ASM80: New directives, some fixes, new login system

 My projects, Programming  Comments Off on ASM80: New directives, some fixes, new login system
Sep 162017

Hello folks, as you can noticed, there is some progress with online IDE and compiler.

Last time I have introduced new features: generic emulator and assembler toolkit.

Today I would like to introduce some features you will love, I guess…

First of all: ASM80 Manual, published with GitBook. Enjoy!


I have added three directives: .cstr, .pstr and .istr. All of them is suitable for defining a string, like DB “blahblah”, but:

.cstr When you need write a zero-ended string (C style), you can use DB "Hello",0 – or simple .cstr "Hello"
.pstr Similar as .cstr, but there is no trailing zero. .pstr is a Pascal-style string: first byte is length, then string. So .pstr "Hello" is equal to DB 5, "Hello".
.istr Strings are often defined as simple ASCII, where the last byte has bit 7 set to 1. So .istr "Hello" is the same as DB "Hell","o"+0x80

Terminal capturing and transmitting

With Generic Emulator you can now easy capture terminal out to the text file (press “capture” under the display, press again to stop capturing and save file). You can send file to terminal too, just click to the file name with RMB and select “Send to terminal”

New login system

I have decided to deprecate old login system, it was not good. From now you can log in with GitHub account, Twitter account, Google account or Facebook account. You can link more such accounts together, of course. Your workspaces is now saved in Firebase DB. Your old workspaces are preserved, but it requires old way of login, so I recommend to save them into the new system.

Bug fixed

There was a bug in a .block feature – in some circumstances with 6502 code assembler can decide to use shorter addressing mode, so .block can be moved during the evaluation passes to another address. Now assembler reflect these changes and provide true addresses for inner @labels.

Assembler toolkit

 My projects  Comments Off on Assembler toolkit
Sep 092017

Wanna convert HEX to series of DB? Or binary file to series of DB? Or wanna convert them to the JavaScript Array form? Or you have a LST file and want to convert it to ASM, so trim first 20 (or 16, or 18, or 32) characters? It’s easy with the ASM80 Tools.

Assembler for 8080, Z80, 6502 and much more…

 6502, Microprocessors, My projects, Programming, Z80  Comments Off on Assembler for 8080, Z80, 6502 and much more…
Nov 272016

Readers certainly know my ASM80 – online assembler / IDE for eight-bit processors. I made several derived versions, like single page compiler, embedded version of the translator (I used it in tutorial Strojá, or a stand-alone IDE. The good old command line assembler is here now too.

The prerequisite you have to meet is a functional Node.js environment. It is not complicated, it exists for all major platforms, and you can download it here: During installation, package manager called NPM is installed too.

NPM is used for install the packages and libraries. To install ASM80 itself just run a command prompt and type:

-g causes the asm80 will not be installed as a library, but as a system tool. Then toy can invoke it as a standard command line utility:

launches translation for file test.a80 and the result will be two files: test.hex with output and test.lst with the translation protocol. Extension .a80 tells the compiler to use the processor’s instruction set for Intel 8080 CPU.

Behaviour can be influenced by parameters. You can set the output file name, you can suppress the generation .lst, or explicitly determine the processor type and format of the output file (besides HEX and S record it can output .COM files for CP/M, .PRG for C64 emulators, or SNA and TAP for ZX Spectrum).

Options are:

  • -o, --output <file> Output file name
  • -t, --type <type> Output type [default: hex]. Available types are: hex, srec, com (for CP/M), sna, tap (for ZX Spectrum), prg (for C64)
  • -n, --nolist Suppress listing (.lst file)
  • -m, --machine <type> Processor type, one of the following: Z80, I8080, C6502, C65816, CDP1802, M6800, M6809
  • -h, --help See HELP

Machine type can be omitted. Right CPU is determined by file name extension (-m option overrides this decision).

  • Intel 8080: .A80
  • Zilog Z80: .Z80
  • Motorola 6800: .A68
  • Motorola 6809: .A09
  • MOS 6502: .A65
  • WDT 65816: .816
  • CDP 1802: .A18

These parameters are described on page NPM package ASM80.

Overview of the syntax and directives can be found on GitHub Pages.

