Questions tagged [graphics]
For questions regarding graphical - as opposed to text - processing and display.
9
votes
4answers
264 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 ...
3
votes
1answer
141 views
How is the 320x200x16 graphics mode mapped in the IBM PCjr?
I've read that the PCjr supports a 320x200 pixel mode with 16 colors. But what I can't seem to find is how much memory that takes, how it's organized (chars?) or where it's located in memory.
I'm ...
14
votes
1answer
801 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 ...
4
votes
0answers
105 views
Is there a comparative analysis of the evolution paths of chips inheriting from TMS9918?
This is primarily about VDP from the Sega Master System game console and video chip from the MSX 2 series computers.
Specifically about Yamaha YM2602 (aka Sega 315‑5124) and Yamaha V9938 respectively.
...
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. ...
3
votes
1answer
192 views
Cannot find repGL source anywhere [closed]
As stated here, repGL (a library to emulate SGI's IrisGL on top of OpenGL) can be found at this address: ftp://ftp.informatik.uni-oldenburg.de/pub/grafik/.
I can see the file, indeed (it's named ...
3
votes
1answer
245 views
Is screen wrap on the NES a fault of the OAM?
On NES games such as The Legend of Zelda and Metroid, entities that get to close to the edge of the screen, whether that be the top, bottom, left, or right side wrap around to the other side of the ...
16
votes
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 ...
24
votes
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 ...
1
vote
0answers
177 views
How do I compile C code with the IRIX X Window System?
I have typed out a rather large file in C code that is defining OpenGL graphics and will draw a triangle on the screen. While I know all of the functions of the X Windowing System, I do not know how ...
5
votes
1answer
212 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. ...
11
votes
1answer
417 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 ...
5
votes
3answers
262 views
Do 3d consoles run OpenGL?
I am talking about the earliest days of the first generation of 3d game consoles, such as the Playstation, N64 and Sega Saturn.
Now these consoles are like a pc, the ps3 (and 4?) run OpenGL, and Xbox ...
9
votes
4answers
2k views
Why aren't each pixel's bits stored sequentially on the SNES?
When storing graphics in a non-sequential/planar format (like the SNES does), converting to an 8-bit value representation requires first accessing multiple bytes (amount depending on bits-per-pixel), ...
8
votes
1answer
579 views
What happens when PS1's “Fearful Harmony” is triggered?
When inserting an incompatible disc into a Playstation, after waiting awhile the screen will display very corrupt graphics and unsettling music will begin to play. This is unofficially referred to as "...
4
votes
2answers
302 views
How does the PMD 85 display colour or greyscales?
I stumbled across this computer in an article on hackaday, Home computers behind the Iron Curtain and since it has this bizarre resolution, I looked closer into it.
Some claims from Wikipedia:
...
4
votes
0answers
119 views
How to use IIgs enhanced graphics modes in AppleSoft BASIC with System 6?
There are many packages that let you use the enhanced graphics modes of the IIgs in AppleSoft BASIC. However most packages like Iconix do not like System 6 so they have to run off disks and not the ...
2
votes
1answer
372 views
How does the SNES (Super Nintendo) calculate the address of a character?
The SNES has a PPU (Picture Processing Unit) which comprises VRAM, OAM (Object Attribute Memory), and CGRAM (Color Graphics/Palette RAM). These are used to represent tiles, tile maps; attributes for ...
2
votes
2answers
325 views
What made channel bleed so bad over coaxial cable?
Using coaxial cable, there was a really bad channel bleed - as shown in this video, putting a NES on channel 3 caused distortion to the static on channels 2 and 4-7.
This distortion was so bad, you ...
11
votes
2answers
350 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.
...
3
votes
2answers
366 views
How were individual bit planes scrolled on the Amiga (OCS)?
Back in my early Amiga days (A500), I remember coding simple demos that would use the dual-playfield mode and scroll them around (at a sweet 60FPS). It was pretty trivial to do with languages like ...
14
votes
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?
7
votes
4answers
370 views
An old DOS application that allowed to create cards, posters, invitations, etc
I remember an old (90's) program, run in DOS, that allowed its user to create posters, invitations, cards, etc. It had mouse support and its own GUI with windows, bars, fields, etc.
The work started ...
3
votes
1answer
304 views
Identifying an old one-bit image file format
I've found some code for reading an old image format, and I'm trying to figure out what format it is. Attributes of the file format I've deduced from reading the code:
The image file begins with a ...
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 ...
32
votes
4answers
6k 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,...
10
votes
3answers
567 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 ...
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 ...
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 ...
5
votes
2answers
472 views
Is there really 1MiB of physical memory in the motherboard of a PC AT/XT?
This is a question that has been puzzling me for a while.
What happens with devices like graphic cards that have their own memory chips? Do these cards read/write from their own internal memory to/...
19
votes
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 ...
15
votes
4answers
4k views
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=...
12
votes
1answer
665 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 ...
5
votes
4answers
765 views
What is the (usually lower quality) “software rendering” mode visible in so many “second-generation” FPS games?
During a conversation, a friend of mine sent me this picture:
It's the first Thief (I guess), with so-called software rendering.
I already experienced this effect in Quake 1-2 and to an extent, in ...
20
votes
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 ...
3
votes
1answer
396 views
SNES / old graphics: merging sprite's with background [closed]
I have one question about how old computers or consoles like Super NES merged background layer(s) and spirites. Or another way - how layers were merged to not overload a PPU / CPU? OR how about ...
23
votes
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 ...
19
votes
3answers
1k 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 ...
9
votes
5answers
781 views
How can I adapt a digital CGA/C128 signal (RGBI DE-9) to a modern monitor?
IBM's CGA and the Commodore 128's RGB video output both use a DE-9 connector. How do I adapt the CGA video output from an IBM XT 5160 or Commodore 128 to a modern monitor?
11
votes
1answer
670 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 ...
5
votes
2answers
313 views
Spectrum clones 512x192 mode usable text resolution
The original ZX Spectrum has a resolution of 256x192, for 32x24 text. Some later clones add a 512x192 mode. The most obvious thing to do with that is try to display 64x24 text. According to https://en....
16
votes
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 ...
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 ...
16
votes
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 ...
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 ...
5
votes
2answers
618 views
Graphics Editor for 16-Bit Games
Which programs or tools were used to create the sprites and backgrounds for 16-Bit games like those on the Super Nintendo or the Sega Genesis?
9
votes
4answers
1k views
Actual resolution of composite video monitors
Many early computers used TV sets as monitors. With an NTSC TV set, you could really only count on about 200 scan lines of vertical resolution, and for horizontal resolution, maybe 192 color clocks at ...
16
votes
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 ...
6
votes
1answer
216 views
Strange visual behaviour on SGI IRIX
I've installed IRIX on SGI Octane and have screen looking like this:
(I mean the stripes on all elements of the screen, which doesn't seem as a result of CRT monitor - the screen looks normally on ...
20
votes
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 ...
