fastbasic DLI colors

[eflake]

When I run this test, the first top two lines of gr.0 is the normal background, it seems the first line starts at 6 - dpeek(560)+6, 130..  when I try line 5, nothing is displayed not even the print statement. What am I not understanding?  Thanks. Running the .atr version 4.5 and altirra 3.90 XL/XE mode

 

DATA COLORS() BYTE = $FF

DLI SET D2 = COLORS INTO $D01A,
DLI         = $00 WSYNC INTO $D018,
DLI         = $BA WSYNC INTO $D018,
DLI         = $BB WSYNC INTO $D018,
DLI         = $BC WSYNC INTO $D018,
DLI         = $BD WSYNC INTO $D018,
DLI         = $BE WSYNC INTO $D018,
DLI         = $BF WSYNC INTO $D018
 

' SETUPS SCREEN
GRAPHICS 0
' ADDS DLI AT THREE LINES:
POKE DPEEK(560) + 6, 130

' ACTIVATE DLI
DLI D2

 

'WAIT KEY

GET K

DLI

..

 

 

[TGB1718]

 

45 minutes ago, eflake said:

when I try line 5, nothing is displayed not even the print statement.

Display List, first 6 bytes are

 

$70    8 Blank Lines

$70    8 Blank lines

$70    8 Blank line

$42    LMS Mode 2

$40    Low byte of screen address

$BC    High Byte of screen address

$02

etc.

.

so when you poke into line 5 you are changing the high byte of the screen address

if you wanted the DLI on the first line you need to POKE PEEK(560)+3,$C2

$C2=mode 2 line+LMS+DLI

 

The print statement is going the the screen @560/561 but the display list is now showing some other area of memory, thats why you don't see anything

Edited March 14, 2021 by TGB1718

[dmsc]

Hi!

Quote

When I run this test, the first top two lines of gr.0 is the normal background, it seems the first line starts at 6 - dpeek(560)+6, 130..  when I try line 5, nothing is displayed not even the print statement. What am I not understanding?  Thanks. Running the .atr version 4.5 and altirra 3.90 XL/XE mode

You need to understand how Display-Lists work.

 

The DLI fires in the next line of the display-list where it is maked. So, to have a DLI in line two, you need to mark line 1. But line 1 is special, it is a LMS (load-memory-scan-counter) operation so it takes 3 bytes instead of one, and has a value of 64 more than the standard. This means that you need to use POKE DPEEK(560) + 3, 130+64

 

There are a lot of o online resources that explain display-lists in the Atari.

 

Have Fun!

 

 

Edited March 14, 2021 by dmsc
fixed example

[TGB1718]

27 minutes ago, dmsc said:

This means that you need to use POKE DPEEK(560) + 6, 130+64

no, that location is the 7th line of the display list, the first display line instruction starts at byte 4 

if you poke $C2 into byte 7, it will need an address following it as I have shown in my explanation $C2=mode 2 line+LMS+DLI

 

[dmsc]

Hi!

33 minutes ago, TGB1718 said:

no, that location is the 7th line of the display list, the first display line instruction starts at byte 4 

if you poke $C2 into byte 7, it will need an address following it as I have shown in my explanation $C2=mode 2 line+LMS+DLI

 

You are right, of course, a copy-paste problem  

 

it was: POKE DPEEK(560) + 3, 130+64

 

Have Fun!

[eflake]

My main question is, why do i get this at the very top? I want to color the top of the display -  or is that the point of all of this 'continue on my google pilgrimage?'

 

Doing this I still see the same image as the below link:

POKE PEEK(560)+3,$C2

POKE PEEK(560)+3,$C2

 

DLI - Image on Pasteboard

[TGB1718]

There's an excellent technical description for all things ANTIC and CTIA/GTIA in the 400-800 Technical Reference Notes

 

Section II (Pages 483 onwards) 

 

Edited March 14, 2021 by TGB1718

[TGB1718]

You are using the DLI on the first display line, so it takes effect on next line, so the line the DLI acts on will not change

you could just change the last blank line to $F0 POKE 560+2,$f0

[eflake]

Thanks, it helps.