a2asm is a 6502 assembler written in Go and licensed under the MIT License.
As mentioned in Juiced.GS, it supports a "subset of the classic Merlin assembler syntax... sufficient to assemble all of the examples from Roger Wagner's Assembly Lines book."
Copyright 2020–2022, Taeber Rapczak [email protected].
$ go build -o a2asm cmd/a2asm/main.go
$ ./a2asm --help
Usage: a2asm [-headless] <ASSEMBLY_FILE>
Converts MERLIN-type assembly into 6502 binary. A 4-byte, DOS 3.3 header
comprising the origin and length is prefixed unless -headless is used.
$ ./a2asm 6502progs/bell.s >BELL.A2
After editing your program, you can use AppleCommander and LinApple to test it out on an emulated Apple //e:
$ edit 6502progs/hello.s
$ java -jar ac.jar -e disk.dsk HELLO
10 PRINT CHR$(4);"BRUN TEST"
$ java -jar ac.jar -d disk.dsk TEST
$ ./a2asm 6502progs/hello.s | java -jar ac.jar -dos disk.dsk TEST B
$ linapple --autoboot --conf $PWD/linapple.conf --d1 $PWD/disk.dsk
To run the unit tests, you can simply execute:
$ go test
To compare against the Assembly Lines programs, you'll need to extract them from the DSK images to the current folder then run:
$ ./compareall.bash
I wanted to learn 6502 assembly on a recently acquired Apple //e. I bought Assembly Lines by Roger Wagner (edited by Chris Torrence) and was introduced to the original, Merlin assembler. It was great to learn with.
When I decided to try and write my own programs, I found it easier to iterate
using VIM and LinApple on my Ubuntu laptop. I found CC65 and their CA65
assembler with its modern ideas on programming the 6502. I was soon lost in
their documentation and eventually ended up switching to using C as it seemed
to be the easier path. After porting about 50% of the line-editor ed to the
Apple //e, however, I found out that the C code that had worked in my emulator,
didn't work on the real hardware!
Somewhere along the way I forgot that I was just trying to learn 6502 assembly and maybe using a "modern" assembler wasn't the appropriate tool for the job.
So, I wrote this assembler. I wrote tests to ensure every program of Roger Wagner assembles correctly. I have not added any more features, so while it uses Merlin-style syntax, it is not 100% Merlin compatible.