Questions tagged [video]

For questions regarding hardware and drivers used for video output.

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5
votes
1answer
205 views

Is there a generic VBE driver available for Windows 3.x?

I’d like to run Windows 3.11 on a relatively modern laptop. One problem I have is that the only display driver that works with my hardware is the basic VGA driver, which only supports the rather ...
6
votes
1answer
319 views

Was it ever possible to access the full EGA color space in 200-line modes?

It's long been an established fact that the EGA only had four memory planes, which limited the number of colors on the screen to (24) 16. The best compatible monitors at the time had six TTL color ...
3
votes
1answer
146 views

`DRAW` instruction timing

I asked a question here about CHIP-8 instruction timing, and this answer mentions that DRAW waits for vblank: For Chip-8 code that draws anything, the limiting factor will be the wait-for-vblank that ...
8
votes
2answers
734 views

Could CGA synchronize with vertical blank?

According to http://www.vcfed.org/forum/showthread.php?62049-The-myth-of-the-vertical-retrace-interrupt-on-EGA-VGA IBM first implemented a vertical retrace interrupt on the PCjr in 1984. That ...
29
votes
3answers
10k views

Why do PCs boot in 720x400 resolution?

Using my 21" Trinitron OSD, I can see that the resolution at boot is 720x400. From memory, this weird resolution is extremely uncommon if ever to be seen as a choice on software that supports ...
0
votes
1answer
96 views

How exactly does Leningrad contend the memory?

From what I understand of this answer, the Leningrad delays the Z80 during the M1 cycle so that the video generation circuitry can do its thing. I can see how M1 is "latched" (don't know if that's ...
1
vote
0answers
160 views

Thinking through the design of a TTL video card: what memory chips and how to manage memory? [closed]

Inspired by Ben Eater's "Let's build a video card" aka "World's worst video card" two part projects on YouTube, I was inspired to consider designing a display adapter for my passive backplane TTL mini-...
6
votes
1answer
337 views

What role does the 4-bit shift register play in the Leningrad video generation?

The Leningrad contains a shift register1, which I believe is loaded with data from the bitmap. This part loads 8 bits in parallel, and shifts each bit out in turn on the rising edge of a clock signal. ...
35
votes
2answers
3k views

What mid-1970s to mid-1980s home computers had their graphics characters added to Unicode 13?

The Unicode 13.0.0 release notes mention among the symbol additions: 214 graphic characters that provide compatibility with various home computers from the mid-1970s to the mid-1980s and with early ...
5
votes
3answers
743 views

How does the Apple II read lines for video display from the text-mode frame buffer?

(This question applies also to the low-resolution graphics video buffer, since that uses the same frame buffer as text mode, just displaying it differently.) As described on page 1-12 et seq. of The ...
9
votes
4answers
3k views

Is it possible to swap the Apple //c's monochrome CRT tube for a color one?

I just love the Snow White industrial design language of the Apple //c, especially when paired with the Monitor //c. It is a classic design that doesn't show its age. I've even recently seen them ...
5
votes
2answers
897 views

Could early nineties PCs access raw CD bitstream?

In the early nineties, as discussed in What specific technical advance(s) allowed PCs to play "Full-screen full-motion" video? it became commonplace for PC games to use the storage capacity ...
18
votes
2answers
3k views

How did the Sega CD decompress video?

In the early nineties, Sega released the Sega CD, a.k.a. Mega CD, an add-on that attached a CD-ROM drive to the Mega Drive a.k.a. Genesis. Its primary or at least most conspicuous use was for full-...
2
votes
1answer
174 views

What is the format of the Apple 1 character set ROM?

What is the format of the video character ROM used in the Apple 1?
18
votes
7answers
3k views

Cost of unrestricted sprites

All the game consoles of the second through fourth generations, and several early home computers, had sprites, which were valuable though costly, e.g. the VIC-II spent 2/3 to 3/4 of its area on ...
5
votes
2answers
249 views

Could monochrome systems produce better output for monitors than TV sets?

Many classic computers could optionally use a TV set as the display. At least in the early (pre-SCART) days, the TV would typically only have RF input, but if you were using a monitor, you could get a ...
6
votes
2answers
592 views

What was the title safe area on PAL TV sets?

