scitari

I put together a description of implementing fine horizontal scrolling in BASIC with assembly code executed during the vertical blank. This is a pretty high-level description and is directed at those learning this for the first time. A simple demo is provided with BASIC code and assembly code explained. An ATR file is provided. Fine horizontal scrolling has a lot of moving parts and can be hard to understand for those who have not yet mastered it. I hope someone finds this take on it helpful. Comments welcome! Fine horizontal scrolling post from Atari Projects

Right! Thanks!

Thanks for giving it a try. I have been testing this code in Altirra with Altirra BASIC and cold boots in between tests.

I understand the basics of how DLIs work and how to implement them in BASIC with assembly routines. However, I have found them to be very fussy and have come to believe maybe I missing something important. The DLI BASIC code below successfully draws the screen with four different shades of blue. The assembly code for setting the background color registers comes from listing 8.2 of Compute's Second Book of Atari. It reads from a table of colors stored in page 4 of memory. Here are some weird observations I don't understand and need your help with. First, if I remove the POKE 752,1 from line 1000 I get a black screen. This seems odd. Why? Second, if I move lines 5000+ up between lines 2000+ and 3000+ the colors are shifted down by six lines. Why would that matter? Thanks for any insight you can provide! The code is below. I have also attached it as a .txt file and with the BASIC code in an ATR. 1000 GRAPHICS 1+16:POKE 752,1:PRINT " " 1010 DIM DLI$(35) 1020 DL=PEEK(560)+PEEK(561)*256 2000 REM read in assembly code to modify graphics 2010 FOR I=1 TO 35:READ X:DLI$(I)=CHR$(X):NEXT I 2020 DATA 72,152,72,172,0,4,185,2,4,141,10,212 2030 DATA 141,24,208,238,0,4,173,0,4,205,1,4 2040 DATA 144,5,169,0,141,0,4,104,168,104,64 3000 REM modify display list for interrupt 3010 FOR I=2 TO 3:POKE DL+I,PEEK(DL+I)+128:NEXT I 3020 FOR I=6 TO 27:POKE DL+I,PEEK(DL+I)+128:NEXT I 4000 REM point to DLI in memory and enable interrupt 4010 DLIADR=ADR(DLI$) 4020 DLIHI=INT(DLIADR/256):DLILO=(DLIADR-DLIHI*256) 4030 POKE 512,DLILO:POKE 513,DLIHI 4040 POKE 54286,128+64 5000 REM read background color data to page 4 5010 POKE 1024,0:POKE 1025,24 5020 FOR I=0 TO 23:READ X:POKE 1026+I,X:NEXT I 5030 DATA 112,112,112,112,112,112,114,114,114,114,114,114 5040 DATA 116,116,116,116,116,116,118,118,118,118,118,118 10000 GOTO 10000 DLIweird.atr DLIweird.txt

Yes, I figured out that Disk 1 Side 2 is the boot disk. Go figure!

There are now 150 projects completed and posted to the Atari Projects website!

Boot from side 2! Go figure! Thanks for getting me up to speed. Looking forward to playing.

I would like to play Nox on original hardware (Apple IIe platinum) and have copied the disk images to 5.25 floppies using ProDOS. However, the disks won't boot. I get a "Unable to load ProDOS" message when booting from floppy. I get the same message when trying to boot from my Floppy Emu. I am relatively new to Apple II so maybe I missing something simple. Any ideas? Many thanks!

Note that the Magic Dump II binary is not available on Atarimania.

The hardware I own is listed in my profile. Generally, I have a few of each 8-bit computer along with a number of peripherals.

This would be so freaking cool! Count me in!

Count me in!

The bottom of the joystick doesn't get enough love.

Please DM me the PWD. Thanks!

Kudos to the team! Very nice to see this amazing device featured on Hackaday.