Thomson TO7 - SCREEN (X,Y)

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jonesypeter
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Thomson TO7 - SCREEN (X,Y)

Message par jonesypeter »

Greetings,

My understanding is that the SCREEN (X,Y) does not work with characters which have been defined with DEFR$. For example the following code returns 65, and 0.

Is there any alternative to SCREEN(x,y) for defined characters, or can I tell the pen and paper at any character space. Is the only option to use the POINT (X,Y) command? Thanks

Code : Tout sélectionner

10 CLEAR ,,2
20 DEFGR$(1)=8,28,62,127,62,28,0,0
30 CLS
40 LOCATE 2,4
50 PRINT "A";gr$(1)
60 LOCATE 0,6
70 PRINT SCREEN(2,4);" ";SCREEN (3,4)
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Daniel
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Re: Thomson TO7 - SCREEN (X,Y)

Message par Daniel »

screen_to770.png
screen_to770.png (148.57 Kio) Consulté 1262 fois

You can select the foreground and background color before printing any character with the COLOR statement.
The POINT function can only retrieve one pixel color, not all the character colors.

Unlike less advanced computers, Thomson computers do not have a character mode. They only have a graphic mode. This is why it is difficult to search for characters in video memory. You have to compare the eight bytes of the displayed character with the eight bytes of each character in the standard character table. This is extremely long. It should be avoided.

It's the same for the colors. There are eight segments of eight pixels per character, each segment has a background color and a shape color, so a character can contain sixteen different colors.
Daniel
L'obstacle augmente mon ardeur.
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jonesypeter
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Re: Thomson TO7 - SCREEN (X,Y)

Message par jonesypeter »

Thanks Daniel,

That's very clear. If I plan my graphics carefully along with use of Pen and Paper I should be able to use the POINT Command.

The ability to have different colours in each 8x1 pixel area is very impressive. Especially for an 8-bit machine.
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__sam__
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Re: Thomson TO7 - SCREEN (X,Y)

Message par __sam__ »

Actually you can draw almost photo-realistic pictures on thomson (see here or there or even this demo).
Samuel.
A500 Vampire V2+ ^8^, A1200 (030@50mhz/fpu/64mb/cf 8go),
A500 GVP530(MMU/FPU) h.s., R-Pi, TO9, TO8D, TO8.Démos
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