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Questions tagged [graphics]

For questions regarding graphical - as opposed to text - processing and display.

32
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4answers
7k views

What determines the color of every 8th pixel on the Apple II?

On the Apple II there's an interesting way to add a little color to the bitmap, since the high bit select the palette used for the three-and-a-half pixels represented by the byte. Like this: 0: Black,...
31
votes
5answers
6k views

Using DRAM as a camera sensor?

Back in the days when COMECON (RVHP) was cloning digital ICs usually the first wave of such ICs were in a ceramic package with a glass window (similar to EPROM) to check for bugs and stuff while used. ...
29
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2answers
2k views

How did “Ballblazer” pull off fast, smooth, first-person, solid-model 3D on Atari 8-bits?

I remember the first time I saw Ballblazer, the 1984 game, running on a friend's Atari 800. The split-screen 3d graphics and fast action blew my socks off. Looking back, I get the impression there ...
27
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5answers
2k views

Does every retrocomputer and console with NTSC composite output have 'artifact color' ability?

Artifact color is heavily associated with the Apple ][, since that is the only method the machine had to produce a color display. I was looking at the fantastic demo for IBM PC + CGA, 8088MPH, and I ...
27
votes
1answer
3k views

How can I create a split-scroll effect in an NES game?

Games like Super Mario Bros. and Super Mario Bros. 3 were able to scroll the playfield but not the status bar: The status bars are clearly too big to be sprites, yet they don't scroll with the ...
26
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10answers
2k views

Limiting factor on early color palettes

Early color computers typically had a limit of X colors used simultaneously from a palette of Y, a classic example being the Commodore 64 which could do 320x200 monochrome or 160x200 four colors, ...
24
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6answers
8k views

How did the early Macintosh computers update the display?

This question is about the Macintosh 128k, but if you can give an answer which describes one of the other very similar machines, that's good too. The bitmap was 512 by 384 pixels. Assuming that one ...
24
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16answers
2k views

What computers had redefinable character sets?

My first computer was an Exidy Sorcerer, bought in the late '70s. It featured a full keyboard including lower case, on screen text of 64 B&W characters by 30 rows, 2 MHz z-80 processor, up to 48 ...
24
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3answers
4k views

Where did DOS store graphics fonts?

I remember using a wysiwyg print program called Fontasy for CGI graphics in DOS because of a lack of standardized graphics fonts. Companies were selling "font packs" for other type fonts. Prior to Win ...
23
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5answers
2k views

Did any Amiga 500 games or programs (apart from paint programs) use more than 32 colours?

While the Original Chip Set (OCS) and Enhanced Chip Set (ECS) Amiga computers had the 32 x 2 colour EHB (Extra Half-Brite) and 4096 colour HAM (Hold And Mofify) screen modes, where these ever used ...
22
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2answers
1k views

How to obtain 256 arbitrary colors with limitation of 64 per line in Amiga (ECS)?

The game Universe for Amiga boasted ability of use of 256 different Amiga colors available through the ECS chips, with only limitation of 64 colors in halfbrite palette (32 arbitrary + 32 at half ...
21
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2answers
534 views

How do I use shadowed memory to render Super Hi-Res quickly?

The Apple IIgs video memory is controlled by the 1MHz Mega II chip, so directly accessing the Super Hi-Res page in bank $E1 is slower than accessing other memory. How can I render in "fast" memory, ...
21
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3answers
4k views

Is there a simple way to display ANSI art and animation files in a modern terminal window?

ANSI art and animations were prevalent on BBS systems in the late 80s and early 90s, and the ANSI art scene continues to thrive today. There are thousands of ANSI art files, with usual extension .ans, ...
20
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5answers
3k views

What techniques were used to reduce the required re-rendering in 3D programs?

Inspired by this GameDev question. 3D rendering is expensive. With 2D games it's easy to not re-write the buffers every frame, like in Super Mario Bros where the PPU is instructed to render the level ...
20
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7answers
1k views

What implementations of BASIC had a robust flood fill operator?

When I learned BASIC on Elektronika BK, I got fascinated with the flood fill (PAINT) operator: how does it know to get to all nooks and crannies of the shape to fill? I've devised an algorithm, tried ...
19
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9answers
9k views

Can modern AI be used to program impressive graphics effects on very low performance home-retrocomputers, in particular 'A 3D-rotating-cube'

Can modern AI be used to program impressive graphics effects on very low performance home-retrocomputers, in particular 'A 3D-rotating-cube', effects that would be too difficult for a human to ...
19
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3answers
2k views

Why did 80x25 become the text monitor standard?

