computer science

P112

P112 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 P112 rather than just read about it. In short: The P112 is a stand-alone 8-bit CPU board. Typically running CP/M or a similar operating system, it provides a Z80182 (Z80 upgrade) CPU with up to 1MB of SRAM memory, 32KB of in-system programmable flash ROM, serial, parallel and diskette I/O, and a real-time clock, in a 3.5-inch drive form factor.

Key takeaways

P112 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 P112 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of P112 from memory before moving on to harder problems.

Reference excerpt

The P112 is a stand-alone 8-bit CPU board. Typically running CP/M or a similar operating system, it provides a Z80182 (Z80 upgrade) CPU with up to 1MB of SRAM memory, 32KB of in-system programmable flash ROM, serial, parallel and diskette I/O, and a real-time clock, in a 3.5-inch drive form factor. Powered solely from 5V, it draws 150mA (nominal: not including disk drives) with a 16 MHz CPU clock. Clock speeds up to 24.576 MHz are possible. The P112 is notable because it was the first of the hobbyist single-board computers to reach the production stage. The P112 hobbyist computers were relatively widespread and inspired other hobbyist centered home brew computing projects such as N8VEM home brew computing project. The P112 project still maintains many devoted enthusiasts and has an online repository of software and other information. The P112 computer originated as a commercial product of "D-X Designs Pty Ltd" of Australia in 1996. As of August 2016, Dave Brooks has released the hardware and software components of P112 into the public domain, under the GPL. The PCB layout is available in the original Protel format, and translated into the current Altium Designer 16 format, which many PCB fabricators can accept. The P112 board was last available new in 1996 by Dave Brooks. In late 2004 on the Usenet newsgroup comp.os.cpm, talk about making another run of P112 boards was discussed. David Griffith decided to produce additional P112 kits with Dave Brooks' blessing and the assistance of others. In addition Terry Gulczynski makes additional P112 derivative hobbyist home brew computers. Hal Bower was very active in the mid-1990s on the P112 project and the commercial "Banked/Portable BIOS" CP/M-compatible operating system was sold for the P112 between 1992 and 1999. It has now been released as open source under the GPL license.

References

Worked examples

Example 1 — a first encounter with P112

Start with the simplest possible case. Write down what P112 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 P112 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 P112 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 P112

In research: P112 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 P112 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: P112 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Single-board computers, so understanding it makes those chapters shorter.
In everyday life: Look for P112 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 P112 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what P112 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 P112 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is P112 in simple terms?

Why does P112 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 P112?

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 P112.