Search found 8 matches

by siudym
Sat Jan 14, 2023 11:25 am
Forum: Demos
Topic: My First two games (test,demo) writen in ASM.
Replies: 1
Views: 5855

My First two games (test,demo) writen in ASM.

My beginnings in SMD/GEN ASM (ASM68K). Simple Untitled demos of platform games, mixed graphics of mine+other games, music by me. https://www.youtube.com/watch?v=zwvWTNM1U9Q https://www.youtube.com/watch?v=XUKBS3SV-JU https://i.postimg.cc/NGdc6hN4/212121.jpg . https://i.postimg.cc/ZK0hjf2h/Bez-tytu-u...
by siudym
Fri Nov 04, 2022 10:56 am
Forum: Megadrive/Genesis
Topic: Enable / Disable vertical interrupts in Mode Register 2
Replies: 3
Views: 8596

Re: Enable / Disable vertical interrupts in Mode Register 2

Thanks, I need to analyze this. Here is an example in the attachment, the game does not work on a real console, but it works on any emulator. Before loading the gameplay screen of the game, I have to disable VBLANK (update function of collected items on the screen - I turned off VBL "for safety" so ...
by siudym
Thu Nov 03, 2022 6:42 pm
Forum: Megadrive/Genesis
Topic: Enable / Disable vertical interrupts in Mode Register 2
Replies: 3
Views: 8596

Enable / Disable vertical interrupts in Mode Register 2

Are there any restrictions on disabling and re-enabling vertical interrupts - i.e. BIT5 in Mode Register 2? In the code, I had to turn off VBLANK IRQ and then turn it on - everything worked fine on emulators, but the code running on real hardware did not do correctly set bit5 on register 2 ... (gene...
by siudym
Wed Nov 02, 2022 10:06 am
Forum: Megadrive/Genesis
Topic: Help in understanding 68K indexed indirect addressing
Replies: 9
Views: 6178

Re: Help in understanding 68K indexed indirect addressing

I use ASM68K (SN 68k version 2.53).

The earlier code also works, the only thing missing was to copy (A0) to A0:

LEA LEV_TBL(PC),A0
ASL.L #2,D0
ADD.L D0,A0
MOVE.L (A0),A0
JMP (A0)

But of course, this solution is more correct:
MOVE.L LEV_TBL(PC),A0
ASL.W #2,D0
MOVE.L 0(A0,D0.W),A0
JMP (A0)
by siudym
Tue Nov 01, 2022 10:17 am
Forum: Megadrive/Genesis
Topic: Help in understanding 68K indexed indirect addressing
Replies: 9
Views: 6178

Re: Help in understanding 68K indexed indirect addressing

Actually: D I just noticed it ... Yes, everything goes beyond 64KB that is 24BIT ROM addressing.

Now works, second code have error:

Error : Missing or misplaced ')' in operand move.l lev_tbl(d0.l,pc),a0
by siudym
Tue Nov 01, 2022 9:47 am
Forum: Megadrive/Genesis
Topic: Help in understanding 68K indexed indirect addressing
Replies: 9
Views: 6178

Re: Help in understanding 68K indexed indirect addressing

It still doesn't work. I changed (A0,D0,L) because I probably need to add Index as L instead of W for 24bit ROM addressing? But it doesn't change anything. Here is an example code 6502 and Z80 that I have with exactly the same use. The 6502 was very simple, the Z80 had some combination problems at t...
by siudym
Mon Oct 31, 2022 8:19 am
Forum: Megadrive/Genesis
Topic: Help in understanding 68K indexed indirect addressing
Replies: 9
Views: 6178

Re: Help in understanding 68K indexed indirect addressing

Thanks. I have another question. Because I don't know if I'm doing it right. I would like to load A0 LoadLEVxxx address from TABLE which will be indexed with level number and jump to LABEL using JMP (A0). Unfortunately, while the jump under LoadLEV000 works (without the index), the indexed LEV does ...
by siudym
Sat Oct 29, 2022 10:48 am
Forum: Megadrive/Genesis
Topic: Help in understanding 68K indexed indirect addressing
Replies: 9
Views: 6178

Help in understanding 68K indexed indirect addressing

I go back to 68000 assembler and have a question about indexing. Sample code in Z80,6502 and its equivalent from 68K: I need help with 68K indexed (indirect) addressing. Could someone help how to better / otherwise execute the code from the Z80 / 6502 but that it would work identically in 68K (as an...