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25

VGA's 640x480 mode was the first to offer square pixels and an exception among all VGA modes available (320x200, 640x200, 640x350 and 720x400 for Text). Square pixels weren't the standard back then. Adding video modes in later (Super) VGA was kind of a marketing game to offer higher numbers to outpace competition. First it was Colour, like offering 640x480 ...


21

In the UK in the 1980s and the early 1990s, no video input at all was common. Early video recorders and set top boxes (for the new digital channels) would use RF out. You would disconnect the aerial from the TV, connect it to the VCR or STB, and connect the VCR or STB to the TV with another aerial cable. The TV would see it as an extra channel. You might ...


19

S-Video relies on colour transformation from RGB to YUV, and then takes the U and V and modulates them using a colour subcarrier. The TV has to undo all these steps in order to get the original RGB signal. If the subcarrier frequency is not in phase with the pixel clock (as will be the case if using different crystals), then moving artifacts will show up in ...


19

Up until ~1980 the only connectors TV sets had were Belling-Lee type antenna in. So most VCR and next to all home computers did use RF modulated output toward the TV set (*1). This included even cable networks. While Type F connectors where used for more sophisticated equipment, households were still fitted with Belling-Lee. Professional equipment of the ...


19

The 64 has separate outputs on the video port for luma and chroma which you can adapt to an S-Video output. There are a few caveats, however. The chroma signal is a bit "hot" compared to the S-Video standard. The S-Video spec for the chroma line for NTSC is 626.70mVP-P (75% Color Bars), 835.60mVP-P (100% Color Bars) and for PAL 663.80mVP-P (75% Color Bars)...


18

All VGAs support the “official” CGA and EGA modes, so most CGA and EGA games work fine. However, compatibility can only be relied upon at the BIOS level; a VGA can be implemented without strict hardware compatibility with the older standards. This affects some CGA games in particular. There is a CGA test tool available. It was written following this ...


15

Before SCART, European TVs often had not video input at all or S-Video on 6-pin or 8-pin DIN sockets (not Mini-DIN). Cinch composite was uncommon until VCRs came out. After that the old S-Video connectors died out and it was most common for cheap TV sets to have only an antenna and one composite in, better TV sets had a SCART input very early. Component ...


15

Some laptops have built-in support for inverting the screen in one form or another; Toshiba laptops for instance have a setup menu to configure gray-scale translation and inversion, as well as a pop-up TSR and a command-line tool (VCHAD on VGA systems). If your system doesn’t have anything like this, I think your options are rather limited... As mentioned ...


12

Preface: The question sounds as if you're missing a basic understanding of interfacing and communication between different chips/systems. At the core it can't be answered without a whole course in digital electronics 101. So I can only try to give some hints to understand the various concepts presented. I've come across a couple of projects that manage to ...


11

The Electron outputs an analogue interlaced 625-line image, with a line rate of 15.625Khz. HDMI is a digital input, so cannot comprehend the Electron's analogue output. VGA is analogue but many monitors expect a line rate of 31 kHz. It's not impossible that your screen would be okay with 15.625Khz though, as that's the PAL standard, so you could at least ...


10

A direct connection is not going to work - The Gameboy's pixel clock is much too low to drive a VGA screen: GameBoy VGA Pixel clock 4 MHz 25 MHz V-Sync 60 Hz 70 Hz H-Sync 9 kHz 31 kHz So, in a nutshell, this will not work without a significant investment into capturing the GBA ...


9

Black-and-white hi-res from the 1040 STE on a VGA monitor should work with a direct connection and no tricky electronics at all (just the adapter cable) Atari VGA GND 13----X---- GND ---------4 GND Sense 4----+ +--------------2 green ...


9

It cost me something like $50 all up to connect my Electron to the TV using an RGB to SCART cable (this one from eBay) and an RGB to HDMI converter like the one pictured below: You can get this model from a bunch of different eBay sellers, under various different brand names, but they're all the same. I've tested it out with MODE 0 - MODE 6, and it seems ...


9

Your problem is mostly going to be rep movsb changing that to use rep movsw should help. If the VGA card is on a 8MHz (or 6MHz) original AT bus then the timings work like this: 3 cycles to read or write a byte 19,200 bytes being moved. 345,600 bus cycles per copy 8,000,000 / 345,600 is 23.14 copies per second. 6,000,000 / 345,600 is 17.36 copies per second. ...


8

The problem you have is that most home computers of that era output TV standard signals which VGA is not. As you've mentioned there needs to be some conversion from one standard to the other. A popular solution that I happen to use is the Gonbes GBS-8200/GBS-8220 boards. They aren't perfect and some people hate them but they are reasonably cheap and I think ...


