5 ms·

Yes, it's all written in z80 assembly, although the GameBoy CPU really uses a mix of i8080 and z80 instructions, the mnemonics are all z80. I've also written my

Yes, it's all written in z80 assembly, although the GameBoy CPU really uses a mix of i8080 and z80 instructions, the mnemonics are all z80. I've also written my own assembler just recently, to have more control over the output and more easily generate debugging information: https://github.com/BonsaiDen/gbasm https://github.com/BonsaiDen/gbasm

glhaynes 12y ago
although the GameBoy CPU really uses a mix of i8080 and z80 instructions, the mnemonics are all z80. I'd love to hear more about this if anybody knows and feels like telling about it...
- userbinator 12y ago
  It's a Z80-like core with some modifications; not all the Z80 instructions and registers are present and some instructions are completely different. Most instructions are the same as the 8080, but all 3 CPUs are not completely binary-compatible. It's neither truly an 8080 with added instructions, nor a Z80 with omitted ones. For comparison: http://pastraiser.com/cpu/gameboy/gameboy_opcodes.html http://pastraiser.com/cpu/gameboy/gameboy_opcodes.html http://pastraiser.com/cpu/i8080/i8080_opcodes.html http://pastraiser.com/cpu/i8080/i8080_opcodes.html
harwoodr 12y ago
"my own assembler" - now you're just showing off. :)
- BonsaiDen 12y ago
  Nah' I would only be showing off if I were to put it onto a real cartrdige and GameBoy, wouldn't I? ;) - https://dl.dropboxusercontent.com/u/2332843/tuff.cartridge.jpg https://dl.dropboxusercontent.com/u/2332843/tuff.cartridge.j... - https://www.youtube.com/watch?v=yXNEeld8Lq8 https://www.youtube.com/watch?v=yXNEeld8Lq8
  - stevelosh 12y ago
    If folks want to try it on a real Gameboy without all the wires, the Drag'n'Derp works pretty well. It's a Gameboy cart with a USB port for easy writing: http://derpcart.com/ http://derpcart.com/
    - BonsaiDen 12y ago
      I was looking at these option initially too, but ended up going for the challenge since, both I read some not-so-good reviews and shipping the thing to germany would probably ended up being at least as expensive as buying the soldering equipment :) Building one of those custom GamePaks takes about ~4 hours once you have all the materials prepared (you really need very, very thin wires!) and putting it together for the first time is one of those finger crossing moments which you'll remember for a really long time :)
      - DanBC 12y ago
        I took a cart, removed the game IC, and soldered in a ZIF socket for eproms. And I'm a klutz so it's easy enough. http://www.devrs.com/gb/files/faq.html http://www.devrs.com/gb/files/faq.html
        voltagex_ 12y ago
        Am I right in thinking that GameBoy carts are now a precious resource? We'll run out one day?
        JonnieCache 12y ago
        Pretty sure you could make your own with a 3d printer and one of those kitchen PCB-etching setups you see people using. There's no magic in there AFAIK.
    - ant512 12y ago
      The Everdrive GB takes micro SD cards, so it has more space: http://krikzz.com/index.php?route=product/product&product_id=60 http://krikzz.com/index.php?route=product/product&product_id...
- phaer 12y ago
  It sounds very advanced but an assembler for a rather simple architecture like z80 is much easier to write like most (other) compilers for example.
- ams6110 12y ago
  Used to be a standard 2nd or 3rd year assignment in a comp. sci. curriculum. Not sure if it is anymore.
tete 12y ago
Nice! Also nice that these days Assemblers get written in JavaScript. ;)
- pjmlp 12y ago
  Well, they used to be written in Basic as well, so given that JavaScript has apparently taken Basic's role....
jldugger 12y ago
When I was tinkering with gbdev 15 years ago, we had lcc targetting z80. It seems far less painful to write in C than asm.
- vegedor 12y ago
  C is just an advanced macro-assembler anyway. Would seem painful enough as soon as speed or size became limited. C then was not as optimized as today. Old games used to be written in assembler, now the eeproms are bigger, the compilers are faster and portable.

glhaynes 12y ago

although the GameBoy CPU really uses a mix of i8080 and z80 instructions, the mnemonics are all z80. I'd love to hear more about this if anybody knows and feels like telling about it...

userbinator 12y ago
It's a Z80-like core with some modifications; not all the Z80 instructions and registers are present and some instructions are completely different. Most instructions are the same as the 8080, but all 3 CPUs are not completely binary-compatible. It's neither truly an 8080 with added instructions, nor a Z80 with omitted ones. For comparison: http://pastraiser.com/cpu/gameboy/gameboy_opcodes.html http://pastraiser.com/cpu/gameboy/gameboy_opcodes.html http://pastraiser.com/cpu/i8080/i8080_opcodes.html http://pastraiser.com/cpu/i8080/i8080_opcodes.html

harwoodr 12y ago

"my own assembler" - now you're just showing off. :)

BonsaiDen 12y ago
Nah' I would only be showing off if I were to put it onto a real cartrdige and GameBoy, wouldn't I? ;) - https://dl.dropboxusercontent.com/u/2332843/tuff.cartridge.jpg https://dl.dropboxusercontent.com/u/2332843/tuff.cartridge.j... - https://www.youtube.com/watch?v=yXNEeld8Lq8 https://www.youtube.com/watch?v=yXNEeld8Lq8
- stevelosh 12y ago
  If folks want to try it on a real Gameboy without all the wires, the Drag'n'Derp works pretty well. It's a Gameboy cart with a USB port for easy writing: http://derpcart.com/ http://derpcart.com/
  - BonsaiDen 12y ago
    I was looking at these option initially too, but ended up going for the challenge since, both I read some not-so-good reviews and shipping the thing to germany would probably ended up being at least as expensive as buying the soldering equipment :) Building one of those custom GamePaks takes about ~4 hours once you have all the materials prepared (you really need very, very thin wires!) and putting it together for the first time is one of those finger crossing moments which you'll remember for a really long time :)
    - DanBC 12y ago
      I took a cart, removed the game IC, and soldered in a ZIF socket for eproms. And I'm a klutz so it's easy enough. http://www.devrs.com/gb/files/faq.html http://www.devrs.com/gb/files/faq.html
      - voltagex_ 12y ago
        Am I right in thinking that GameBoy carts are now a precious resource? We'll run out one day?
        JonnieCache 12y ago
        Pretty sure you could make your own with a 3d printer and one of those kitchen PCB-etching setups you see people using. There's no magic in there AFAIK.
  - ant512 12y ago
    The Everdrive GB takes micro SD cards, so it has more space: http://krikzz.com/index.php?route=product/product&product_id=60 http://krikzz.com/index.php?route=product/product&product_id...
phaer 12y ago
It sounds very advanced but an assembler for a rather simple architecture like z80 is much easier to write like most (other) compilers for example.
ams6110 12y ago
Used to be a standard 2nd or 3rd year assignment in a comp. sci. curriculum. Not sure if it is anymore.

tete 12y ago

Nice! Also nice that these days Assemblers get written in JavaScript. ;)

pjmlp 12y ago
Well, they used to be written in Basic as well, so given that JavaScript has apparently taken Basic's role....

jldugger 12y ago

When I was tinkering with gbdev 15 years ago, we had lcc targetting z80. It seems far less painful to write in C than asm.

vegedor 12y ago
C is just an advanced macro-assembler anyway. Would seem painful enough as soon as speed or size became limited. C then was not as optimized as today. Old games used to be written in assembler, now the eeproms are bigger, the compilers are faster and portable.