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40 votes
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Why were early personal computer monitors not green?

The reason was cost, since neither the original PET nor the TRS-80 required the extra high resolution and finer dot pitch found in more expensive computer monitors. Virtually all of the computer ...
Brian H's user avatar
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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 ...
Grabul's user avatar
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27 votes
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How did humans interact with early computers without screens or sensors?

I understand that either nonelectromechanical computing devices (analog) or electromechanical computing devices (digital) were ever developed by humans. That distinction is a bit off, mixing ...
Raffzahn's user avatar
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26 votes

Why were early personal computer monitors not green?

The answer, as always, was cost. 'White' CRTs were cheaper because they were used in B/W TV sets. The color itself has no impact on resolution, but TV tubes didn't need to be as sharp so they could be ...
Bruce Abbott's user avatar
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21 votes
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Amiga multitasking - different resolution for each program on screen dragging

Is there some kind of upscaling happening for the lower res program, No. or each one retains it own res? Yes. I cannot understand how would be possible to send such a mix of resolutions to a ...
Raffzahn's user avatar
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21 votes

How do 80x25 characters (each with dimension 9x16 pixels) fit on a VGA display of resolution 640x480?

CRTs don’t have a fixed pixel resolution; early CRTs have fixed timings (25.175 MHz and 28.322 MHz for VGA). VGA 80×25 text mode really does produce 400 lines of 720 pixels, as you determined, with a ...
Stephen Kitt's user avatar
21 votes
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How do 80x25 characters (each with dimension 9x16 pixels) fit on a VGA display of resolution 640x480?

How does VGA manage to show 720x400 resolution text on a 640x480 display? This might be your basic misunderstanding here. Displays as used back then and what VGA was designed for, are not a fixed ...
Raffzahn's user avatar
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20 votes

Amiga multitasking - different resolution for each program on screen dragging

The Amiga uses a coprocessor called "Copper", which runs synchronous with the video output. It can be setup to write data to the custom chip registers at a specific place on the screen. In ...
Edders's user avatar
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17 votes

How did humans interact with early computers without screens or sensors?

Switches and lights. Here's the panel for an IBM 650: The top row of dials are used to configure in decimal values (the IBM 650 being a decimal machine). The repeated columns of 5 lights with 2 on ...
RETRAC's user avatar
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16 votes
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Saving the screen on a ZX Spectrum without the prompt

One simple answer is to copy the screen to a buffer elsewhere in memory and save it from there. 10 CLEAR 58455 ... generate the screen image here ... 900 FOR n=0 TO 6911 910 POKE 58456+n, PEEK (16384+...
john_e's user avatar
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16 votes
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How big is the screen of the Amstrad CPC 464?

The CPC 464 was sold with either a green-screen monitor, the GT64, or a colour monitor, the CTM460. The former has a 12” tube (11.4” visible), the latter a 14” tube (13.5” visible). The screen wasn’t ...
Stephen Kitt's user avatar
13 votes
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Can the BBC be programmed to a half-size mode 1 screen mode with 16 colours instead of 4?

With all these 'or' in between and jumping between various points, requirements and conclusions, it's a bit unclear what your're looking for. If this is about most colour with least memory, then the (...
Raffzahn's user avatar
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12 votes
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Why green phosphor instead of amber?

According to this answer to a question about the early use of green monitors they had a severe disadvantage in that you had to choose between 'too dim' and 'rapid burn-in' whereas amber could display ...
Raffzahn's user avatar
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12 votes

Is there a screen recording application for Windows 3.1?

There was Lotus ScreenCam, which was initially released for Windows 3. It used its own SCM format, which only recorded events and optional audio. Later versions (I’m not sure which, or whether this ...
Stephen Kitt's user avatar
11 votes

Connecting a Vintage Monochrome Monitor to a Modern PC

Does anyone know hard or time consuming it would be to achieve this? Assuming you have a modern PC with VGA out, or you can put in a graphics card with VGA out, it's not hard at all, if you know a ...
dirkt's user avatar
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10 votes
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Connectors for green screen versus color monitors

The very short answer is no, because no “green screen” standard is compatible with VGA (which is where 640×480 was introduced). The slightly longer answer is yes, but only in a very small number of ...
Stephen Kitt's user avatar
10 votes

How did humans interact with early computers without screens or sensors?

