# RetroBIOS for muOS

Copy `RetroBIOS.muxapp` to the card, open it from muOS's archive manager to
install it, then start **RetroBIOS** from **Applications**.

It checks the BIOS folder (`/run/muos/storage/bios`) against the files its
emulators read and installs the missing ones: downloaded with a network
connection, or from a pack copied to the root of the card without one.

It runs in muxterm, muOS's terminal. With PortMaster installed, gptokeyb2
turns every button into a key and muxterm is told to leave the pad alone, so
each button is sent once: D-pad to move, A or Start to choose, B or Select to
go back, X to tick a system, Y for the options. L1 and R1 do nothing in
muxterm, which keeps Page Up and Page Down for its own scrollback. Hold
Select, then press Start to quit. Without PortMaster, muxterm reads the pad
itself (Y then ticks a system) and Menu closes it.

With no button pressed on its first screen for 5 minutes, it closes by
itself: a pad the system cannot read then never leaves it stuck.

Not tried on a device yet: the icon, and whether muxterm honours SDL's
controller allow-list as SDL 2.30 does.