On the CoCo 3 you didn't have to hit reset; there was a way to switch it in software.
Also on the CoCo 3, there was the 640 x 192 4-color "hires" mode. Way, way back - I believe published in Hot CoCo - someone figured out that using a television, and setting those 4 colors to the grayscale in the 64 color palette (black, dark grey, light grey, and white) - and with proper 4-bit pixel settings, you could get a virtual 128x192 image with colors.
Basically the same technique (called artifact colors, or artifacting) - but applied to the high-res screen of the CoCo 3.
Unfortunately - he sent it to Hot CoCo! Had he sent it to the Rainbow instead...things might have been different. You see, by sending it to that magazine, it didn't reach a large audience, so only a few people saw it, nobody much played with it, and it faded into history.
On the Rainbow side of things, there were a couple of articles about using patterns of color to create "virtual colors" - but it was geared toward the RGB monitor (CM-8), and not really the TV - and using colors, not the gray scales...
A virtually unknown "256 color" mode on the Color Computer 3 that was lost to history.
Now - this isn't the mystery 256 color mode that has been described elsewhere hiding in the GIME chip (and most people believe that it is a false rumor; but the Microware CoCo 3 prototype holds out hope) - but it is a working "hi color" mode available on the CoCo 3.
Unfortunately, today, it is only a curiosity more than anything, and it is unknown whether it could have been used back then; from what I recall, they had to use a PC to figure out the proper bit patterns for each of the colors, and that kind of processing would have been difficult at best back then.
EDIT: This really shows off what is possible with the mode:
Sure wish it had been used more back in the day. I always thought the Sierra games were a good fit.
The CoCo3 also does 50hz NTSC. Almost all US displays will take it, and it gives one a bit more time to push pixels.
One only needed a PC to derive a palette. The bit patterns are straight up binary. One byte per pixel, $0 to $ff.
No color redirection though. It is an absolute value to color display.
A palette, arranged nicely by hue and Luma takes just 1 8 bit page of RAM. Get the raw values into a PC, sort them, save off as byte data organized by huge and shade...
On 6809, 1 byte per pixel is sweet. Like the chip was made for it. If you want to abuse the stack, compiled sprites are fast.
It could be used back in the day. I did that on my CoCo in the 80's and 90's. Never developed anything big with it, but it was not difficult.
Found it one day when I did not configure the GIME chip properly. I just happened to write binary sequences... saw the rainbow, knew about artifact color on the Apple 2 and the rest was easy.
Later, with microcontrollers, I duplicated the CoCo 3 and then doubled the bit resolution and or depth. It is possible to get very full color with just monochrome bits running fast relative to the NTSC signal.
Also on the CoCo 3, there was the 640 x 192 4-color "hires" mode. Way, way back - I believe published in Hot CoCo - someone figured out that using a television, and setting those 4 colors to the grayscale in the 64 color palette (black, dark grey, light grey, and white) - and with proper 4-bit pixel settings, you could get a virtual 128x192 image with colors.
Basically the same technique (called artifact colors, or artifacting) - but applied to the high-res screen of the CoCo 3.
Unfortunately - he sent it to Hot CoCo! Had he sent it to the Rainbow instead...things might have been different. You see, by sending it to that magazine, it didn't reach a large audience, so only a few people saw it, nobody much played with it, and it faded into history.
On the Rainbow side of things, there were a couple of articles about using patterns of color to create "virtual colors" - but it was geared toward the RGB monitor (CM-8), and not really the TV - and using colors, not the gray scales...
So - what am rambling about then?
Well - long story short - this:
http://richg42.blogspot.com/2014/02/the-little-known-color-c...
A virtually unknown "256 color" mode on the Color Computer 3 that was lost to history.
Now - this isn't the mystery 256 color mode that has been described elsewhere hiding in the GIME chip (and most people believe that it is a false rumor; but the Microware CoCo 3 prototype holds out hope) - but it is a working "hi color" mode available on the CoCo 3.
Unfortunately, today, it is only a curiosity more than anything, and it is unknown whether it could have been used back then; from what I recall, they had to use a PC to figure out the proper bit patterns for each of the colors, and that kind of processing would have been difficult at best back then.
EDIT: This really shows off what is possible with the mode:
http://atariage.com/forums/blog/105/entry-6693-color-compute...