science

ICL Direct Machine Environment

ICL Direct Machine Environment is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand ICL Direct Machine Environment rather than just read about it. In short: Direct Machine Environment, abbreviated DME, was a mainframe environment for microcode based versions of the ICL 2900 Series (2960 and the second-generation S-Series) of computing systems from International Computers Limited that was developed in the 1970s. DME was more-or-less an ICL 1900 order code processor in microcode, which permitted the ICL 1900 series executive, operating systems and program libraries to ope…

Key takeaways

ICL Direct Machine Environment belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect ICL Direct Machine Environment to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of ICL Direct Machine Environment from memory before moving on to harder problems.

Reference excerpt

Direct Machine Environment, abbreviated DME, was a mainframe environment for microcode based versions of the ICL 2900 Series (2960 and the second-generation S-Series) of computing systems from International Computers Limited that was developed in the 1970s. DME was more-or-less an ICL 1900 order code processor in microcode, which permitted the ICL 1900 series executive, operating systems and program libraries to operate on the ICL 2900 series. The ICL 2905 was a rebrand of the ICL 2950 that only ran DME/2, the second version of DME, introduced for marketing reasons.

Reason for Development At this time most companies that had computers had large teams of programmers to write their applications. DME was developed so that customers could buy the new hardware and run their 1900 or System 4 applications whilst they developed their replacement VME applications. This led to some users running DME and VME alternately on the same machine for some years. Unfortunately this led to situations where development teams were waiting around for time to run their new applications. This, and the fact that some users were not moving to the new system, led ICL to develop a system called Concurrent Machine Environment (CME) under which VME ran DME as a subsystem, enabling 1900 and System 4 applications to be run on a 2900 or Series 39 machine alongside VME applications.

References

Worked examples

Example 1 — a first encounter with ICL Direct Machine Environment

Start with the simplest possible case. Write down what ICL Direct Machine Environment claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to ICL Direct Machine Environment before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about ICL Direct Machine Environment ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of ICL Direct Machine Environment

In research: ICL Direct Machine Environment appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses ICL Direct Machine Environment in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: ICL Direct Machine Environment is common in secondary-school and first-year university syllabi. It links to neighbouring topics ICL operating systems, Operating system stubs, so understanding it makes those chapters shorter.
In everyday life: Look for ICL Direct Machine Environment outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study ICL Direct Machine Environment in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what ICL Direct Machine Environment means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain ICL Direct Machine Environment out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is ICL Direct Machine Environment in simple terms?

Why does ICL Direct Machine Environment matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study ICL Direct Machine Environment?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on ICL Direct Machine Environment.