Skip to content
This repository has been archived by the owner on May 23, 2024. It is now read-only.

Space vs Speed Exporting Optimizations

Jump to bottom
Matt Greer edited this page Apr 16, 2023 · 16 revisions

In AMMiSTer's settings, you have the option to choose "speed" or "space" for export optimization. What does it mean?

  • "space": when placing games onto the MiSTer, will only place exactly what is needed, using as little space as possible
  • "speed": places all cores and ROMs onto the MiSTer, then after that exports are very fast as only MRAs need to be copied

An Arcade game's files: MRA, Core (RBF) and ROM

An arcade game on the MiSTer is made up of three files (usually, some old games don't have a ROM):

  • The Core: Has an .rbf extension. This is the actual FPGA code that is simulating the arcade machine
  • The ROM: Has a .zip extension. This is a MAME ROM of the game's data.
  • The MRA: Has an .mra extension. This is a small configuration file that tells the MiSTer how to launch the game

There are two key things to note here:

  • Cores and ROMs tend to be big, while MRA files are small (just a few kilobytes)
  • The MiSTer's menu for picking an arcade game is entirely determined by MRA files

Having extra cores and ROMs on the MiSTer is not a problem. The menu will only show games that have an MRA.

"speed" Exports

When doing a speed export, all cores and all ROMs are copied onto the MiSTer. If there aren't many arcade games already on the MiSTer, this can take a good 10-15 minutes. But once all the cores and ROMS are copied over, they will never need to be copied again. When you change around your plan by adding/moving games, then doing an export, it will only have to copy over MRA files, as all the cores and ROMs are already there.

If an update adds/updates a ROM or core, speed exports will still copy those new files. But since this is usually only a game or two, it will still be fast.

"speed" Export Advantages

  • If you change around your games often, the speed increase is very nice. Instead of an export taking say 5 minutes, it only takes about 30 seconds.
  • If you use update_all, speed exports will not conflict as much. Both speed exports and update_all, will put all cores and ROMs on the SD card. After doing an update_all, restoring your arcade game plan by doing an AMMiSTer export won't take long at all.

"speed" Export Disadvantages

  • All of the cores and ROMS take up about two gigabytes of space.

"space" Exports

When doing a space export, only the cores, ROMS and MRAs that are needed to play the games you want will be copied over. Any files on the MiSTer that are no longer needed are deleted. This can save a lot of space on your SD card. If you don't change your games around often, and/or need to save space, this is the export setting for you.

"space" Export Advantages

  • Uses a lot less storage

"space" Export Disadvantages

  • They can really clash with update_all. After doing an update_all then performing a space export with AMMiSTer, it will often delete a lot of the files that update_all downloaded.

Which one should I use?

If you're not sure, go with space. If you rearrange and change your games often, speed is probably the better way to go. If you also use update_all, speed is recommended.

Clone this wiki locally