Questions tagged [graphics]
For questions regarding graphical - as opposed to text - processing and display.
4
votes
0answers
105 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 ...
17
votes
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 ...
2
votes
1answer
197 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 ...
5
votes
3answers
399 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 ...
6
votes
3answers
191 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 "...
0
votes
2answers
206 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 ...
5
votes
2answers
190 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 ...
2
votes
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
150 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 ...
3
votes
2answers
331 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 ...
5
votes
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
votes
2answers
336 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:
...
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 ...
5
votes
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'...
10
votes
4answers
475 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 ...
4
votes
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 ...
14
votes
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 ...
6
votes
1answer
280 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
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
votes
1answer
297 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 ...
25
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
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 ...
13
votes
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. ...
17
votes
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 ...
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
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
836 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
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:
...
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 ...
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 ...
2
votes
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 ...
11
votes
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
2answers
441 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 ...
16
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
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 ...
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 ...
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 ...
33
votes
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,...
10
votes
3answers
632 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 ...
14
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
511 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
817 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 ...
6
votes
4answers
902 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 ...
4
votes
1answer
470 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 ...
