gigatron/rom/Contrib/lb3361/runjs

RUNJS 128K

This version of the online gigatron emulator differs from the original one by Phil Thomas in the following ways:

• fix rare opcodes such as st(IN,[d],X).
• small changes to help JavaScript JIT compilers.
• make audio and self-adjusted timing more robust.
• implement 128k RAM&IO expansion board.
• emulates a SD card connected to the expansion SPI.
• optionally uses python3's web server

The development source of this version of runjs is at https://github.com/lb3361/gigatron-rom/tree/master/Utils/runjs and will be synced here from time to time. This is the emulator available at http://gigatron128k.com.

Usage

Without a web server

Assuming you have python >= 3.10, type

$ python3 http-server.py

and point your browser to url http://127.0.0.1:8000.

With a web server

Copy the contents of the html directory into your server pages.

Note that the disk image sd.vhd.gz comes compressed. To serve such a compressed image with Apache, use the contents of apache-htaccess as a .htaccess file. Otherwise you have to uncompress this file.

How to

How to emulate a Gigatron 32k or 64k

Search for the following in file html/main.js

    let cpu = new Gigatron({
        hz: HZ,
        romAddressWidth: 16,
        ramAddressWidth: 17,
    });

and change ramAddressWidth to 15 for a Gigatron 32k and 16 for a Gigatron 64k. This disables both the emulation of the RAM&IO expansion board and the SD card.

How to use a different ROM

Change the symbolic link html/gigatron.rom. Alternate roms can be found in directory html/roms.

How to use a different SD card

The SD cards are represented by VHD files containing images of a FAT32 filesystem. Such images can be created with a variety of tools such as https://github.com/lb3361/dosfs.

The simplest way is to mount a VHD file using the "Mount VHD" button or by dragging a VHD file onto the emulator.

The symbolic link html/sd.vhd or html/sd.vhd.gz points to a disk image that is preloaded when the emulator starts. Note that the default image is compressed and require installing a special .htaccess file in an actual web server. Alternatively, uncompress the image and name it sd.vhd instead of sd.vhd.gz.

License

The original program is under Phil's license in file LICENSE. The modifications are contributed under the same license.