What does BBS mean?

This is a low-level interface provided by motherboard firmware (i.e. not from installation media) that can be accessed before any OS is loaded. This is similar to BIOS set up but its only function is to allow a user to select which device they would like to boot from. This is useful for doing things like booting from USB flash drives or selecting from among multiple bootable hard drives.

To bring up this menu the user must press a magic key before anything loads. It can be tricky to know just which key to press since the boot process (ideally) goes by very quickly. Usually when I find out what the magic key is I write it on the computer itself. I’m going to keep a list of such things here in case any common themes can suggest intelligent guesses for unknown machines.


  • HP Pavilion Slimline (kiwi)

  • "System Setup" - Minix tiny computer with AMI BIOS

  • "BBS" - Asus eee 1001P-PU17

  • "BBS" - Asus laptop - F5100A


  • Dell PowerEdge 510 - BIOS

  • Dell P28F Laptop - BIOS

  • Asus eee 1001P-PU17 - BIOS

  • Asus laptop - F5100A - BIOS


  • Asus mini-itx (raven)

  • Asus workstation (ws14-ab)

  • Windows XP’s "startup options menu" where you can select "safe" mode.


  • "System Services" Dell PowerEdge 510


  • Gigabyte server motherboard (fs11-ab)

  • "BBS" - Dell PowerEdge 510

  • "BBS" - SuperMicro

  • "BBS" - Minix tiny computer with AMI BIOS

  • "BBS" - Zt BIOS on ZT machine.


  • Dell Precision Tower 5810

  • Dell Optiplex 7050

  • "PXE" - Dell PowerEdge 510

  • Gigabyte GA-970A-DS3P AM3+ socket

  • Dell P28F Laptop - BBS


  • "RAID" - Dell PowerEdge 510


  • Show POST - SuperMicro


  • Setup - SuperMicro

  • Setup - AMI, Asus (raven15),

  • Setup - AMI, Qotom MiniPC (raven21),

  • Setup - Zt BIOS on ZT machine.

  • Setup - Gigabyte GA-970A-DS3P AM3+ socket


Drop Alt Keyboard

  • [F]-Esc - Backtick `

  • [F][S]-Esc - Tilde ~

  • [F]-w - LED brightness increase

  • [F]-a - LED pattern select previous

  • [F]-s - LED brightness decrease

  • [F]-d - LED pattern select next

  • [F]-q - LED scrolling pattern speed decrease

  • [F]-e - LED scrolling pattern speed increase

  • [F]-Tab - LED breathe effect toggle

  • [F]-CapsLock - LED toggle scrolling pattern direction

  • [F]-x - LED toggle OFF/ON

  • [F]-z - LED toggle mode (keycaps+base, keycaps, base)

  • [F]-1 (and 2-9) - F1 (and F2-F9)

  • [F]-0 - F10

  • [F]-dash - F11

  • [F]-= - F12

  • [F]-n - Toggles 6KRO vs. NKRO, which is Key Roll Over, 6KRO means only 6 key events can be left in a pressed state at a time. NKRO is an arbitrarily number.

  • [F]-p - Print Screen (xev: keycode 107, keysym 0xff61, Print)

  • [F]-[ - Scroll Lock (xev: keycode 78 (keysym 0xff14, Scroll_Lock)

  • [F]-] - Pause (xev: keycode 127 (keysym 0xff13, Pause)

  • [F]-RightArrow - End

  • [F]-LeftArrow - Home

  • [F]-UpArrow - Page Up

  • [F]-DownArrow - Page Down (Which does make one wonder why there are physical PgUp and PgDn keys.)

  • [F]-PgUp - Volume Up

  • [F]-PgDn - Volume Down

  • [F]-Del - Volume Mute (xev: keycode 121, keysym 0x1008ff12, XF86AudioMute)

To attempt to customize firmware:

Note the USB-C port not used to connect to the host can be used as a USB hub and is rated for 2W-4W depending on host supply.

There is a hole on the base under about the "?" key which is for a paperclip reset.

EFI Shell

Because UEFI is weird and does strange things, your computer may boot into some strange kind of shell that says something like this.

EFI Shell version 2.31 [4.651] - Current running mode 1.1.2

Followed by a list of your block devices.

Device mapping table

They’ll be specified as fs0, fs1, fs2 and blk0, blk1, blk2.

I really have no idea what’s going on here and why this happen, but a cure that has worked for me if you get to this system’s shell prompt is to just type exit and it will proceed to boot like it should have done.

Mac Pre Boot

All of this is rumor. None of it was tested.

  • "Shift" - Safe mode. Recommended for things like fsck.

  • Option - Also like BBS. Perhaps for dual boot. But it claims to also be able to boot external media so I don’t know what the difference is between it and "C". Note that this can take up to a minute, usually around 30s but it was quite variable.

  • "C" - Pressed immediately after the chime allows booting from other media, basically the BBS.

  • "D" - Pressed immediately after the chime will run hardware diagnostics.

  • Command-"V" - Verbose. To get this mode all the time do sudo nvram boot-args="-v&" To disable that do this sudo nvram boot-args=

  • Command-"S" - Single user mode.

  • Eject or "F12" - Ejects a CD.

  • Command-Option-"P"-"R" - Yes, all of that. Resets NVRAM which contains speaker volume, screen resolution, start up disk selection, kernel panic log, maybe more.

  • "T" - Turns the booted Mac into a firewire external drive. Before booting it, plug it into another running Mac with a firewire cable. Hold T when booting. Again it takes a while. Eventually on the booting system a large, jumpy firewire symbol appears and on the host computer (already running fine) a new drive appears.

  • Option-"N" - Use a NetBoot default boot image. Like PXE I guess.

  • Command-"R" - OS X System recovery. Available on Macs that shipped with 10.7 (Lion) or higher. This appears to load a boot image from Apple servers for diagnostics etc.

  • "N" - PXE.

Rescue Linux On Macs

Booting SysRescCD on a Mac. I had to add this to the "linux" line in Grub.

video=vga16fb:off vga16fb.modeset=0 nouveau.noaccel=1 nouveau.modeset=0 nvidia.modeset=0

I do not know which of these additions were necessary to avoid the garbled display, but I’m noting them in case they are useful.


  • Ctrl-I seems common. Dell for example.

BIOS Checkpoint And Beep Codes

These are codes that show up in the lower right corner of AMI BIOS POST operations. They are actually incomplete because some codes are generated before video is ready to show them (there are PCI cards that can capture/display them). For problems with codes don’t forget to consider changing the CR2032 motherboard battery. Also don’t forget to update/flash the BIOS.

Here is a very good reference for AMI codes. This is also a good place to look for beep code deciphering.