science

SPITBOL

SPITBOL 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 SPITBOL rather than just read about it. In short: SPITBOL (Speedy Implementation of SNOBOL) is a compiled implementation of the SNOBOL4 programming language. Originally targeted for the IBM System/360 and System/370 family of computers, it has now been ported to most major microprocessors including the SPARC.

Key takeaways

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

Reference excerpt

SPITBOL (Speedy Implementation of SNOBOL) is a compiled implementation of the SNOBOL4 programming language. Originally targeted for the IBM System/360 and System/370 family of computers, it has now been ported to most major microprocessors including the SPARC. It was created by Robert Dewar and Ken Belcher, who were then at the Illinois Institute of Technology. Prior to the development of SPITBOL, SNOBOL4 was thought to be slow, memory-intensive, and impossible to compile due to its dynamic nature. While delayed binding prevents everything from being determined at compile time, SPITBOL adopts various strategies for making decisions as early as possible. Recent versions of the SPITBOL compiler are available. Since 2001 the source code for the original SPITBOL 360 compiler has been made available under the GNU General Public License. MACRO SPITBOL is an implementation of SPITBOL written in the 1970s by Robert Dewar and Anthony P. McCann. MACRO SPITBOL is coded in MINIMAL, an assembly language for an abstract machine. The instruction set is carefully defined to allow some latitude in its implementation, so that hardware operations favorable to string processing can be exploited. An implementation of MINIMAL that was designed for interpretation on microcomputers was done by translating MINIMAL into MICRAL using a translator that was itself implemented in SPITBOL. The MICRAL version of MACRO SPITBOL, together with the MICRAL interpreter ran in under 40K bytes. This extreme object code compression of MICRAL is achieved using a set of machine code macro substitutions that minimizes the space required for the object code and macro table. The complexity of known algorithms for an optimal solution to this problem are high, but efficient heuristics attain near-optimal results. The source code for MACRO SPITBOL was released under the GNU General Public License on April 17, 2009.

References

Worked examples

Example 1 — a first encounter with SPITBOL

Start with the simplest possible case. Write down what SPITBOL 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 SPITBOL 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 SPITBOL 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 SPITBOL

In research: SPITBOL 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 SPITBOL 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: SPITBOL is common in secondary-school and first-year university syllabi. It links to neighbouring topics Compilers, Pattern matching programming languages, SNOBOL programming language family, so understanding it makes those chapters shorter.
In everyday life: Look for SPITBOL 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 SPITBOL in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SPITBOL 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 SPITBOL out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SPITBOL in simple terms?

Why does SPITBOL 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 SPITBOL?

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 SPITBOL.