computer science

TK82C

TK82C 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 TK82C rather than just read about it. In short: TK82C was a Sinclair ZX81 clone made by Microdigital Eletrônica Ltda., a computer company located in Brazil. General information The TK82C had the Zilog Z80A processor running at 3.25 MHz, 2 KB SRAM and 8 KB of EPROM with the BASIC interpreter.

Key takeaways

TK82C 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 TK82C to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TK82C from memory before moving on to harder problems.

Reference excerpt

TK82C was a Sinclair ZX81 clone made by Microdigital Eletrônica Ltda., a computer company located in Brazil.

General information The TK82C had the Zilog Z80A processor running at 3.25 MHz, 2 KB SRAM and 8 KB of EPROM with the BASIC interpreter. The C letter stands for "Científico", or "Scientific" in English. The keyboard was made of layers of conductive (membrane) material and followed the Sinclair layout. The video output was sent via a RF modulator to a TV set tuned at VHF channel 3, and featured black characters on a white background. The maximum resolution was 64 x 44 pixels, based on semigraphic characters useful for games and basic images (see ZX81 character set). The TK82C included the SLOW function, which permitted the video be shown during the processing (the prior version, TK82, a Sinclair ZX80 clone, ran only in fast mode, so the image was not shown during its processing). In reality, the SLOW function was done by an add-on board that was factory-mounted over the main board. Although being a ZX81 clone, the TK82C did not have the ULA chip from Ferranti, used in the former. Instead it was manufactured with a dozen of TTL integrated circuits, which resulted in a somewhat large power consumption. This could be noted as the computer's case used to become quite hot after some minutes of operation.

Data Storage Data storage was done in audio cassette tapes at 300 bits per second, and large programs could take up to 6 minutes to load. Audio cables were supplied with the computer for connection with a regular tape recorder. As the data encoding was entirely done by software, some hacks were made available to allow much faster transfers. Hi-fi recorders were required in order to use the greater speeds with a minimum of reliability.

Accessories A 16 KB DRAM expansion was made available and, despite being optional, became a standard item. Soon after, a 48 KB expansion was also released, but due to pricing and the problematic data storage in cassettes, it never sold well. The TK82C featured a DIN connector for a joystick (in reality, it was wired to the keyboard matrix); Microdigital then marketed an Atari 2600 joystick, accordingly retrofitted to match the DIN connector. A small printer, indeed a ZX Printer clone, was announced for a long time by Microdigital, but was never released.

Compatibility and Legal Issues All software designed to the ZX81 could run in the TK82C with no problems, and vice versa. So it was not uncommon to find software distributed in Brazil, that were nothing more than illegitimate copies of products for the ZX81. However, given the TK82's popularity, a great deal of original software was developed in Brazil as well. In 1983, Sinclair Research sued Microdigital over copyright violation because of the unauthorized cloning of its product. Due to political trends from that time, the Brazilian court in charge of the case sided with Microdigital.

Later Products The TK82C was replaced by the TK83 (it used a ULA similar chip, as the original ZX81) and by the TK85 (a 16 KB RAM version with a case similar to ZX-Spectrum), more robust and with a better design. Microdigital later produced the TK90X and TK95, which were clones of the ZX Spectrum.

Trivia TK82C is also a designation for a copier from Kyocera.

References

External links Microdigital TK82 (archived version)

Illustrations

Worked examples

Example 1 — a first encounter with TK82C

Start with the simplest possible case. Write down what TK82C 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 TK82C 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 TK82C 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 TK82C

In research: TK82C 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 TK82C 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: TK82C is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer-related introductions in 1983, Computer hardware stubs, Computers designed in Brazil, so understanding it makes those chapters shorter.
In everyday life: Look for TK82C 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 TK82C in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TK82C 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 TK82C out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TK82C in simple terms?

TK82C was a Sinclair ZX81 clone made by Microdigital Eletrônica Ltda., a computer company located in Brazil. General information The TK82C had the Zilog Z80A processor running at 3.25 MHz, 2 KB SRAM and 8 KB of EPROM with the BASIC interpreter.

Why does TK82C 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 TK82C?

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 TK82C.