2025-03-31 112448.png

The CHAN type defines a channel. In the main body of the process we use the hostio.lib to write to the serial channel.

Now I slightly more complicated program which computes the square roots.

While getting this running, I edited some of the scripts, essentially just making them use arguments to make building better. The make stage is from the mk.bat script, which is run using mk.bat hello or mk.bat root

imakef %1.btl /o %1.mak

This runs make to create btl and mak files. I also need the emulator description, and entry point defined. This is from the example hello file.

-- hardware description, omitting host connection



VAL k IS 1024 :

VAL m IS k * k :



NODE test.bed.p :  -- declare processor

ARC hostlink :

NETWORK example

  DO

    SET test.bed.p (type, memsize := "T414", 2 * m )

    CONNECT test.bed.p[link][0] TO HOST WITH hostlink



:



-- mapping

NODE application:

MAPPING

  DO

    MAP application ONTO test.bed.p

:



-- software description

#INCLUDE "hostio.inc"

#USE "hello.cah"

CONFIG

  CHAN OF SP fs, ts :

  PLACE fs, ts ON hostlink :

  PLACED PAR

    PROCESSOR application

      hello ( fs, ts )

:

Then the program is built using build.bat

REM Borland make

REM omake -f%1.mak

REM

REM WATCOM wmake

REM wmake -f %1.mak -ms

REM

REM Microsoft nmake

nmake -f %1.

This is just running nmake , everything else is a comment for older oses.

Some notes on getting occam to compile.

All keywords are capitalized
It is very whitespace-sensitive. Indentation seeems to be two spaces. Files need to end on a new-line.

This is a basic sequential program to calculate the square root.

#INCLUDE "hostio.inc" -- contains SP protocol

PROC msqrt (CHAN OF SP keyboard, screen)

  #USE "hostio.lib" -- IO library

  BYTE key,result:

  REAL32 A:

  SEQ

    so.write.string.nl(keyboard, screen, "Value Square Root")

    SEQ i = 1 FOR 10

      SEQ

        so.write.string(keyboard, screen, "i = ")

        so.write.int(keyboard, screen, i, 2)

        A := REAL32 ROUND i

        so.write.real32(keyboard, screen, SQRT(A), 4, 6)

        so.write.nl(keyboard, screen)

    so.exit(keyboard, screen, sps.success)

:

Running:

Booting root transputer...ok

Value Square Root

i =  1    1.000000

i =  2    1.414214

i =  3    1.732051

i =  4    2.000000

i =  5    2.236068

i =  6    2.449490

i =  7    2.645751

i =  8    2.828427

i =  9    3.000000

i = 10    3.162278

Not quite exploiting parallelism yet, but some progress and work into it.

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Transputer Emulation