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93 votes

Why were those colors chosen to be the default palette for 256-color VGA?

TL;DR: It's All About How To Look At the Palette That way it doesn't look any hideous and ugly, or does it? How Come? What is the origin of the default 256-color VGA palette? IBM's BIOS code :)) ...
Raffzahn's user avatar
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72 votes
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How do DOS games like DOOM benefit from a PCI graphics card?

DOOM itself doesn’t do anything special to benefit from PCI graphics cards. It runs faster with PCI graphics cards (and VLB, AGP, and PCI Express cards) than with ISA graphics cards because the ...
Stephen Kitt's user avatar
50 votes

Why doesn’t my VGA-to-HDMI converter work with my 286 PC?

The manual says that the smallest resolution it can handle is 800x600. That is almost certainly the key. Original VGA supported 640x480 16-colors and 720x400 (essentially a small step up from the ...
manassehkatz-Moving 2 Codidact's user avatar
34 votes
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How did DOS games manage to have multiple background layers?

Seems like VGA only has one background layer, it appears to be a typical bitmap screen like most home computers of the 80s (Amstrad CPC, Commodore 64 etc.) where each pixel's color is stored in a ...
phyrfox's user avatar
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30 votes
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Why was NEC able to wrestle PC graphics standards away from IBM?

VGA was introduced in 1987 with IBM's PS/2 line. NEC and VESA developed SuperVGA in 1988, but at the time it used the old and slow 8/16-bit ISA bus. Improving video performance was a top priority ...
snips-n-snails's user avatar
30 votes

How do DOS games like DOOM benefit from a PCI graphics card?

(When selecting an answer, use Stephen's - I just put this here because it is too much text for a comment) Most Important: It's a Game of Raw Numbers. We can ignore more complicated stuff and simply ...
Raffzahn's user avatar
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29 votes

Why did Super-VGA offer the 5:4 1280×1024 resolution?

VGA's 640x480 mode was the first to offer square pixels and an exception among all VGA modes available (320x200, 640x200, 640x350 and 720x400 for Text). Square pixels weren't the standard back then. ...
Raffzahn's user avatar
  • 213k
25 votes

Why were those colors chosen to be the default palette for 256-color VGA?

The VGA default palette in the 256 colour mode (Mode 13h) first has 16 color entries from CGA (which is also same as default 16-color EGA palette and the only palette for 320x200 EGA mode) Next 16 ...
Justme's user avatar
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22 votes

Is the s-video output on the Commodore 64 different from "normal" s-video?

The 64 has separate outputs on the video port for luma and chroma which you can adapt to an S-Video output. There are a few caveats, however. The chroma signal is a bit "hot" compared to the S-Video ...
mnem's user avatar
  • 4,517
21 votes

What video connections were common in Europe?

In the UK in the 1980s and the early 1990s, no video input at all was common. Early video recorders and set top boxes (for the new digital channels) would use RF out. You would disconnect the aerial ...
badjohn's user avatar
  • 2,014
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
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 ...
Raffzahn's user avatar
  • 213k
20 votes

What video connections were common in Europe?

Up until ~1980 the only connectors TV sets had were Belling-Lee type antenna in. So most VCR and next to all home computers did use RF modulated output toward the TV set (*1). This included even cable ...
Raffzahn's user avatar
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20 votes
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Do all VGA cards implicitly support CGA and EGA?

All VGAs support the “official” CGA and EGA modes, so most CGA and EGA games work fine. However, compatibility can only be relied upon at the BIOS level; a VGA can be implemented without strict ...
Stephen Kitt's user avatar
20 votes
Accepted

What is the most accurate way to map 6-bit VGA palette to 8-bit?

The most accurate way of course depends on what is the purpose. No way is perfect and there is no one true method for all purposes. First of all, how the VGA works, is that it used the INMOS G171 ...
Justme's user avatar
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19 votes
Accepted

With a 15 kHz video signal (240p or 480i), does VGA have any real-world advantage over S-Video?