From the point-of-view of someone at the time, you interacted with early computers in the usual way. From the 1930's onwards, business and some science used IBM and Remmington-Rand mechanical ...
Owen Reynolds's user avatar
9 votes
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Connecting a Vintage Monochrome Monitor to a Modern PC

The Apple IIc monitor (A2M4043) mentioned in the question takes a composite video signal. Some older laptops and graphics cards output composite or S-Video either directly or through a breakout cable. ...
snips-n-snails's user avatar
9 votes

Amiga multitasking - different resolution for each program on screen dragging

On most computer and video game systems from the Amiga's era and before which were capable of supporting multiple display modes, changing display modes or parameters that were made while the beam was ...
supercat's user avatar
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8 votes

Why were early personal computer monitors not green?

A few points to expand on previous answers: In those days, resolution wasn't limited by phosphor, but by video bandwidth (and video memory). A standard TV had a bandwidth around 2-3 MHz, enough ...
jeffB's user avatar
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8 votes

How do 80x25 characters (each with dimension 9x16 pixels) fit on a VGA display of resolution 640x480?

They don't fit to 640 pixels as VGA text mode is not 640x480. 640x480 is simply the one of the modes, but not the only mode available. It just happens to be the highest and most commonly known format. ...
Justme's user avatar
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7 votes

In the Amstrad CPC's Mode 0, what was the design rationale for interleaving the pixel bits?

According to the CPC schematic, the Armstrad uses a gate array to generate video, so we'd need to know how this gate array is programmed for an exact explanation. But expanding on the comment of ...
dirkt's user avatar
  • 28.2k
6 votes

Connecting a Vintage Monochrome Monitor to a Modern PC

VGA was a huge and very bold rejection of NTSC! TLDR of this whole history section: VGA and NTSC have nothing to do with each other. VGA was a blank-sheet design that smashed NTSC limitations with ...
Harper - Reinstate Monica's user avatar
6 votes

Square pixels and TV output

Besides TEMLIB's excellent answer relating to the physical characteristics of the TV, it's also worth pointing out the effects of the video input itself as well. For analogue video input, the picture ...
Muzer's user avatar
  • 1,782
5 votes

How did humans interact with early computers without screens or sensors?

There have been many different kinds of I/O devices since the early years: Indicator lights (often coloquially referred to as "blinkenlights") Front panel toggle switches and pushbuttons Punched tape ...
Greg Hewgill's user avatar
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5 votes
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BBC Micro split mixed graphics modes, could Mode 7 teletext be mixed with them?

TL;DR - Yes, you could No, as it was a clever hack that caused a colour depth change, rather than a wholesale mode change. It might be possible to find/create a different hack to mix mode 7, but it's ...
Greenonline's user avatar
  • 4,386
4 votes

How did humans interact with early computers without screens or sensors?

The Harwell Dekatron is an excellent example of this type of machine, not least because it was designed for simplicity and reliability rather than speed, and this in turn makes it easy to understand. ...
Chromatix's user avatar
  • 16.8k
4 votes

How did humans interact with early computers without screens or sensors?

When your memory device is literally "a screen", you can just look and see what is held in memory. (I think, but can't find a reference right now, that actually the display tube was a mirror of the ...
dave's user avatar
  • 35.9k
4 votes

Connecting a Vintage Monochrome Monitor to a Modern PC

Creating a composite signal for a monochrome monitor should be quite easy. I remember using 4 or 5 resistors to mix green, brightness, HSync and VSync from a 9-pin EGA output to construct a perfectly ...
fraxinus's user avatar
  • 1,324
4 votes
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What was the first control display unit with selector keys around the display?

Almost certainly the Royal Navy's Comprehensive Display System. Although it did not have controls around the entire display, and the controls were generally momentary toggle switches, not buttons, it'...
Maury Markowitz's user avatar

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