computer science

List of 8-bit computer hardware graphics

List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics rather than just read about it. In short: This is a list of 8-bit computer color palettes, and graphics, which were primarily manufactured from 1975 to 1985. Although some of them use RGB palettes, more commonly they have palettes of 4, 16, or more colors that are neither bitwise nor intensity-level combinations of the RGB primaries, but instead consist of fixed colors defined by ROM or dedicated circuitry and selected by the manufacturer.

Key takeaways

List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of List of 8-bit computer hardware graphics from memory before moving on to harder problems.

Reference excerpt

This is a list of 8-bit computer color palettes, and graphics, which were primarily manufactured from 1975 to 1985. Although some of them use RGB palettes, more commonly they have palettes of 4, 16, or more colors that are neither bitwise nor intensity-level combinations of the RGB primaries, but instead consist of fixed colors defined by ROM or dedicated circuitry and selected by the manufacturer. Due to mixed-bit architectures, classifying these systems solely by their "n-bit" designation is not always precise. Another error is assuming that a computer's color palette represents what it can show all at once. Resolution is also a crucial aspect when criticizing an 8-bit computer, as many offer different modes with different amounts of colors on screen, and different resolutions, with the intent of trading off resolution for color, and vice versa.

3-bit RGB palettes Systems with a 3-bit RGB palette use 1 bit for each of the red, green and blue color components. That is, each component is either "on" or "off" with no intermediate states. This results in an 8-color palette ((21)3 = 23 = 8) that have black, white, the three RGB primary colors red, green and blue and their correspondent complementary colors cyan, magenta and yellow as follows:

The color indices vary between implementations; therefore, index numbers are not given. A common selection has 3 bits (from LSB to MSB) directly representing the 'Red', 'Green' and 'Blue' (RGB) components in a number from 0 to 7. An alternate arrangement uses the bit order 'Blue', 'Red', 'Green' (BRG), such that the resultant palette - in numerical order - represents an increasing level of intensity on a monochrome display. The 3-bit RGB palette is used by:

The ECMA-48 standard for text terminals (sometimes known as the "ANSI standard", although ANSI X3.64 does not define colors) Teletext Level 1/1.5 Teletext. Videotex Oric computers BBC Micro The original NEC PC-8801 up to the MkII The original NEC PC-9801 with original 8086 CPU before the VM/VX models All Sharp X1 models before the X1 Turbo Z The Sharp MZ 700 Fujitsu FM-7, FM New 7, FM 77 before the FM77AV Sinclair QL The Macintosh SE with a color printer or external monitor The SECAM version of the Atari 2600 The Color Maximite, a PIC32 based microcomputer The Thomson TO7 (with spatial constraints – only 2 colors for each group of 8×1 pixels) The Matra Alice 32 and 90 The Philips VG5000 Specific details about implementation and actual graphical capabilities of specific systems, are listed on the next sub-sections.

World System Teletext Level 1

World System Teletext Level 1 (1976) uses a 3-bit RGB, 8-color palette. Teletext has 40×25 characters per page of which the first row is reserved for a page header. Every character cell has a background color and a text color. These attributes along with others are set through control codes which each occupy one character position. Graphics characters consisting of 2×3 cells can used following a graphics color attribute. Up to a maximum of 72×69 blocky pixels can be used on a page.

Simulated image

BBC Micro BBC Micro has 8 display modes, with resolutions like 640×256 (max. 2 colors), 320×256 (max. 4 colors) and 160×256 (max. 16 logical colors). No display modes have cell attribute clashes. The palette available has only 8 physical colors, plus a further 8 flashing colors (each being one of the eight non-flashing colors alternating with its physical complement every second), and the display modes can have 16, 4 or 2 simultaneous colors.

Simulated image

BBC Micro display modes

Sinclair QL (Sinclair Quantum Leap)

On the Sinclair QL two video modes were available, 256×256 pixels with 8 RGB colors and per-pixel flashing, or 512×256 pixels with four colors: black, red, green and white. The supported colors could be stippled in 2×2 blocks to simulate up to 256 colors, an effect which did not copy reliably on a TV, especially over an RF connection. Pixel aspect ratio was not square, with resulting image proportions close to 4.4:3, making the image extend into the horizontal overscan area of a CRT TV.

PC-8000 series The NEC PC-8000 was capable of displaying graphics with a resolution of 160x100 pixels and 8 colors.

4-bit RGBI palettes

The 4-bit RGBI palette is similar to the 3-bit RGB palette but adds one bit for intensity. It contains variants of colors (dark or bright on most machines, but saturated or unsaturated was also possible) potentially giving a total of 23×2 = 16 colors. Some implementations had only 15 effective colors due to the "dark" and "bright" variations of black being displayed identically. Others generated a grey tone or a different color. This 4-bit RGBI schema is used in several platforms with variations, so the table given below is a simple reference for the palette richness, and not an actual implemented palette. For this reason, no numbers are assigned to each color, and color order is arbitrary.

Systems that used this palette scheme:

IBM's original Color Graphics Adapter IBM's Enhanced Graphics Adapter, in CGA modes Tandy graphics on IBM's PCjr and Tandy 1000-series computers Plantronics Colorplus on a limited number of PC-compatible computers MCGA and VGA graphics standards for backward compatibility Commodore 128 series for its 80-column mode ZX Spectrum (and compatible) (with spatial constraints – only 2 colours for each group of 8x8 pixels) CPC 464/664/6128 Sharp MZ-800 series computers Thomson MO5 and TO7 (with spatial constraints – only 2 colours for each group of 8x1 pixels) Specific details about implementation and actual graphical capabilities of specific systems, are listed on the next sub-sections.

ZX Spectrum

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Illustrations

List of 8-bit computer hardware graphics illustration

Worked examples

Example 1 — a first encounter with List of 8-bit computer hardware graphics

Start with the simplest possible case. Write down what List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics

In research: List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics 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: List of 8-bit computer hardware graphics is common in secondary-school and first-year university syllabi. It links to neighbouring topics Color depths, Computer graphics, Computer output devices, so understanding it makes those chapters shorter.
In everyday life: Look for List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is List of 8-bit computer hardware graphics in simple terms?

Why does List of 8-bit computer hardware graphics 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 List of 8-bit computer hardware graphics?

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 List of 8-bit computer hardware graphics.