Cyningstan
curtmackInspired by an offhand comment Alice (@foone) made earlier today: the CGA iceberg
Alice Averlong🏳️⚧️@curtmack awesome!
Jacob Alexander Tice
Alex
gloriouscow
LP still can't spell Ainmhícon@gloriouscow @curtmack @foone somewhere in the mantle lies the Area 5150 demo
(which I guess puts https://int10h.org/blog/2015/04/cga-in-1024-colors-new-mode-illustrated/ "only" on the sea floor)
Area 5150 sounds cool
@gloriouscow @curtmack @foone it is! https://www.youtube.com/watch?v=fWDxdoRTZPc , and see the description for the commitment to graphics wizardry, or it runs correctly in martypc and is in the default loader menu it boots into
Area 5150 by CRTC & Hornet (Party Version) / IBM PC+CGA Demo, Hardware Capture
Visiting Area 5150: Investigating a PC Demo | VCFMW 19 (2024)
the Hearth 
@Hearth @foone
- Mode 5 is an undocumented mode that disables the color burst while also combining the two mode 4 palettes (cyan/red/white, instead of green/red/yellow or cyan/magenta/white). It also respects the palette intensity bit, so two palettes total.
- Graphics in mode 4 get their color because the two per-pixel bits and the two palette select bits each correspond to one of the RGBI bits for that pixel. So they aren't "palettes" in the traditional sense.
- Mode 5 is an undocumented mode that disables the color burst while also combining the two mode 4 palettes (cyan/red/white, instead of green/red/yellow or cyan/magenta/white). It also respects the palette intensity bit, so two palettes total.
- Graphics in mode 4 get their color because the two per-pixel bits and the two palette select bits each correspond to one of the RGBI bits for that pixel. So they aren't "palettes" in the traditional sense.
Incident Creator ❎@curtmack
And on the Amstrad PC1512/1640 there were 4 writable colour planes in 640x200 mode (RGBI) that you could selectively write enable with a plane register. By default all planes, which were all in the same CGI Mono memory space, were enabled for black & white. Oh yes. Writing graphics drivers was super fun back then.
@foone
And on the Amstrad PC1512/1640 there were 4 writable colour planes in 640x200 mode (RGBI) that you could selectively write enable with a plane register. By default all planes, which were all in the same CGI Mono memory space, were enabled for black & white. Oh yes. Writing graphics drivers was super fun back then.
@foone
MegatronicThronBanks@megatronicthronbanks There's a special circuit on IBM CGA cards so they render low-intensity yellow as brown. Some clones lacked this circuit, so they would display a darker yellow instead. Also, since RGBI was a digital signal, RGBI monitors needed their own brown circuit.
@curtmack @megatronicthronbanks
this might blow your mind but the brown circuit is not on the CGA card.
it's in the monitor
@gloriouscow I knew there was *a* brown circuit in the monitor, but wouldn't the card have its own brown circuit for composite out? Or does composite out just use dark yellow?
@curtmack It was only added to the digital RGBI 5153 monitor, so you wouldn't see brown in composite mode.
dark yellow kind of looks like pea soup or baby vomit
@curtmack people with memories of CGA games running on a composite monitor just lived in an alternate timeline than the rest of us
@gloriouscow
Cool!
My earliest computer memories are of VGA and Wolfenstein 3D, so all my knowledge of "real" CGA comes from the Internet. The closest I ever got was playing around with ZZT as a teenager and learning why there were 16 text colors but only 8 background colors (because ZZT forces blink mode).
Cool!
My earliest computer memories are of VGA and Wolfenstein 3D, so all my knowledge of "real" CGA comes from the Internet. The closest I ever got was playing around with ZZT as a teenager and learning why there were 16 text colors but only 8 background colors (because ZZT forces blink mode).
Sooo many compromises, because hardware was expensive and things weren't that miniaturised yet!
Jonathan Harker