I still have a few suggestions for improvements, I would like to know your opinion …

  • Create a library system, as it has the classic assemblers, which separates translation and linking. So users will have the opportunity to make a library of subroutines, which would include only those parts of the code that are necessary for proper function. You can easily make something like the “standard C library” for your system …
  • Having the opportunity to directly link public code, for example on GitHub.
  • … More processors? Systems?

Thanks for the tips and suggestions. You can send them straight to the GitHub Issues.

Nov 152014

A long time ago I started to play with 8bit CPUs and old computers… again.

There is a lot of development tools for these computers, a tons of assemblers and utilities for any OS, from CP/M to Mac OS, DOS, Linux and Windows including. So there is no space for a new one. But internet is a magic “big space for everything”. 🙂

When I bought Phil’s V6Z80P, I used PASMO assembler. It is a great state-of-the-art assembler, really perfect. But over time I had a lot of assemblers, compilers and IDEs for different CPUs somewhere on my disk. And one day my disk crashed. So I wished to have “an online PASMO”.

At first I made online editor with server-side PASMO. You wrote a code in your browser, pressed COMPILE, code went to the server, PASMO did its magic and send back my HEX (or BIN or whatever). Great thing! Later I’ve added FLASH-based Spectrum emulator, so I could write programs for ZXS, compile it and try it directly in emulator. But I never published this tool.

One year ago I’ve decided to reinvent my wheel again, and this time without server back support. I choose text editor in JavaScript and start development of my very own assembler engine. My goal was to create a modular assembler for different 8bit CPUs, from 8080 to 6809, with simillar syntax. I’ve integrated it with the editor into one “IDE”. Later I added CPU emulating engines, so you could debug your compiled code. Then I added whole computer emulations…

And all of this is free, online, partially open source.

The main part is This is a web-based IDE with following features:

  • Code editor
  • Simulated workspace for your files (it’s stored technically in your browser, so you haven’t to got any “server account”)
  • Compiling engines for 8080/8085, Z80, 6502, 6800 and 6809 CPU
  • Embedded emulators for all these CPUs
  • Emulators for some computers:
  • Nearly the same syntax and directives for all CPUs
  • Macros
  • Preprocessor

Here is an assembler description and here is source code for the engine.

During my work on ASM80 I developed some minor things in JavaScript. All of these are open source too: 6850js (6850 emulator), 6809 emulator or enhanced 8080js emulator, which can pass through the Examiner test (so every bit works, every T cycle is valid…)

Then I’ve derived small one-page assemblers for all supported CPUs. You can save it in your Favorites or at your local disk and use for simple compiling.

And the newest part of ASM80 family is an IDE80. It’s technically ASM80, with IDE, assembler, debugger and emulatore, repacked and compiled as a desktop application. It’s in beta version, just for Windows at this time, but Linux and Mac OS X versions should came very soon. You can watch a video showing first steps with this IDE.

At this time I’m working on further improvements:

  • Structures in assembler
  • C64 or Atari emulator in JavaScript
  • KIM-1 emulator
  • modules for generating not just HEX or S19, but TAP, SNA, PRG and other popular formats for 8bit computers.

Update 11/16/2014: Beta version of KIM-1 emulator is ready and deployed…


Oct 072014

I made a little spin-off of ASM80 IDE. You can use the compiler locally, offline, in a simple way.

Visit asm8080, asm6502, asm6809 or asmZ80. You can save these files to your PC (Ctrl S, or right click to the link and Save as…)

Usage is really simple: Just open the HTML file in your browser. Copy and paste the source code into a Source window and press Compile.

And yes, it provides all features of the “full” ASM80.

Mar 242014

I’ve updated my online assembler IDE recently (more info here). It can assemble / debug code for MCU Motorola 6809. The assembler is in alpha version, not yet fully compatible with old 6809 assemblers (pseudoinstructions like FCB, FCC, BSZ, RMB, ZMB are missing, but I’m working on them). The all you need is to create a file with “.a09” extension and compile it. Compiler outputs to “HEX” files (not S records yet, but it’ll be soon). Assembled code can be tested in embedded 6809 emulator, based on my code. You can use an online SBC09 emulator, which is capable to emulate Grant Searle’s 6 chip simple 6809 computer. Stay tuned for further information…