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1

The question mentions “early PCs” that generated a TV-compatible RF signal and “the color TVs of those days”. This would be a period spanning from at around mid-to-late 1970s to mid-1980s. The computer systems in question would be microcomputers aimed at the home market. By the late 1970s, new TV sets were already transistor-based and IC-based designs. ...


20

Many TV designs up into the 1970s were so called live chassis designs, which used one leg of the mains input as a reference ground. This saved materials and weight - given some early color TVs used 200+ watts at 100% duty cycle, you would have needed a rather bulky and heavy transformer, given that PSMPS technology was not really mature for consumer devices ...


10

TV manufacturers didn't have a single, obvious RGB connection standard to implement. Physically, there was SCART (with competing European and Japanese pinouts), RCA, DE-9, and various manufacturer-specific DIN plugs to choose from. Then you have the various electrical signals to send over them such as RGBS, RGsB, RGBHV, YPrPb, digital RGBI, etc. And VCRs ...


63

When colour television broadcasts began (1960s, in the UK; perhaps a little earlier in North America?) there weren't any local devices that customers might want to use. Broadcast TV was the only source of images that any home user could imagine. Adding extra circuitry to handle separated R, G, B and sync inputs (with appropriate protections against overload ...


21

Early colour TVs predated VCRs and home computers by many years. Even if it did not cost much, adding an RGB input would still be a cost for something that no one would use. However, it would have been more complex and expensive than you might expect today.


3

Somewhat of a side note - The Atari 8 bit series (400 | 800 | 65XE | 130XE - 6502 based, running at 2Mhz), normally displayed 40 characters per line on a color TV. There are some terminal type programs that horizontally scroll the 40 line display to get a virtual 80 character per line terminal, or use a 3 by 5 font (with 1 pixel between characters) (from ...


9

The monitor is physically attached - part of the unit There's no video port. You have to use the built-in monitor. As such, Commodore simply chose a monitor fit for 80 columns. That wasn't hard, since NTSC monochrome composite video has unlimited horizontal resolution. And 7 vertical scan lines per character form (+1 scan line for spacing) is enough to ...


23

Use of TV as monitor is the reason for these low resolutions. The issue is that the color resolution of TV is very low. While B&W TV could resolve pixel small enough for ~400 to ~600 pixels, color resolution was much much lower, barely around 200 pixels. Some computers exploited this, such as Apple II and CGA/composite. It also shows the limits of that ...


12

Space on a chip die was very limited - you couldn't just put an unlimited amount of functionality into one chip. If you have a closer look at video chips used in 8 bit computers, they either feature an 80 column mode (PET, Amstrad CPC, later Apple IIs, C128 VDC) or a lot of game related functionality like sprites, hardware scrolling, raster interrupts etc. (...


50

One reason was likely that the VIC-20 and C64 did not have their own displays, but were designed to be connected to a television set. The interface between the computer and the television was not sufficient to display 80 column text (it would have been almost unreadable). However, the PET had its own integrated display so it did not have this limitation, and ...


0

Afaik the RGB port on the electron is the same as the one on the BBC micro. This is digital RGB with composite sync at TTL levels. It also provides a handy 5V supply. This can be adapted to RGB Scart with a few resistors to lower the signal levels and create the trigger voltages to tell the TV to use RGB scart mode. There is plenty of room in the shell of ...


4

Early models of the CDTV had OCS chips and later ones could have a mix of OCS and ECS, and some late models could have the full ECS chipset. It could also be upgraded to ECS by the user. The CDTV II that you link to was never released though so that's probably not what you have unless you own a prototype. But even if you have the full ECS chipset it didn’t ...


3

RGBI to RGB only needs a couple of diodes and resistors, see e.g. here, and that will work with VGA-RGB. I am not aware off-the-shelf ones for that are available, OTOH they are not exactly difficult to make yourself. I have no idea what @mnem means by "RGBA", usually this is an abbreviation for red-green-blue-alpha, and refers to how image data is ...


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