computer science

IBM System/370 Model 115

IBM System/370 Model 115 is a computer 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 IBM System/370 Model 115 rather than just read about it. In short: The IBM System/370 Model 115 was announced March 13, 1973, at that time the low-end model of the System/370 line. It was promoted as "an ideal System/370 entry system for users of IBM's System/3, 1130 computing system and System/360 Models 20, 22 and 25." The Model 115 was withdrawn on March 9, 1981.

Key takeaways

IBM System/370 Model 115 belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IBM System/370 Model 115 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IBM System/370 Model 115 from memory before moving on to harder problems.

Reference excerpt

The IBM System/370 Model 115 was announced March 13, 1973, at that time the low-end model of the System/370 line. It was promoted as "an ideal System/370 entry system for users of IBM's System/3, 1130 computing system and System/360 Models 20, 22 and 25." The Model 115 was withdrawn on March 9, 1981.

Specifications The CPU had a CPU and memory cycle time of 480 ns. Main memory was composed of MOSFET monolithic integrated circuits. The Model 115 came standard with 65,536 (64 KB) of memory, but it could optionally be ordered with up to 196,608 (192 KB). The system had a CRT operator console. Standard features of the Model 115 were the System/370 standard and commercial (including decimal arithmetic) instruction sets, and a "direct disk attachment" for IBM 3340 disk drives. Optional features included System/370 floating point instructions, System/360 Model 20 compatibility, IBM 1401, 1440 and 1460 compatibility, and various input/output attachment options (see below).

Input/output The Model 115 used integrated attachments to connect to I/O devices. The standard direct disk attachment could attach two to four IBM 3340 disk drives for a total of up to 280 million bytes. Optional integrated attachments provided a standard multiplexer channel interface for slow-speed devices, or, alternatively, an "integrated card I/O attachment" for attachment of either an IBM 5425 Multifunction Card Unit or an IBM 2560 Multifunction Card Machine. An "Integrated Printer Attachment" allowed attachment of either an IBM 3203 or an IBM 5203 line printer. A "magnetic tape adapter" supported an IBM 3210/3211 controller and tape drives. An "Integrated Communications Adapter" could attach up to "four synchronous and eight asynchronous communications lines, or as many as five synchronous communications lines"

Software The operating system for the Model 115 was either DOS/360 or DOS/VS. DOS/VS supported a single address space of 16,777,216 (16 MB) of virtual storage. This address space could be divided up into up to five partitions. The system could run all software written for System/370 (as long as memory and device requirements were met) Language processors included Assembler, APL, RPG II, COBOL, FORTRAN and PL/I.

References

Illustrations

Worked examples

Example 1 — a first encounter with IBM System/370 Model 115

Start with the simplest possible case. Write down what IBM System/370 Model 115 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer 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 IBM System/370 Model 115 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 IBM System/370 Model 115 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 IBM System/370 Model 115

In research: IBM System/370 Model 115 appears in computer 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 IBM System/370 Model 115 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: IBM System/370 Model 115 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer-related introductions in 1973, Computer hardware stubs, IBM System/360 mainframe line, so understanding it makes those chapters shorter.
In everyday life: Look for IBM System/370 Model 115 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study IBM System/370 Model 115 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what IBM System/370 Model 115 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 IBM System/370 Model 115 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IBM System/370 Model 115 in simple terms?

Why does IBM System/370 Model 115 matter?

Because it connects several computer 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 IBM System/370 Model 115?

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 IBM System/370 Model 115.