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Questions tagged [graphics]

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

4
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0answers
102 views

What would happen if the DHR jumper was enabled on a Rev A Apple //e?

The Apple //e originally did not support Double HiRes graphics (DHR). The engineers realized they could double their hires and lores X resolution shortly after the introduction of the machine, so the ...
2
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1answer
194 views

SNES PPU die photo

The heart of many classic home computers and game consoles was the graphics chip, yet these tend to be less well-documented than the corresponding CPUs. Still, there are die photos of two of the most ...
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3answers
4k views

When did hardware antialiasing start being available?

An important step towards 3D gaming was the ability to scale sprites or tiles by nonintegral factors. Examples of the former from the eighties were the arcade games Pole Position, Outrun, Space ...
6
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1answer
279 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. ...
5
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3answers
397 views

Can the Commodore 64 display 26 rows of text?

I seem to remember some demo, or a game, which displayed 26 rows of text (that's one more than the usual text mode resolution of 40x25). My memory of it is very hazy, but at least is corroborated by ...
19
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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 ...
6
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3answers
189 views

Why do we need to acknowledge the interrupt from VIC-II?

A page on how to do raster interrupts includes the following code Irq: LDA #7 STA $D020 ; Turn screen frame yellow LDX #90 Pause: DEX BNE Pause ; Empty loop that "...
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2answers
205 views

Does anyone have an x86 EGA draw pixel routine?

So far, I have gotten by with using the BIOS draw-pixel routine here: http://stanislavs.org/helppc/int_10-c.html This works of course, but I can't imagine that commercial games used this BIOS call as ...
3
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2answers
330 views

EGA style 16 color dithering

I am trying to write a program in C# that will re-create the type of dithering used in many of the old sierra and Lucas arts games. I have looked up many different dithering algorithms and none seem ...
13
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2answers
418 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. ...
5
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2answers
188 views

How to exactly sync to the raster line for a vertical raster split?

Motivated by Wilson's question Can a Commodore 64 use two screenmodes on one scanline? I tried to implement a simple example that polls the beginning of a rasterline and then switches the screen mode ...
17
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2answers
628 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 ...
2
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3answers
459 views

Daisy wheel graphics using the period?

Although it would have absolutely beaten the hardware to death, did anyone ever try to write a graphics driver for daisy wheel printers that would use the period symbol to painstakingly construct a ...
1
vote
1answer
149 views

Could a 6502 use different speeds of RAM in a single machine?

I'm not sure I've entirely formed the idea in my head, but I'll ask anyway... One of the things I learned here in RO is that the BBC gained speed by using faster RAM, thereby avoiding cycle stealing ...
10
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4answers
473 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 ...
14
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5answers
753 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 ...
5
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3answers
166 views

Opening or converting GFA Basic files to something readable?

There is a bunch of GFA BASIC for Amiga files (the source code for Blender's ancestor, Traces, downloadable here: http://zgodzinski.com/blender-prehistory/) that I would like to peek at. Despite my ...
10
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2answers
334 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: ...
5
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5answers
574 views

What systems had the lowest resolution ever that still allowed games to be made?

Just for fun, I wrote my own Chip8 interpreter/emulator and it works. The point is that it works in the terminal, meaning that a pixel is rendered using curses and a # character. For the Chip8 that'...
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?
2
votes
1answer
303 views

When were other inexpensive computers able to recreate “The Amiga Juggler”? [closed]

The Amiga Juggler was the 2nd very popular demo to appear for the Amiga Computer early in its lifespan. The demo was created by Eric Graham (who went on to develop Sculpt3D) using raytracing to both ...
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5answers
1k 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?
4
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1answer
174 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 ...
31
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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. ...
14
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1answer
842 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 ...
3
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1answer
199 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 ...
4
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2answers
316 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: ...
12
votes
3answers
515 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 ...
4
votes
1answer
296 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 ...
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, ...
33
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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,...
25
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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 ...
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 ...
1
vote
0answers
198 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 ...
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 ...
12
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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 ...
5
votes
3answers
273 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
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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), ...
2
votes
1answer
448 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 ...
12
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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 ...
8
votes
1answer
832 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 "...
7
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4answers
412 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 ...
4
votes
0answers
137 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 ...
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 ...
2
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2answers
331 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 ...
3
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2answers
440 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 ...
11
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2answers
396 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
1answer
313 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 ...
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 ...
6
votes
1answer
232 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 ...