ChibiAkumas ASM Programming Forum

The book has a few examples (3 for each cpu) which were tested on the Devtools in my tutorials - these are basically the ones from the 'Simple series' (You can download them from the book page for free - link below) , but the majority of the book is a general overview of assembly programming and the ...

I never mentioned the GX4000 - but it's clearly famous enough for you to have heard of it.

Oh, and I knew precisely one person with a SMS in the UK in my lifetime, there were four with CPC computers in my street when I was growing up - popularity varies by country you know!

I cover checksums here ...

There isn't one, I never read back from VRAM.
Getting a char from the screen like that may work on the SMS, but won't on a bitmap screen like the CPC, so If I need to know what's onscreen I store it in memory somewhere else so I have a solution that is portable across systems.

If you want to do it ...

The Vblank interrupt happens 50 times a second.
I think that's your best way to do timing. Put a counter routine in the interrupt handler.

I'm afraid I don't have a tutorial on SMS dedicated to interrupts, but they were mentioned in my lightgun tutorial

https://www.chibiakumas.com/z80/platform6 ...

I don't think I've done that, but I'm sure you can figure it out yourself!

Take a look at VDP regsiters:
&08 Background X Scroll T T T T T P P P T = Tile offset (0-31), P=Pixel offset
&09 Background Y Scroll T T T T T P P P T = Tile offset (0-27), P=Pixel offset

Palette settings are covered here:
https://www.chibiakumas.com/z80/platform2.php#LessonP16

It's just 2 bits per color channel though, so it's not too hard to figure out. The "--BBGGRR" in the file you sent should mark the correct bits that make up each color channel.

Theres a list of the platform ...

The SMS/GG has two 16 color palettes.
The background can use palette 0 or palette 1, but sprites always use Palette 1
You've only defined palette 0 - so the sprites are black

Double the entries in PaletteData (copy the existing 16 entries a second time for starters)
Change "ld b,16 ;Byte count (16 ...

Double byte Write.

I believe i based the table on the information in this document:
https://patpend.net/technical/snes/snes.txt

Yes, that's what I'd recommend you use.

Your 'V' text is in the same part as the program as your code.

The Z80 is trying to run it, and it's causing a crash.

You need to put it somewhere the CPU will never run - for example after the HALT.

Oh, the tabs were a bit messed up in the code comment, but that may just be a copy-paste issue ...