Prior to the 1981 release of the IBM PC, the VT105 (72x20 1971), VT52 (80x12 1974), and VT100 (80x25 1978) text terminals were used on many Unix machines and the PDP11 (probably the most widely used ...
18
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2answers
3k views

Why do NES sprites flicker when there are a lot of them?

Sometimes, NES sprites flicker when there are a lot of them, like at 1:19 in this video of Super Mario Bros. Why did they do this?
17
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4answers
3k views

Z8410 DMA chip as GPU?

There are basically two ways to design a 2D graphics system: Provide lots of hardware support in the form of tiles, hardware scrolling and sprites, to put together each frame on the fly from a small ...
17
votes
2answers
592 views

What's a good way to implement this “splashing water” effect on the C64?

This pillow fighting game set in Venice depicts the two opponents fighting on a wobbly gondola on a canal. It was apparently known as "Pillow Fight" in English and as "Kissenschlacht" in German, and ...
17
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1answer
1k views

How to check the C64 graphics mode used by Maniac Mansion

I have been investigating the MS-DOS port of the C64's Maniac Mansion game. The original MS-DOS port used the C64-specific character map to draw the various backgrounds in the game. I noticed that ...
16
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10answers
5k views

640x480 color display in 1980

I'm working on an alternate history story in which the protagonists, Silicon Valley computer entrepreneurs, are trying to release a graphical workstation in 1980, with the capability of displaying ...
16
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5answers
2k views

Was 1991's Hellcats the first instance of incremental screen updates?

In case you have never seen it, 1991's Hellcats was a seminal release on the Mac. It ran at full 8-bit color and could, on a newish machine, drive three 1024x768 screens at the same time. Nothing on ...
16
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2answers
2k views

How do CGA emulators for Hercules graphics work?

HGC cards on IBM PCs used to be able to run CGA software by using a CGA emulator. How exactly did those programs work? What were the limitations?
15
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4answers
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Why not one pixel per color clock?

Early home computers and game consoles output video to TV sets. The NTSC color clock frequency is 3.58 MHz. This informed the design of some video systems: http://pineight.com/mw/index.php?title=...
14
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5answers
737 views

Was there any commercially available graphical interfaces before the apple Lisa?

I just finished the Steve Jobs biography and I thought... Was the apple Lisa really the first commercially available Graphical interface? This is just out of interest but I'll be really interested ...
14
votes
1answer
1k views

Why does Ms. Pac-man turn upside down?

Ms. Pac-man is a game where you navigate a small yellow circle around a maze, collecting dots and fruit whilst avoiding brightly-coloured monsters, or ghosts. This time, however, the yellow dot has an ...
14
votes
1answer
813 views

How does Apple ][gs hardware dithering work?

I haven't been able to find an easily comprehensible description of the super hi-res, dithered 16-color, 640x200 mode of the Apple ][gs. I can tell from the references I did locate, this is a ...
13
votes
1answer
3k views

Why do 3D models on the PlayStation 1 “wobble” so much?

A memorable part of the PlayStation 1 experience was “wobbly” 3D graphics, where (supposedly) straight edges would warp, jitter and pulse as the camera panned across a scene. This was especially ...
13
votes
1answer
1k views

How do high-resolution graphics work on the ZX81?

The ZX81 has a display file which is treated rather like a serial file. And the CPU generates addresses which the ULA uses to look up the characters' bitmaps from the ROM (Yes, I know the actual ...
13
votes
2answers
368 views

Can a Commodore 64 use two screenmodes on one scanline?

Many games, for example, Maniac Mansion, or Kissenschlacht, use two screenmodes. Oftentimes, a bitmap mode for the main screen, and a text mode for the lower part which displays scores or whatever. ...
13
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1answer
186 views

Inserting NOPs to improve IIgs shadow copy performance

The answer to this question discussed a technique on the Apple IIgs for copying memory onto itself. The motivation for the technique was to maximize use of "fast" (2.8MHz) RAM over "slow" (1MHz) RAM ...
13
votes
1answer
133 views

Videoprocessor with custom horizontal sampling

I have a variety of videoprocessors (Micomsoft Framemeister, Micomsoft SC-512N1-L/DVI, Sync Strike) to help me get the best possible RGB picture out of my retro computers/consoles. However one issue ...
12
votes
2answers
2k views

How does Atari 2600 TIA display multiple resolutions in Asteroids?

