63 votes

Why didn't early color TV sets accept RGB input?

When colour television broadcasts began (1960s, in the UK; perhaps a little earlier in North America?) there weren't any local devices that customers might want to use. Broadcast TV was the only ...
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  • 1,388
57 votes
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Why were animated screensavers used instead of a black screen on CRT monitors?

To elaborate on Jon Custer's comment: yes, for protecting the display against burn-in, a black screen would do just as well or better as any "screensaver". However, the graphical effects ...
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43 votes

Why did 80x25 become the text monitor standard?

Where did the 80x25 text terminal size come from? Quick answer: It's one Punch Card Per Line Resulting in 24/25 lines (cards) per screen when using a 4:3 tube and a reasonable font as dictated by ...
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  • 173k
37 votes

Why did some video games apparently use "interlaced" video modes?

Indeed, early devices such as C64, NES, or IBM PC with CGA adapter did not use interlacing, but simply sent 240p to the TV. And later devices such as the Amiga could send either 480i or 240p. But TVs ...
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  • 17.9k
37 votes

Why were animated screensavers used instead of a black screen on CRT monitors?

A blank screen would have been just as effective for protecting the CRT from the burn-in associated with a static display. However, for a time in the late 80's through 1990's, certain popular ...
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  • 57.3k
32 votes
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Square pixels and TV output

CRT TVs are analog devices, there is no "pixel", but the size of the spot limits the resolution of the image, as the size of silver nitrate crystals limits the resolution of photo films. Several ...
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  • 1,446
27 votes

Is it possible to swap the Apple IIc's monochrome CRT tube for a color one?

If you don't know, then the answer is "no". It certainly is possible to get a color CRT tube and matching electronics and fit them into a cleared out case. However, if you have to ask people on the ...
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  • 295
26 votes
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Why did 80x25 become the text monitor standard?

A lot of early PCs and terminals were designed to use either TVs or monitors that were built around CRTs that were built to the same specifications as TVs. While (traditional standard definition) TVs ...
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  • 12.4k
25 votes
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What is the difference between the Commodore 1701 and the 1702?

The 1701 and 1702 are virtually identical. They have the same specs, tube, inputs, casing, and manufacturer. The only real difference is the 1701 is older (1982 to early '83, 1702 is late '83) and the ...
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  • 4,062
24 votes

Adjusting focus for old CRT monitors

The EHT (extra-high-tension) circuits used to drive colour CRT displays run at 25kV (kilo-volts), and the capacitors contain enough stored charge to kill you stone dead if you touch the wrong thing, ...
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  • 2,779
23 votes
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Computers with integrated monitor (all-in-one form factor)

It's a little cheaper to build all-in-one units because you only need one cabinet and one power supply, and you need fewer cables and connectors and supporting electronics. And back then, people didn'...
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21 votes

What is the correct name for the old green/amber-on-black monitors, and what are the best vintage models to look for used?

Are they called "monochrome" monitors, or something else? Yes. Monochrome covers all that paint in Amber, Green, Blue or white on black. What I want is one of those with glowing green ...
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  • 173k
21 votes

Why didn't early color TV sets accept RGB input?

Early colour TVs predated VCRs and home computers by many years. Even if it did not cost much, adding an RGB input would still be a cost for something that no one would use. However, it would have ...
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  • 1,812
20 votes

Why didn't early color TV sets accept RGB input?

Many TV designs up into the 1970s were so called live chassis designs, which used one leg of the mains input as a reference ground. This saved materials and weight - given some early color TVs used ...
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19 votes
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Can the wrong sync frequency really destroy a CRT monitor?

Horizontal deflection circuit is intended to make linearly increasing current in the deflection coil. At the end of ray scanning from left to right, the deflection coil should be re-magnetized in a ...
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  • 9,326
19 votes

Was the picture area of a CRT a parallelogram (instead of a true rectangle)?

Canonically in NTSC standards the drawn lines are tilted slightly so that the start of the odd field starting at the left is perfectly level with the top of the even field starting in the middle ...
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19 votes
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Did any computer allow overscan on a CRT monitor?

The Commodore Amiga (all models) had hardware support for overscan on CRTs. This was accessible to the user through the Preferences settings, as shown in the dialog panel below. The Preferences ...
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  • 57.3k
18 votes
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What's the name of this CRT monitor?

It’s a regular 80s-era TV set, specifically a Ferguson MC01 (from a 1986 Argos catalogue, see this article): the buttons are volume, brightness, contrast, colour, and channel selection buttons. This ...
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  • 96.6k
18 votes
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Why does my CRT whine?

My Amstrad CTM644 CRT 'monitor', makes a high pitched whine [...] My research indicates that this is just the scanning frequency of the tube, The ~15 kHz line frequency is the most likely source. ...
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  • 173k
17 votes
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What is the correct name for the old green/amber-on-black monitors, and what are the best vintage models to look for used?

A "monochrome" screen refers to any display which only displays one colour, based on the type of phosphor used. The type you are after is more specifically called a "green screen" ...
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16 votes

Why did 80x25 become the text monitor standard?

The 80 columns comes via IBM terminals such as the 3270, which themselves got it from IBM punched cards. There was no particular reason to pick 80 over some other width for punched cards except that ...
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  • 9,380
16 votes

Physical resolution and control of old VGA (color) CRT monitors

What was the phosphor resolution? The usual specification quoted for CRT resolution is the 'dot pitch', or distance between groups of RGB phosphor dots. Here are some examples of IBM monitors ...
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  • 5,813
15 votes

Was the picture area of a CRT a parallelogram (instead of a true rectangle)?

IIRC, the electron gun was actually installed in a position where it was rotated slightly relative to the tube, to compensate for this effect, so the scan lines did end up being horizontal.
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  • 49.6k
15 votes

Why does my CRT whine?

Basically it's the 15625 Hz sawtooth-like signal that drives the horizontal deflection coil, that is heard because the generated magnetic field moves the coil. It's a problem with all TV CRT, on some ...
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15 votes

Why did some video games apparently use "interlaced" video modes?

TL;DR: It's not about what a console can deliver as it is what a TV can display. Classic (pre digital) TV sets could only receive and display interlaced frames. So no sense in producing a non ...
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  • 173k
15 votes

Why were animated screensavers used instead of a black screen on CRT monitors?

A common usage pattern in the 1990s was that someone who was stepping out of the office but would either stay nearby or else be back soon would trigger the screen saver, but someone who was leaving ...
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  • 28.1k
14 votes
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Choosing a monochrome color at the monitor?

A form of this was used extensively for avionics displays. Known as the penetron (stop giggling), the CRT used a single gun and dual phosphor coatings (red and green). Each frame was drawn in two ...
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  • 8,930
14 votes

Ideal resolution for color computer on PAL/SECAM

In the early 80s, cost of RAM for the framebuffer was the dominant factor, closely followed by RAM bandwidth. The difference in resolution between NTSC and PAL systems is minimal in comparison to ...
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  • 2,072
14 votes
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Performance characteristics of the DEC Type 30 graphical display

This might just be stating the obvious, but Type 30 manual linked in the question describes the device as a random-position point-plotting cathode ray tube. Nowhere does the manual suggest it's a ...
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  • 28.3k
13 votes
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Price of early color monitor versus TV

Based on a quick perusal of the November 1982 edition of Acorn User — a user base reliably rich enough at least to consider a monitor — options then included (size unstated where the advert omits it, ...
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  • 32.5k

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