8

The 5162, more commonly known as the IBM PC XT/286, uses a 16-bit expansion bus. Any 8-bit “ISA” VGA card should work fine (but they are rare), and most 16-bit VGA cards should work too... Ironically, the 8-bit Hercules VGA card is known to cause issues. Some 16-bit cards designed for the PC AT won’t fit in the XT/286’s case and therefore can’t be used ...


7

Some Matrox cards output composite and S-Video using the HD15 port; for example, the G450 PCI (see the TV output chapter in its manual). The adapter cable was optional though and isn’t commonly included with the graphics adapter.


7

You have three problems to overcome: Separate sync from composite video or CSYNC into H and V to get an RGBHV output. Upscale/scan double from 15 kHz to the 31 kHz that most VGA monitors accept. Separate out the audio. The $89 Ambery 15Khz RGB CGA to VGA RGBHV Converter Scaler is a device that appears to do the first two, but I have no experience with it. ...


7

You can invert the screen on a monochrome Omnibook by holding the Fn key and pressing either of the contrast up/down buttons next to the screen.


7

The other answers are good, but one specific area where VGA cards are generally incompatible with CGA is with respect to CGA's Composite mode. In the video "CGA Graphics - Not as bad as you thought!", The 8-Bit Guy demonstrates the CGA Composite mode and explains that, after about 1987 or so, new software written specifically for CGA Composite Mode became ...


7

You are seeing dot crawl which is common when sending composite video into a low quality comb filter such as in that Video to VGA Converter box. To get rid of it, you will need a better comb filter (good ones are hard to find) or avoid composite entirely by converting from the STE's analog 15 kHz RGBHV to either the 31 kHz VGA that your monitor supports, or ...


7

Quoting Wikipedia, it seems to be at least two factors: The availability of inexpensive LCD monitors has made the 5:4 aspect ratio resolution of 1280 × 1024 more popular for desktop usage during the first decade of the 21st century. (from here) The 1280 × 1024 resolution became popular because at 24 bit/px color depth it fit well into 4 megabytes of ...


7

1280x1024@24-bit fits in 4 MiB. Why wouldn't you take extra screen space? Keep in mind that games didn't usually run in 1280x1024 at the time. Back before LCDs became the dominating screen technology, you didn't care about the "native resolution" of the display - you didn't get the ugly "one pixel is stretched over two physical pixels, its neighbour only ...


6

Seems to me that the way to go would be to re-program the lookup table use by the digital to analog converter (DAC). The DAC is essentially the last component in the VGA, taking 8-bit VGA colors and deciding what each of those will represent. Thus, it affects the output from essentially all other programs, even those that write directly to the hardware. The ...


6

On some video cards, using Mode X could be used to improve the performance of copy operations that take place within video memory, but techniques which would improve performance on some cards would severely degrade it on others. In particular, mode X made it possible to copy four bytes of memory using a single byte read and a single byte write. While that ...


6

[I]s there ever a circumstance where Mode 13h is a better choice for fast scrolling DOS games over Mode X? Sure, to start with, any single pixel operation on in Mode X is slower than for Mode 13, as the desired plane needs to be set first (*1) Next, the latch-trick (*2) can only move horizontal by 4 pixels at once. So any horizontal scroller will be ...


6

For tile-based scrolling games of the "platformer" genre, it was certainly an advantage to use ModeX. This is especially true if you wanted to support slower 80286 or 80386SX CPUs with the early 8-bit VGA cards and which lacked VRAM. Here was a "triple whammy" of slow(ish) CPU, limited bus bandwidth, and limitations on shared access to the display DRAM. I ...


6

For the ST, the best option I’m aware of is to use the Atari-provided SCART cable and the OSSC; the latter will double lines etc. to produce a picture which any modern HDMI screen should be able to display. Depending on the outputs from your C64 (which may need to be modded anyway), the OSSC might not be appropriate; the RetroTINK 2X supports S-Video, ...


6

When VGA was designed and released, it had only maximum of 256 kbytes of video memory. The memory of VGA is arranged to have 32-bit interface to the VGA chip to have four byte planes in parallel. Therefore there are only 64k addresses of 32-bit video memory, and data of up to four planes can be accessed with a single CPU access. The VGA board can be ...


6

I have this monitor, which I think is a Commodore 64 monitor. Not really. And especially not for the C64. The screen was manufactured in Taiwan (*1) for/by Philips. It was widely sold as a monochrome screen to many countries. What is true is, that Commodore OEMed it ca. 1985 as 1901(*2) or later 75BM13 (*3) for/with the PC10/20/... series (*4) of IBM ...


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