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Questions tagged [video]

For questions regarding hardware and drivers used for video output.

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Cannot get K prompt on Timex 1500

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 ...
10
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1answer
185 views

Could suitably-written Apple-I software force bytes into the display shift register, and do modern recreations emulate that?

The original Apple I didn't use RAM to hold the contents of the display, but instead used a group of six 1024-bit shift registers to hold the display contents and a seventh 1024-bit shift register to ...
3
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2answers
300 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 ...
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4answers
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 ...
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3answers
349 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 ...
4
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1answer
186 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. ...
6
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1answer
224 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 ...
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0answers
163 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 ...
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1answer
409 views

On the bbc-micro, a half-size mode 1 screen mode with 16 colours instead of 4 can fit in memory but can the video chip be programmed for it?

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
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2answers
634 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 ...
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5answers
2k 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 ...
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9answers
12k 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 ...
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2answers
312 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: ...
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3answers
2k 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 ...
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6answers
610 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 ...
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1answer
214 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?
8
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4answers
571 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
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1answer
283 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 ...
6
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1answer
746 views

How to connect a Tandy Color Computer to a Composite Monitor?

Ok, I'll admit I'm out of my element on this one. I'm an Atari/Commodore/Apple guy, but I have this Tandy color computer kicking around and a spare Amdek Composite monitor and I thought they would ...
11
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5answers
791 views

Can the wrong sync frequency really destroy a CRT monitor?

I've read in various places that an incorrect signal of the wrong refresh rate can cause physical damage to a CRT monitor, but I've never found an adequate explanation of why this is so. Is this true? ...
11
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3answers
1k views

What specific technical advance(s) allowed PCs to play “Full-screen full-motion” video?

In the early 1990s, the new buzzword for PCs was "Multimedia", and the gold standard for multimedia performance usually talked about was "full-screen full-motion" video playback. Many will remember ...
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3answers
2k views

Were video chips specific to the CPU?

Modern graphics cards are essentially miniature supercomputers in their own right, with their own memory and instruction sets, but in the eighties and late seventies, a very common kind of personal ...
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1answer
377 views

How do Amiga “Monitor” drivers work?

A "Monitor" driver for an Amiga is a file which, when placed in DEVS:Monitors, enables additional screenmodes. The standard PAL or NTSC driver, which provides screenmodes compatible with consumer TV ...
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1answer
277 views

Timex Sinclair 1500 and screen “jail bars”

I have tried to eliminate "jail bars" on the screen after UHF mod to video out (based on that: http://zx81stuff.org.uk/zx81/ts1500_video.html) by adding 460uf 16V capacitor between +5V and GND but it ...
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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,...
5
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3answers
778 views

A different kind of sprite system

Early consoles and home computers that were optimized for games, often provided sprites. From the viewpoint of a game developer, these were good to have, though one always wanted bigger sprites, to ...
17
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4answers
4k views

What video connections were common in Europe?

What video connections were common on European TVs and monitors during the "retro" era? In the USA, first there were none on TVs (RF screw terminals only) and monitors had composite (yellow RCA, CVBS)...
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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?
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2answers
280 views

Timex 2048 RAM contention ULA/video output

I used to own a Timex TC-2048 ZX Spectrum 48K compatible clone. I programmed it in assembly extensively, both for fun and when learning, and also when testing things for writing my own ZX Spectrum ...
13
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3answers
733 views

What is going on in the overscan area of Sega Genesis games?

What is going on in the overscan area of Sega Genesis games? I noticed that different games display different things in the overscan area. I understand this was never intended to be seen. However,...
16
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5answers
942 views

Limiting factor on sprite sizes

Early consoles and home computers that were optimized for games, tended to provide sprites. From a game programmer's viewpoint, these were good to have. Of course, one always wanted more and larger ...
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6answers
1k views

Z80 and video chip contending for random access

Back in the 8-bit days, I used 6502 computers, where the story about memory access was easy to understand. RAM chips of the late seventies and early eighties could do 2 MHz (or a bit more e.g. 2.6 in ...
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4answers
629 views

Video chip for hypothetical 1988 arcade game

I have a project where I aim to create a retro arcade game cabinet, the technology would be ~1988. For now I am planning to only simulate the system on my PC in order to develop the game. The ...
7
votes
1answer
348 views

Is it possible to chain TMS9918 chips to get better graphics?

