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Everything posted by scitari

  1. 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
  2. Thanks for giving it a try. I have been testing this code in Altirra with Altirra BASIC and cold boots in between tests.
  3. 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
  4. Yes, I figured out that Disk 1 Side 2 is the boot disk. Go figure!
  5. There are now 150 projects completed and posted to the Atari Projects website!
  6. Boot from side 2! Go figure! Thanks for getting me up to speed. Looking forward to playing.
  7. 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!
  8. Note that the Magic Dump II binary is not available on Atarimania.
  9. 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.
  10. This would be so freaking cool! Count me in!
  11. The bottom of the joystick doesn't get enough love.
  12. Kudos to the team! Very nice to see this amazing device featured on Hackaday.
  13. I used to get boxes of Atari stuff for $10-$20 each in the early 2000s. So glad I put my collection together then! I miss those days....
  14. There is a 16K ATR 8000 for sale on Goodwill right now. https://www.shopgoodwill.com/Item/104793886
  15. I have participated in several Atari 8-bit computer zooms over the summer. So much fun. Everyone talked about what they were doing with the Atari and some even did some live demos of projects or games. Find a group of like-minded folks and send out an invite! Less than 10 people usually works better than a big group.
  16. Thank you Curt for all your hard work to preserve Atari history. I learned so much from you. RIP.
  17. Welcome to Atari! You will be glad you came. I maintain a website with over 125 fun hardware, software, and programming projects for the Atari 8-bit computers. Most of the projects can be completed in less than an hour, and each comes with step-by-step instructions. It is called Atari Projects. I hope you find it useful!
  18. I have an ATR 8000 (64K) and recently purchased a new old-stock 5.25" IBM 360K drive for it. The drive spins but couldn't get CPM to load. I think I need to boil the belt to get the timing right. On my list of things to do this summer. Would love to get a few more standard drives for this. Am interested in what others use as standard drives can be a bit hard to find used and working.
  19. I got back into the hobby a few years ago. I have been documenting projects as I complete them. Welcome back! My personal favorite is the Atari 800, 810, and 820 combo. I have all the others but the 800 is my first love. Have this set on my desk right now. My favorite games are Sea Dragon, Donkey Kong, Joust, and Qix.
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