St LOW bit planar structure

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hylst
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St LOW bit planar structure

Postby hylst » Tue Aug 13, 2013 6:52 pm

Could anyone remind me, too casual coder, for sure of the bit planar structure of the screen in ST LOW rez ?

32000 bytes
320 rows x 200 lines
4 planes that regroup 16 pixels each time like this (4 words) ?
colour number coded in a nibble separated in that 4 planes according pixe number


Plane 1 Plane 2 Plane 3 Plane 4 -> next 16 pixel same structure until 64000/8 time
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
0 1 2 3 4 5 6 7 8 9 A B C D E F 0 1 2 3 4 5 6 7 8 9 A B C D E F 0 1 2 3 4 5 6 7 8 9 A B C D E F 0 1 2 3 4 5 6 7 8 9 A B C D E F <- the pixel number
(msb of each plane = first pixel of the block ? (talking from the left on screen))

Setting the 3rd pixel at colour 1 would be setting 0010000000000000 on plane 1 ?
Setting the 14th pixel at colour 4 would be setting 0000000000000100 on plane 3 ?
Setting to 1 the same bit (pixel) on plane 2 and 4 would set it's colour to 0101 = 5 ? (colour coded at $ff8240 + 2*5 ?)


Thank you 4 your help !
Falcon CT60 +CENTRAM14 - 520 STE 4M - 1040 STf
Let's visit my Personal website http://hylst.t15.org !
The new website of my productions (French for the moment)

FedePede04
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Re: St LOW bit planar structure

Postby FedePede04 » Tue Aug 13, 2013 7:29 pm

hylst wrote:Could anyone remind me, too casual coder, for sure of the bit planar structure of the screen in ST LOW rez ?

32000 bytes
320 rows x 200 lines
4 planes that regroup 16 pixels each time like this (4 words) ?
colour number coded in a nibble separated in that 4 planes according pixe number


Plane 1 Plane 2 Plane 3 Plane 4 -> next 16 pixel same structure until 64000/8 time
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
0 1 2 3 4 5 6 7 8 9 A B C D E F 0 1 2 3 4 5 6 7 8 9 A B C D E F 0 1 2 3 4 5 6 7 8 9 A B C D E F 0 1 2 3 4 5 6 7 8 9 A B C D E F <- the pixel number
(msb of each plane = first pixel of the block ? (talking from the left on screen))

Setting the 3rd pixel at colour 1 would be setting 0010000000000000 on plane 1 ?
Setting the 14th pixel at colour 4 would be setting 0000000000000100 on plane 3 ?
Setting to 1 the same bit (pixel) on plane 2 and 4 would set it's colour to 0101 = 5 ? (colour coded at $ff8240 + 2*5 ?)


Thank you 4 your help !


hi
it look right the about

first word the 16 first pixel in bitplane 1
second word 16 first pixel in bitplane 2
third word the 16 first pixel in bitplane 3
fourth word 16 first pixel in bitplane 4
fifth word the next 16 pixel in bitplane 1
and so on :)

every line conatin 160 bytes

/Peter
Atari will rule the world, long after man has disappeared

sometime my English is a little weird, Google translate is my best friend :)

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hylst
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Re: St LOW bit planar structure

Postby hylst » Tue Aug 13, 2013 9:11 pm

Thank you. And what about, in each word, the match between the pixel number, and the value between most and least significant bit ?
Does MSB really match with the first pixel at the left, graphically talking, in the bloc of the 16 pixels ?

Just 2 be sure, i'm not that sure according to what my plot asm rout try does.

by the way, is there any text on internet which deals with asm call in gfa, what can be passed, how, and in assembly, what must be saved / checked ?
Falcon CT60 +CENTRAM14 - 520 STE 4M - 1040 STf
Let's visit my Personal website http://hylst.t15.org !
The new website of my productions (French for the moment)

FedePede04
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Re: St LOW bit planar structure

Postby FedePede04 » Tue Aug 13, 2013 9:49 pm

i am also a little rusty in atari code, but i am nearly 100% sure this is 3 pixel from the left.
%0010000000000000

sorry i can't help you with the GFA basic, but i have forgot all, but i know the are some on this site that should be able to help you.
/Peter

hylst wrote:Thank you. And what about, in each word, the match between the pixel number, and the value between most and least significant bit ?
Does MSB really match with the first pixel at the left, graphically talking, in the bloc of the 16 pixels ?

Just 2 be sure, i'm not that sure according to what my plot asm rout try does.

by the way, is there any text on internet which deals with asm call in gfa, what can be passed, how, and in assembly, what must be saved / checked ?
Atari will rule the world, long after man has disappeared

sometime my English is a little weird, Google translate is my best friend :)

User avatar
hylst
Obsessive compulsive Atari behavior
Obsessive compulsive Atari behavior
Posts: 133
Joined: Wed Apr 27, 2011 6:22 pm
Location: France : Strasbourg
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Re: St LOW bit planar structure

Postby hylst » Tue Aug 13, 2013 9:56 pm

Thanks FP ! =)
Falcon CT60 +CENTRAM14 - 520 STE 4M - 1040 STf
Let's visit my Personal website http://hylst.t15.org !
The new website of my productions (French for the moment)


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