I'm considering creating a retro system but without requiring the sacrifice of any retro machine in order to get parts. The TMS9918 chip seems the only "generic" retro graphic chip, all other chips ...
23
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9answers
5k views

Graphics chips in 1980

Suppose you were trying to build a computer with a color graphics display in 1980, you have limited engineering resources and time to market is critical, so you want to get as many of the parts off ...
9
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1answer
299 views

What was the difference between the original Video Toaster and the 4000 version?

There were two versions of the Video Toaster hardware: an original one designed for the A2000 and a later one designed for the A4000 which was suitably called the Video Toaster 4000. While I can ...
6
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1answer
421 views

Transistor count of early video chips

There are a number of sources that give transistor counts for different CPUs over the decades. I'm looking for transistor counts for early video chips. in particular, I'd be interested in transistor ...
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1answer
153 views

Using a NeoMagic 256XL with Windows 98SE

I have a Sony Vaio PCG-F560 notebook and I have installed Windows 98SE on it. The only issue is that the display works only in 16 colors mode with 640x480 resolution. I think the problem is that ...
7
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2answers
361 views

Amiga Video Toaster support

What features of the Amiga chipset architecture and/or Amiga OS made it possible to design the Video Toaster run on the Amiga? Why weren't there similar (cost-effective) video products for the PC or ...
20
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1answer
613 views

When does the VIC-II read the sprite data?

This question is about the Commodore 64 and its graphics chip, the VIC-II. Imagine that on a particular scanline, the VIC-II needs to fetch 40 bytes (the background tiles) and since it's a badline ...
8
votes
3answers
433 views

Connecting an Atari 130XE to SM124 monitor

I've got an Atari 130XE 8bit computer that has Composite Video Output. Also, I've got an Atari SM124 monitor designed for the Atari ST 16-bit line of computers. If you look at an Atari 130XE packing ...
9
votes
1answer
413 views

What was the difference between “Video Low” and “Video High” on the VIC-20?

I was reading about the Audio/Video port pinouts of the VIC-20 and I noticed that pin 4 is VID L and pin 5 is VID H meaning Video Low and Video High, respectively. I'm familiar with luma, chroma, etc....
8
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1answer
526 views

Is there a device that will take composite video from a vintage computer and filter it so it is green or amber like the old monochrome monitors?

I know some monitors have a mono/green switch, but I'd like to do this with my 1702. If one doesn't exist, I'll probably try and make one (somehow).
7
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3answers
277 views

Is it possible to have a NTSC picture 240 pixels tall, without any line being hiding by overscan?

On the NES, the system I'm most familiar with, the NTSC models produce 240 lines of video image, but the top and bottom 8 pixels are usually considered to be "hidden" due to overscan. (The actual ...
16
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4answers
1k views

What graphical effects can be created by changing the VIC-II settings?

I read in this answer that one could create graphics effects outside the usual specifications of the hardware by changing the settings of the machine's VIC-II at specific cycles during the video ...
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2answers
562 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 ...
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3answers
6k views

How can I upscale the video output of a Nintendo 64 for low-latency and high quality graphics on an HDTV?

Say I want to hook up a Nintendo 64 console to an HDTV via HDMI or Component. What are my options for upscaling hardware to be able to play the system without low quality or blocky picture and with ...
29
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1answer
1k views

How did the Amiga DCTV work

This is an unusual question since I'll answer it right away because it was a truly unique device and there is absolutely nothing about the technology it used on the internet. I spoke with the hardware ...
8
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2answers
2k views

Alternative to Amiga 520A Video Adapter

So I snagged a North American Amiga 500 on sale at a flea market. I purchased a DSub to VGA connector in the hopes I could get some color output. After getting strange Horizontal sync on my monitor, I ...
54
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6answers
7k views

Reason for the Amiga clock speed

The Amiga used a CPU rated for 8 megahertz, but clocked at 7.14 megahertz. What was the reason for this number? I remember it was something to do with a multiple of the frequency of the video ...