Posted By
Litwr
on 2022-10-27
04:59:20
|  Yet another Basic error?
I have accidentally found a diiference in implementations of the DRAW command. For the Plus/4 DRAW0 just changes the color source but for the C128 it also puts a pixel for the current coordinates. I don't understand what is better. So it is a question which Basic has an error.
BTW I also found out that fp-routines for the C128 and C+4 produce slightly different results.
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Posted By
MMS
on 2022-10-27
11:46:05
 | Re: Yet another Basic error?
Nice find!
My idea: the CBM v3.5 and the V7.0 should support the turtle graphics in some ways.
So, changing just the pen color does not mean, you want to draw a pixel, you did not give such a command.
So it should be an unintentional pixel drawing in C128, and seems you cannot circumvent it.
I think it should be a bug on C128, while C16 does it properly.
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Posted By
SVS
on 2022-10-28
15:04:42
 | Re: Yet another Basic error?
In C16/Plus4 BASIC, the DRAW command prints a pixel only when the x,y coordinates are supplied and TO keyword is missing.
Examples:
DRAW ,x,y will print a pixel at x,y coordinates.
DRAW z,x,y will print a pixel at x,y coordinates.
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Posted By
Litwr
on 2022-10-29
01:13:37
| Re: Yet another Basic error?
We can also say that this is Basic 7.0 incompatibility with Basic 3.5 - however it interesting why did they change the DRAW algorithm?
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Posted By
siz
on 2022-11-01
04:35:13
| Re: Yet another Basic error?
> why did they change the DRAW algorithm?
IMHO they didn't. They are completely different implementations. BASIC 3.5 of the 264 series is based on BASIC 2.0 implemented by Commodore and BASIC 7.0 of the Commodore 128 is made by Microsoft.
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Posted By
Lavina
on 2022-11-01
06:59:14
 | Re: Yet another Basic error?
Well, all versions of Commodore Basic are based on Microsoft's Basic language.
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