Computers that used TV sets for display, needed to worry about the title safe area. By consensus, on NTSC sets, it was 200 scan lines, or 192 if you wanted to play it really safe. What was the ...
12
votes
1answer
492 views

How did the Apple 1 video circuit work?

One of the major innovations of the Apple 1 when it was released in April 1976 was that instead of using a serial interface requiring an expensive external terminal it had a built-in 40×24 text video ...
5
votes
1answer
313 views

(How) can I boost my ZX81 video output with an external device?

I bought a small LCD TV today in part to use with my retro computers. My Sinclair ZX Spectrum 48k works perfectly with it - I can manually fine tune Channel 36 as shown in this video. With the ZX81 I ...
9
votes
2answers
1k views

What was the screen refresh rate of the Lisa and original Macintosh?

According to https://www.folklore.org/StoryView.py?project=Macintosh&story=Joining_Apple_Computer The Apple II displayed white text on a black background. I argued that to do graphics properly ...
43
votes
2answers
9k views

Why were some early PC 3D cards unsuitable for 2D graphics?

Some of the early PC 3D graphics cards such as the 3dfx Voodoo Graphics cards had a passthrough port to enable them to switch to a secondary card to display 2D graphics. I am curious to know why these ...
9
votes
1answer
262 views

What was the purpose of the Apple /// interlace mode?

I know that a video interlace mode was available on the Apple /// prototype and eventually on the Apple ///+, but I haven't seen anything that says what it was for. Did it provide a higher resolution ...
6
votes
4answers
564 views

Are there standard DIN pinouts for cassette and video ports on early Japanese 8-bit computers?

I have several different Japanese 8-bit computers, and they use similar DIN connectors for video and cassette I/O: Composite video: 180° 5-pin DIN: Fujitsu FM-7, NEC PC-8001mkII Color TTL (digital) ...
6
votes
2answers
801 views

GPU chip implementation on CPU - will it be faster? [closed]

So, modern video cards include two devices - a video signal generator and a graphic accelerator. The first of them converts data from video memory into MDA / CGA / VGA / RCA / DVI / HDMI / etc format....
11
votes
3answers
604 views

What are the Ultra-Highres registers in ECS and AGA for?

The Amiga custom chip set, in its ECS and AGA versions, seems to contain some registers for what is called an "Ultra-HighRes/DUAL" mode: DFF078 SPRHDAT W Ext. logic UHRES sprite pointer and ...
13
votes
2answers
623 views

Atari ST DRAM timing puzzle

From the Atari SM124 Monochrome Monitor Service Manual, I get that the video signal timing for one line is 20µs. With the horizontal resolution of 640 pixels, this gives a 31.25ns pixel clock. Using ...
37
votes
8answers
12k views

Why did computer video outputs go from digital to analog, then back to digital?

While early microcomputers used analog video outputs (often to use a television as a display), higher end machines such as the BBC Micro or Commodore 128 supported a digital RGB (or RGBI) video output....
6
votes
4answers
2k views

High-end PC graphics circa 1990?

I remember CAD being a major driver for PCs with high-end graphics cards; specifically AutoCAD was rising quickly in popularity around 1990 as PCs were able to compete with very costly CAD ...
55
votes
6answers
12k views

How did old MS-DOS games utilize various graphic cards?

Nowadays each graphic card has some driver in operating system that translates some (typically) standard API such as OpenGL, so that programmers use some standardized API code to tell graphics cards ...
3
votes
1answer
206 views

Apple I and II video output to a contemporary TV set?

Is it possible to connect the unmodified video output from an Apple 1 and Apple II (with their non-standard/our-of-spec NTSC sync pulse levels and/or timings) to a (currently in-production and ...
9
votes
3answers
2k views

What is the best option to connect old computer to modern TV

I was exploring different options of connecting both my Atari ST and C64 to a modern TV. I opted for a composite signal passed through a cheap AV to VGA converter, and although the display works, ...
4
votes
1answer
296 views

Atari 1040ST AV video output - blurred and jagged vertical edges

I have an AV cable that connects Atari 1040STE with a AV to VGA converter. For some reason the vertical edges are not sharp, rather jagged or pixelated. I red that old atari would have an issue with ...
8
votes
1answer
996 views

When did MS Windows get Dual Monitor support?