There is probably an easy explanation for this based on some facet of how the TIA generates the display. As is readily visible in the image taken from a real Atari 2600 displayed on a modern LCD, the ...
12
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2answers
538 views

Acorn Electron to VGA/HDMI?

I am aware that there are answers regarding this but they do not seem to answer it for me. A few years back I got a Acorn Electron and it works using the arial for video fine, but I would like to ...
12
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2answers
3k views

Computer graphics before the modern GPU [closed]

Modern computers use a graphics processing unit in order to provide hardware-accelerated graphical operations. Conceptually, I am used to thinking about graphics as a bidimensional array of ...
12
votes
3answers
2k views

What's a good way to implement this “fade” effect on C64

See the beginning of https://www.youtube.com/watch?v=hmfLBAtGAKk. Here's a screenshot: It basically clears characters pixel by pixel both horizontally and vertically. Use sprites for the pixel by ...
12
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3answers
488 views

Why was OCS low resolution limited to 6 bitplanes?

I'm looking for information whether there has ever been an official statement by Commodore back in the days on why the Original Chipset was limited to doing 6 bitplanes only when running in low ...
12
votes
1answer
712 views

Why does the C64 have the following palette?

The Commodore 64 has the following fixed palette of 16 colours: (Your palette may vary due to tuning of screen, etc.) What was the reason for this selection of colours? Are these colours ...
12
votes
1answer
534 views

What was the change to the Apple //e motherboard that allowed for Double HiRes graphics?

Double Hi-Res graphics (DHGR) was a nice addition to the Apple ][ line as it allowed for higher resolution 560x192 graphics with 16 colors in comparison to the traditional 280x192 with 6 colors. It ...
12
votes
2answers
561 views

Ideal resolution for color computer on NTSC

Suppose you were, in the early eighties, designing a color computer to run on an NTSC TV with a free hand to choose the specifications within the limits of the technology of the time. What would be ...
11
votes
1answer
733 views

Where did Sony's 3D graphics hardware in the PS1 originate?

As is well-documented, the Fifth Generation of game consoles brought 3D accelerated graphics hardware to the home market. The main combatants in this particular console war of the mid-1990s were the ...
11
votes
2answers
361 views

What modern image editors support non-square pixels?

Almost all old home computers tend to offer non-square pixels, from wide-pixel graphics modes on the C64/CPC/BBC Micro to CGA's weird not-quite-square 320x200 mode with a pixel aspect ratio of 5:6. ...
11
votes
1answer
398 views

Modern vector display driver?

I have an old Tektronix Type 611 Storage Display sitting in storage, which I would some day like to get working again. I have the full repair manual on microfiche from Tek. It is essentially an ...
10
votes
6answers
2k views

Were there any “off the shelf” graphics chips that supported 2D sprites in the 70's and 80's?

I'm looking for "off the shelf" graphic IC's that supported hardware sprites. By "off the shelf" I mean chips that were designed to be used in various machines and not designed specifically for one ...
10
votes
3answers
592 views

8-bit console horizontal resolution

Some early consoles like the NES and the Sega Master had a horizontal screen resolution of 256. That sounds good for an 8-bit machine, until you consider that a sprite sometimes needs a slightly ...
10
votes
4answers
387 views

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

Back in the DOS days of gaming (more specifically, 80286 - 80486 era), developers typically needed to choose between using the chunky and easier Mode 13h or the more complex "Mode X" that provided ...
10
votes
2answers
284 views

How to use the “darker” CGA palette using x86 Assembly?

For those of you retro developers out there, I am having a hard time figuring out how exactly to select the "darker" color palette in 320x200 CGA mode. Here's what I have so far: setup_cga_graphics: ...
10
votes
1answer
309 views

NTSC scan lines and vertical resolution

From https://en.wikipedia.org/wiki/BBC_Micro "the height of the graphics display was reduced to 200 scan lines to suit NTSC TVs". But NTSC is supposed to have 241 visible scan lines per half frame. ...
10
votes
3answers
885 views

Can artifact color mode create 262,144 colors on Amiga OCS?

This is as a follow-up to my previous question on artifact colors and the excellent answers provided there. The images below show a simple example of artifact colors generated using a single bit-...