How does text mode works on PC compatibles? How similar are those still done today on modern computers? How similar was it to, e.g. NES BG graphics?
The only information I found is that the orignal IMB PC had a fixed 80x25 character resolution and was monochrome by default. You could buy expensive extention carts to get colour and/or higher resolution graphics, but the PC was already natively handling colour internally. I think it has 16 colours (4 shades of gray and 12 full hues colours at 2 level of brightness). It seems to use a tile system which allows 256 tiles and a background and foreground color for each of them but the background can only be among the "dark" set of 8 colours. (The extra bit is used for blinking, which is very stupid since that effect could be done in software.)
As such each caracter is definied as a "word", 1 byte for attribute and 1 byte for character. But how does the program mantain compatibility if the terminal is larger than 80x25 ? Do they allow to modify tiles like NES does with CHR-RAM ? But if you don't know what is the size of the characters in the first place, how is it done ?
Is there somewhere a comprehensive list of graphic modes for PCs ? It seems I cannot find any. My understanding is that in bitmap modes, the first PCs could only draw CGA, and thus be less colorful than text mode where all 16 colours could be used anywhere, but I'm not even sure about that. Eventually, 16-colour, 256 colour and 65536 colour and 32k colour graphical mode became common.
The only information I found is that the orignal IMB PC had a fixed 80x25 character resolution and was monochrome by default. You could buy expensive extention carts to get colour and/or higher resolution graphics, but the PC was already natively handling colour internally. I think it has 16 colours (4 shades of gray and 12 full hues colours at 2 level of brightness). It seems to use a tile system which allows 256 tiles and a background and foreground color for each of them but the background can only be among the "dark" set of 8 colours. (The extra bit is used for blinking, which is very stupid since that effect could be done in software.)
As such each caracter is definied as a "word", 1 byte for attribute and 1 byte for character. But how does the program mantain compatibility if the terminal is larger than 80x25 ? Do they allow to modify tiles like NES does with CHR-RAM ? But if you don't know what is the size of the characters in the first place, how is it done ?
Is there somewhere a comprehensive list of graphic modes for PCs ? It seems I cannot find any. My understanding is that in bitmap modes, the first PCs could only draw CGA, and thus be less colorful than text mode where all 16 colours could be used anywhere, but I'm not even sure about that. Eventually, 16-colour, 256 colour and 65536 colour and 32k colour graphical mode became common.