For questions regarding graphical - as opposed to text - processing and display.
4
votes
0answers
101 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
221 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
291 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 ...
10
votes
2answers
304 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
262 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
1k 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
316 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
283 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 ...
30
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
468 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 ...
11
votes
2answers
1k 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
436 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 ...
14
votes
4answers
3k 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=...
11
votes
1answer
447 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
523 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
271 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 ...
21
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 ...
18
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 ...
8
votes
4answers
423 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
542 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 ...
4
votes
2answers
259 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
816 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
1k 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 ...
15
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
1k 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
573 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
195 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 ...
10
votes
3answers
719 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-...
10
votes
2answers
271 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 ...
9
votes
3answers
384 views
Did any system natively use 3-bitplane graphics?
Computer and game consoles switched gradually from single-bitplane graphics (2 colours per character) to 2-bitplane graphics (4 colours per character), to eventually 4-bitplane graphics (16 colours ...
25
votes
5answers
1k 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 ...
12
votes
2answers
438 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 ...
28
votes
2answers
1k 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 ...
21
votes
3answers
3k 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, ...
1
vote
0answers
352 views
How were 3D effects created before GPUs? [closed]
Games like Super Mario 64 were revolutionary: full, round, hi-definition 3D models moving in real-time and able to be interacted with. This was because they were designed for machines with separate ...
12
votes
2answers
416 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 ...
22
votes
9answers
1k 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, ...
10
votes
1answer
266 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. ...
13
votes
1answer
124 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 ...
23
votes
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 ...
10
votes
1answer
383 views
Recommendations for high quality cheap RF demodulator
Does anyone have recommendations for a specific inexpensive RF demodulator that's higher quality than your standard VCR (and maybe a little bit smaller)? Like any old equipment floating around that ...
27
votes
1answer
2k 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 ...
11
votes
1answer
319 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 ...
6
votes
4answers
303 views
Hercules to COM<->USB adapter - is it possible?
I have a 486 (also another 286 mainboard) with a Hercules card, the plug is the same as RS-232. Is it possible to connect the output with serial port USB adapter and simulate Hercules-compatible ...
