SIDE Loader and SpartaDOS X for the AVG Cart

After developing a new main BIOS and PBI BIOS for Ultimate 1MB and Incognito, I decided to write a completely new XEX loader. Presented here is the stand-alone (not requiring U1MB) ROM version of the resulting loader for the SIDE/SIDE2 cartridge in a format which will run on the popular AVG Cart. Several features are new to the revised loader; others simply build on the functionality of the original. They include:

  • Fast and powerful recursive search facility capable of scanning thousands of files and folders on FAT16 and FAT32 volumes
  • Automatic recall of the last accessed folder on the last accessed FAT partition
  • High-speed XEX loading
  • Handling of up to fourteen multiple FAT partitions
  • APT partition mounting
  • Easy mounting of multi-disk volumes via MAP files
  • Loading of 8KB ROMs and BASIC programs
  • FAT loader capable of loading files as low as $0A80
  • Optional FAT file system handler allowing read-only access to the host volume via the CIO
  • Full path support in CIO FAT file system and in MAP files
  • Handling of large (more than 250 files) folders
  • Reverse lookup of a mounted ATR or APT partition


You can download the latest version of the loader for SIDE and SIDE2 via the link below. The archive contains the stand-alone loader, SDX ROMs, and complete ROMs (SDX and loader).

SIDE Loader 4.2 and SDX 4.49e for the AVG Cart

Loader Quick Reference


See the XEX Loader section in the U1MB/Incognito/SIDE firmware manual for details of how to use the new loader.

Licensing and Donations

While the firmware is free at the point of delivery for personal use, if it is to be supplied as an integral component of a commercially sold device, the firmware is subject to a licensing fee which should be arranged with the author in advance. Developers interested in customised versions of the firmware tailored to their particular hardware should contact the author.

In light of the fact that firmware licensing revenue is modest and that updates are offered for free to the end user, donations are welcomed and appreciated. Indeed, it has been my mission to facilitate easy and safe firmware updates, and regular in-the-field upgrades are encouraged to ensure that devices remain up to date and bug fixes are delivered in a timely manner.

Thank you!

Tutorial Videos