Implementation on Digital PDP-8


Hardware platform Digital PDP-8
Operating system Standalone
Author John Forecast
Implementation method LOWL-map
ML/I version AIC
Implementation version Unknown


This implementation was performed at the University of Lancaster by John Forecast, an undergraduate student. He took the implementation to the University of Essex when he became a postgraduate there, and someone unknown carried out the modifications so that it could run in three fields as well as two (see below).

This was a challenging implementation, being largely hand-mapped due to severe hardware constraints. The PDP-8 was a word based machine with 12 bit words, and direct instruction addressability of only 128 words. Indirect addresses were limited to 4096 words, each 4096 word area being known as a field. Two versions could be built; one for a two field machine (code in one field, ML/I stacks in the other), and one for a three field machine (code in one field, and the two ML/I stacks each occupying one of the other two fields).

Available files

This section includes not only program files, but also supporting files such as test suites, etc. The source code of this implementation has survived.

An image of the ML/I executable paper tape has been built by Bob Eager, and is also available. This is the three field version.

File format

Each file, or group of files, is available as a ZIP file (.ZIP). This can be unpacked using the ZIP utility, which is freely available from Clicking on the 'Zip' graphic at the end of this section will take you straight to the main UnZip page.

File downloads

Title Download
ML/I executable file
PAL-8 source file
ML/I test suite

Available user documentation

Documentation format

Each document is available in Portable Document Format (PDF). This can be viewed on most systems using appropriate software such as Adobe Acrobat Reader, which is freely available from Clicking on the 'Get Adobe Reader' graphic at the end of this page will take you straight to the main Adobe Acrobat Reader page.

As an alternative, each document is also available in HTML, as a single file. This can of course be viewed with any browser, although the output is not as pleasing as the PDF version.

Document downloads

These are the currently available user documents which are relevant to this particular implementation:

Title Download
An ML/I tutorial
A simple introductory guide to ML/I
ML/I User's Manual
Appendix M to ML/I User's Manual

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Last updated: 11 Oct 2018