Assembler for a modified version of the Chip-8 instruction set
To compile, run gcc -o asm.exe asm.c.
Then, once you have written your assembly program, run ./asm.exe [programname.asm]. The assembled file will be saved as "program.hex".
The base instruction set can be found here. However, there are a few additions to this program.
The instruction ld I, vx was added, which sets the value of the I register equal to the value in vx.
Comments are defined with ';', as follows:
cls ;Clear Screen
ret ;Return from subroutine
Anchor points are predefined places where a program can jump to. They can be created as follows:
.myAnchorPoint
;Implement routine here
Later, Anchor points can be called like this:
jp myAnchorPoint
;PC is set to the place where myAnchorPoint was defined
It is important to remember that all words are converted to lowercase during the assembly. Therefore, 'myanchorpoint' and 'MYANCHORPOINT' are equivalent.
The binary values of a few instructions were also altered to make room for more instructions in the future.
Unfortunatley, since this is a modified set, preexisting emulators will not work out of the box. You may be able to modify one or write your own to run your program. I am also working on an emulator, but I do not feel that it is complete enough to publish. However, it is in a functional state, so I was able to test the assembler to make sure it was working. I even got Pong running, as shown below. 