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The three official video modes described on the CPC wiki are all bitmap modes, and this page mentions that the "screen is bitmapped. You must draw/erase your own sprites and text."

So what was the standard way of generating text on the screen, scrolling it, and so on? Were there ROM routines that most programs used, or was it just left up to the individual programs to do it with their own code? Was there any special hardware support to help with text and, particularly, scrolling? Were there standard text "modes," used by most programs and, if so, what were they?

Also, since the CPC was normally sold with a monitor, were text modes with more than 40 columns per line frequently used? I am guessing that with a monitor (particularly the monochrome one) the usual color vs. resolution issues on TVs could be avoided and so 64, 71 or even 80 column modes might be common, especially for business software.

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All text is painted as bitmaps.

The highest-resolution built-in mode is 640x200 pixels, so that provides an 80x25 text mode. 80-column modes were used in business software (e.g. DBase II) and even in the CP/M 2.2 and 3.0 OS.

The CPC uses a CRTC6845, which is wired up atypically to create linear scan lines but nevertheless can still hardware scroll in multiples of 8 lines. So a hardware text scroll is available.

Firmware routines are provided to establish text windows, move the cursor, set colours, optionally set a custom font, and to paint text. So they're there if you want to use them.

The disk-based CPCs came with CP/M, in which it provides software with the same control codes as a Zenith Z19.

On clarity, I grabbed the following from a Youtube video demonstrating the 6128 hardware showing 80-column text on a real CPC:

enter image description here

So you can see that the screen is very sharp at that resolution; the colour screen was received just as sharp a signal as the green screen shown, being a full RGB connection. See @rwallace's comment re: dot pitch; the best video evidence I could find is unfortunately a glancing shot:

enter image description here

Though I think that at least establishes the absence of most of the standard computer-with-a-TV artefacts, at least for the era when only France could boast wide adoption of Peritel/SCART.

  • 'the colour screen was just as sharp as the green screen shown, being a full RGB connection' - are you sure? I was given to understand that while the RGB connection helped, the color screen was a low-cost color TV tube whose dot pitch was still not fine enough to make 80 column text usable. – rwallace Aug 2 at 9:58
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    @rwallace see around 04:50 in youtu.be/ndkQdDWGMdM ; that Youtube video has some saturation issues but it's the best I've so far found. I'll keep looking. – Tommy Aug 2 at 11:53
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    @rwallace - the colour screen was okay for 80 column text. Not super crisp, but good enough for word processing. It was my first computer, and saw me through university essays. – scruss Aug 2 at 23:16

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