Jump to content
Have You Played Atari Today?
2600|5200|7800|Lynx|Jaguar|Forums|Store  

Thelen

Members
 View Profile  See their activity

  • Content Count

    543

  • Joined

  • Last visited

Posts posted by Thelen

  5. Posted

    off course that's possible. let's assume your cartridge is on $8000-9fff. then if you say LDA $AA- STA $8000, then the r/w line on the cartport will be set, and the data willen appear there.

     

    but this will also when you say $8001 and 8002 etc..... so you'll have to mask out the adres you want to with some and/nand ports.

     

    Thelen

  14. Posted

    I Have used many time the CMP and BPL/BMI function, and this time i noticed something strange, and now i know why my other programs did sometimes strange things

     

    loop lda tmp1

    cmp #0 ; als tmp1 groter dan tmp2 is gaat ie naar groter

    bpl groter

    lda #1

    sta tmp3

    jmp loop

    groter

    lda #2

    sta tmp3

    jmp loop

     

    when i fill in for tmp1 #10 then it jumps to GROTER...but this works until the value $DC is given (if i remember correct), and above this value it won't work anymore, so it won't jump to GROTER.....this is so strange...Why is this ?

     

    thanks, Thelen

  16. Posted

    That's a good one. I had the same problem that i need to know on what character the player is. I used 2 bytes, playerH and playerL and when then player moved 4 positions to the right playerL would increase. when it goes down, playerL would increase with 40. PlayerL and playerH are the low/high bytes of the adress where the character is in the video memory.

     

    indeed, with zero page you can get the character where it's standing on back.

     

    CHECPOS

    STY $B3; high byte

    STX $B2; low byte

    STY TMPS

    LDY #0

    LDA ($B2),y ; a holds the number of the character

    LDY TMPS

    RTS

     

    I have this as a sub-routine, because it's very easy to use for all kind of things to check in the memory.

     

    Thelen

  18. Posted

    yes, starting with the 5200 is a much better idea. But I suggest to start with programming for the atari 8 bit computer line (xl/xe) there is plenty of documentation about, and once you understand how the system works, you can program also for the 5200. The 5200 is a stripped down version of an atari 8 bit.

     

    All things should work with win XP, but you can't see everything....I would recommend win 98 or 95.....or dos, but i think working in windows is easier.

     

    i have learned almost everything from the book 'atari graphics and arcade game design' and a LOT of trying things......

    it's easier if you know before you start what LDA/STA/CMP etc. does....

     

    that book and other intresting books are online at the

     

    www.atariarchives.org

     

     

    I think it's strange, there is no real tutorial or some examples about programming the 7800....a display list list, a example with some text etc..Even the 2600 is better documented, but programming the 7800 wouldn't be so difficult as the 2600..

     

    Thelen

  23. Posted

    You don''t need the óriginal developpers hardware' to do something with the 7800. All you need is 6502 asm knowledge (which sound more difficult then it actually is) and some knowledge about the 7800 (video)hardware.

     

    I know 6502 and program things for the atari 8 bit computers, and i read a few day's ago information about the 7800.....but there isn't enough documentation about the 7800 maria video chip for me........

     

    Thelen

AtariAge
Forums
Store
General
Follow AtariAge

Copyright ©1998-2021 AtariAge

×
×
  • Create New...