I remember one of the features I admired on the Macintosh in the late 80s was support for multiple displays. First time I saw this was on an SE/30, using the internal display along with a big external ...
1
vote
0answers
94 views

Cannot get K prompt on Timex 1500 [closed]

I started tinkering with a Timex Sinclair 1500 I was given awhile ago. When I first tried starting it, I got a K prompt in the lower left of the screen. I turned it off and did not return to it for a ...
4
votes
2answers
384 views

When were sprites first displayed in the border area?

I assume one of the first undocumented effects on the VIC-II was the ability to display sprites in the (upper and lower) border area. I wonder how and when this was first discovered and used? Was it ...
12
votes
9answers
1k views

Did any machines alternate between two video memory banks?

If a home computer or console has two banks of memory, A and B, then the following design is possible: The video chip only connects to bank A. The CPU connects to both. During active scan line, CPU ...
8
votes
4answers
2k views

Commodore 64 with red and white RCA cable

After discovering my old Commodore 64 in the garage, I wanted to test if it still works. The power light comes on but the video connection to a modern TV is obviously an issue, as mentioned here. Well ...
6
votes
1answer
414 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. ...
7
votes
1answer
454 views

How did the original TRS-80 generate video?

I'm curious how the original (Model 1) TRS-80 generated video. I understand that an RF modulator was used but what kind of circuitry did it use to feed the RF modulator? The TRS-80 Color Computer ...
10
votes
1answer
567 views

Possible cause for C128 A/V output containing faintly coloured columns and failing shortly after?

I recently acquired a Commodore 128. It worked fine for about an hour, in both C64 and C128 mode, at the exception of some coloured bars, before displaying garbage and not booting anymore into any ...
11
votes
1answer
822 views

Can the BBC be programmed to a half-size mode 1 screen mode with 16 colours instead of 4?

Screen Mode 2 on the BBC micro is 160 x 256 with "16"* colours. This uses up 20Kb of memory. Horizontal-rectangular pixels ( 2 x squares each). 4 bits per pixel (0-15 values for 16 colours) Screen ...
8
votes
2answers
1k views

Why did certain color combinations look terrible on the Commodore 64?

As I recall, on the Commodore 64's text mode, if you chose certain colour combinations, the letters would be badly obscured by some kind of interference which seemed to affect each character cell ...
6
votes
5answers
4k views

Is my understanding right about the actual differences between 240p and 480i?

After reading around on the web, including the authoritative site Scanlines Demystified I still am having trouble understanding the difference in signal between 240p and 480i. After reading the wiki ...
78
votes
9answers
13k views

Why were CLIs typically light text on dark background, whereas GUIs typically use(d) dark text on light background?

My experience is that CLIs were typically shown with light text on a darker background. For example, the IBM PC would use white/light gray (depending on your point of view), amber or green (the latter ...
5
votes
3answers
480 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: ...
11
votes
3answers
4k views

Visible resolution of C64 video output, including borders

The VIC-II in the C64 outputs 320x200 pixels inside the borders. What is the full visible resolution including the borders? To clarify, I am interested in the full screen size in units of normal ...
10
votes
7answers
3k views

What Video Chips/Video generation techniques are usable for the Z80?

I'm building a Z80 home computer and I need color graphics for it similar to other home computers such as the C64. I thought that, like Motorola or MOS, Zilog would have a peripheral chip dedicated ...
2
votes
1answer
265 views

Spying on old computer monitor RF signals [closed]

In the mid 80's, several national news outlets showed people able to reproduce a computers monitors screen at least 100ft away. How were early computers compromised like this?
9
votes
4answers
833 views

Columns of text in early microcomputers

As discussed in some previous questions here, 80-column text was established by IBM as the standard for business computing as early as the sixties, but monitors capable of displaying that resolution ...
10
votes
1answer
546 views

VIC-II transistor count

I'm curious about the transistor count of the VIC-II, the video chip in the Commodore 64. According to http://visual6502.org/wiki/index.php?title=Chips_in_our_collection the Atari 2600 TIA chip has ...