41
votes
Accepted
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 ...
- 61.5k
32
votes
Accepted
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 ...
- 3,745
27
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 ...
- 6,773
27
votes
Accepted
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 ...
- 236k
22
votes
Accepted
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 ...
- 236k
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 ...
- 131k
21
votes
Accepted
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 ...
- 236k
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 ...
- 871
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 ...
- 14.1k
16
votes
Accepted
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 ...
- 131k
13
votes
Accepted
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 (...
- 236k
12
votes
Accepted
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 ...
- 236k
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 ...
- 131k
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 ...
- 30.5k
10
votes
Accepted
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 ...
- 131k
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 ...
- 339
9
votes
Accepted
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. ...
- 17.6k
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 ...
- 39.2k
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 ...
- 2,856
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.
...
- 37.2k
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 ...
- 30.5k
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 ...
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 ...
- 1,792
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
...
- 7,049
5
votes
Accepted
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 ...
- 4,500
5
votes
Split screen function before 1970
Yes, at least sort of. For example, here's shot of a display from a 1966 film about the (then quite new) Plato teaching system.
As we can see, the top half is questions and answers that make up the ...
- 5,910
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. ...
- 16.9k
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 ...
- 38.2k
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 ...
- 1,324
4
votes
Accepted
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'...
- 21k
Only top scored, non community-wiki answers of a minimum length are eligible