S-Video relies on colour transformation from RGB to YUV, and then takes the U and V and modulates them using a colour subcarrier. The TV has to undo all these steps in order to get the original RGB ...
mcleod_ideafix's user avatar
17 votes

Invert LCD screen in DOS 5.0

Some laptops have built-in support for inverting the screen in one form or another; Toshiba laptops for instance have a setup menu to configure gray-scale translation and inversion, as well as a pop-...
Stephen Kitt's user avatar
17 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 ...
Bruce Abbott's user avatar
  • 6,635
17 votes
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What are the blinking rates of the caret and of blinking text on PC graphics cards in text mode?

Yes, your hunch is correct. MDA, original card from IBM, reverse-engineered from schematics : The cursor blink signal is not handled by the Motorola 6845 CRTC. It is handled by dividing VSYNC with ...
Justme's user avatar
  • 28.3k
16 votes
Accepted

What video connections were common in Europe?

Before SCART, European TVs often had not video input at all or S-Video on 6-pin or 8-pin DIN sockets (not Mini-DIN). Cinch composite was uncommon until VCRs came out. After that the old S-Video ...
Janka's user avatar
  • 2,152
16 votes
Accepted

Game Boy DMG to VGA

A direct connection is not going to work - The Gameboy's pixel clock is much too low to drive a VGA screen: GameBoy VGA Pixel clock 4 MHz 25 MHz V-Sync 60 Hz 70 Hz H-Sync 9 kHz 31 kHz So, in a ...
tofro's user avatar
  • 33k
16 votes
Accepted

For fast scrolling DOS games, when was Mode13h preferred over Mode X?

[I]s there ever a circumstance where Mode 13h is a better choice for fast scrolling DOS games over Mode X? Sure, to start with, any single pixel operation on in Mode X is slower than for Mode 13, as ...
Raffzahn's user avatar
  • 213k
16 votes

Why was NEC able to wrestle PC graphics standards away from IBM?

I think that this was part of the larger trend of IBM losing the leadership of the “PC”, especially after the PS/2 and the MCA debacle (although the PS/2 line did introduce many new features which ...
Stephen Kitt's user avatar
15 votes
Accepted

What DOS games used Mode X as described by Michael Abrash?

Many PC pinball games use Mode X, notably Pinball Fantasies, Pinball Illusions and Epic Pinball. Nerdly Pleasures also has a comprehensive post on games using “unofficial” resolutions, which includes ...
Stephen Kitt's user avatar
15 votes

What is the most accurate way to map 6-bit VGA palette to 8-bit?

Justme detailed some of the reasons that the exact conversion method probably doesn't matter. Another reason is that you are probably going to interpret the 8-bit output according to the sRGB standard,...
benrg's user avatar
  • 1,951
14 votes
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How can a Z80/8080/6502 use VGA?

Preface: The question sounds as if you're missing a basic understanding of interfacing and communication between different chips/systems. At the core it can't be answered without a whole course in ...
Raffzahn's user avatar
  • 213k
14 votes
Accepted

How to use "AND," "OR," and "XOR" modes for VGA Drawing

Running your code as-is on a real 286/VGA (Cirrus Logic CL-GD5420) produces this image: Inserting one dummy read before the second fill cycle (just mov ax, es:[0]) gives the image you were expecting: ...
Vlad's user avatar
  • 1,541
13 votes

Why did Super-VGA offer the 5:4 1280×1024 resolution?

1280x1024@24-bit fits in 4 MiB. Why wouldn't you take extra screen space? Keep in mind that games didn't usually run in 1280x1024 at the time. Back before LCDs became the dominating screen technology,...
Luaan's user avatar
  • 767
13 votes
Accepted

How do I stop flickering in mode 13h?

Yes, you need to synchronize framebuffer updates to happen so that the framebuffer area is not updated by your code while that area of framebuffer is being drawn on screen. Port 03DAh has bit 3 ...
Justme's user avatar
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