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7800AsmDevKit Overview

7800AsmDevKit is a collection of tools required for developing games for the 7800 in assembly code. It contains the following components:

  • Dasm - the popular 6502 assembler
  • 7800sign - to cryptographically sign 7800 A78 or ROM images
  • 7800header - to add/update/edit headers on A78 or ROM images

Download and Release Info




release info: 7800header updates - fixed bug where 7800mega1/2 were being stripped on reload. Dasm updates - if memory is exhausted for pass buffer growth, the existing sized pass buffer will be cleared and reused.


1. Unzip the 7800DevKit package and move the new directory to a convenient location, renaming the directory if you like.

2. Run the installation script for your Operating System and follow the on screen instructions:

Linux or OS X: open a terminal, "cd" to the 7800AsmDevKit directory, and type "./install_ux.sh"

Windows: open a CMD window, "cd" to the 7800AsmDevKit directory, and type "install_win.bat"

If you move or upgrade, simply re-run the script again to register the new location, and re-open any command windows.

Usage Overview

To assemble a binary ROM image from 7800 source code with dasm, open a terminal/CMD window and type:

7800asm sourcefile.asm

This will also run the 7800sign utility to cryptographically sign the resulting binary for the 7800.

You are, of course, welcome to run dasm and 7800sign manually if you wish.

The samples/simple directory contains simple.asm 7800 source code that you may examine and test with.

To create an A78 file for emulators, simply type the following, substituting your own filename for BINFILENAME:

7800header BINFILENAME

To modify an existing A78 file, simply type the following, substituting your own filename for A78FILENAME:

7800header A78FILENAME


Dasm is copyright 1988-2020 by dasm contributors, and distributed under the GPL. See the provided source code package for details.

7800sign is copyright 2005 by Bruce Tomlin.

7800header is copyright 2015-2020 by Mike Saarna, and distributed under the GPL.