Showcase your customasm project here!

[hlorenzi]

I think this new Discussions space would be perfect to showcase projects using customasm! I'm also really curious and it always brings me joy to see people using it and finding it useful! If you have a public project that you want to showcase, please reply here! I might compile a list later and feature it more prominently.

Also, if you've created a definition file for a widely-known CPU and you'd like to include it as a standard <std> file in customasm, you can open a pull request for its inclusion! These <std> files are always shipped with the app.

[pol-rivero]

This sounds like a great idea! Here's my project:
I'm working on a 16-bit homebrew CPU, here's a draft of the documentation. The supported instruction set is in the second page.

I'm (obviously) using customasm for assembling my custom language (this is the ruledef file), but I've recently also integrated cpp for a more robust preprocessor, as was discussed here. This allows me to use #define+#ifndef for including the same file twice without the assembler complaining.
I'm also using the preprocessor on the ruledef file for making the macro definition a bit easier, but full macro support in customasm would be a lot nicer.

And one more thing: if you're using Notepad++ to code in your custom language, I would recommend you also create your custom syntax highlighting and autocompletion. It's surprisingly easy and it makes coding much easier. Here's an example.

Here are some example programs in my custom language.

Thank you @hlorenzi for this amazing tool. I can't wait to see what you guys have done and get some ideas for my projects.

[moonheart08]

Little bit of advice, but if you want to try and unify your IO controllers together, maybe take a peek at the Parallax Propeller 2. It can handle driving an HDMI/DVI video display, keyboard inputs, and audio, albeit in software, but it has more compute power than you'd need for all those tasks (Read: You'd only need one P2 vs the two nanos). A dev board for it is much more expensive than the nanos though. Your architecture is quite neat.

[pol-rivero]

Thank you for the advice! I'm still figuring out the whole I/O thing so I'll definitely check it out.
It looks a bit overkill, though. My goal is to minimize how much I rely on microcontrollers that are much more powerful than the main CPU, and the P2 looks several orders of manitude faster than the AtMega.
But anyways, I'll have a look the P2. It looks quite promising and it may be useful for other projects.

[rj45]

I have a youtube series:

Building a CPU From Scratch

I am using Digital to build a CPU in a more graphical way that is hopefully more approachable than Verilog or VHDL. The ultimate goal is to build a CPU capable of running an OS like Xinu or Xv6. That's going to take a good long while though.

Eventually I will put the CPU up on github under a MIT license. I might find time to do that soon, we will see.

In the latest episode [016] A Proper Assembler! I cover customasm and plan to use it going forward.

I must say, thank you very much @hlorenzi for this amazing program! It saves me tons of time as I build and iterate on the custom CPUs I like to build for fun.

[rolf-electronics]

I used customasm to program my 8 bitbreadboard computer.

More info:
https://www.reddit.com/r/beneater/comments/njx7lp/customasm_using_customasm_is_cool_made_by/
https://www.reddit.com/r/beneater/comments/njf23n/programming_a_breadboard_computer_via_customasm/

Description of my build
https://github.com/rolf-electronics/The-8-bit-SAP-3

Thanks for making this assembler, awsome job and a bunch of work I assume

[parasyte]

Started working on an assembler for Atari Jaguar's RISC CPUs (a GPU and a DSP): https://github.com/blipjoy/blipjag

[physnoct]

I made a software implementation of a multibyte CPU, some sort of a Z80 on steroids!
https://physnoct.wordpress.com/2020/09/05/a-super-duper-8-bit-microprocessor-on-steroids/
https://github.com/physnoct/softmicro

I used a previous version of customasm. It was quite easy to learn and I was able to make the complete instruction set.

[ivan-pi]

I wrote a customasm definition for Little Computer 3 (LC-3): https://gist.github.com/ivan-pi/02df963d013637bab10f0c1306b9a0ea

It came together in one afternoon thanks to how expressive customasm is. Kudos for writing such a great tool!

The one thing I couldn't figure out was, how to make sure the relative-offset addressing is safe. The offsets are based on the current program counter:

PCoffset9  A nine-bit signed 2’s complement integer (bits [8:0] of an instruction), 
           used with the PC+offset addressing mode. Bits [8:0] are sign-extended to
           16 bits and then added to the incremented PC to form an address. 
           Range −256..255.

PCoffset11 An eleven-bit signed 2’s complement integer (bits [10:0] of an instruction), 
           used with the JSR opcode to compute the target address of a subroutine call. 
           Bits [10:0] are sign-extended to 16 bits and then added to the incremented PC 
           to form the target address. Range −1024..1023.

Maybe I can open a new discussion for this? Nevermind, I didn't notice the offset is with respect to the incremented program counter.

[ivan-pi]

I've also used customasm in a CHIP-8 project: https://github.com/ivan-pi/FC8/blob/Xlib/asm/chip8.asm

There are a few different conventions in use for the CHIP-8 instruction mnemonics. Mine follows Cowgod's Chip-8 Technical Reference page.

In the future I'd also like to do SWEET 16. Ideally it would be done in a way that it can be inter-mixed with your existing 6502.asm, just like Wozniak used it.