diff --git a/papers/doc/7-systems/pcspkr.md b/papers/doc/7-systems/pcspkr.md
index 6c2e1a94c..50940a5a7 100644
--- a/papers/doc/7-systems/pcspkr.md
+++ b/papers/doc/7-systems/pcspkr.md
@@ -2,6 +2,30 @@
 
 40 years of one square beep - and still going! Single channel, no volume control...
 
+# real output
+
+so far this is the only system in Furnace which has a real hardware output option.
+to enable it, select file > configure system... > PC Speaker > Use system beeper.
+
+be noted that this will only work on Linux as Windows does not provide any user-space APIs to address the PC speaker directly!
+
+you may configure the output method by going in Settings > Emulation > PC Speaker strategy:
+
+- `evdev SND_TONE`: uses input events to control the beeper.
+  - requires write permission to `/dev/input/by-path/platform-pcspkr-event-spkr`.
+  - is not 100% frequency-accurate as `SND_TONE` demands frequencies, but Furnace uses raw timer periods...
+- `KIOCSOUND on /dev/tty1`: sends the `KIOCSOUND` ioctl to control the beeper.
+  - may require running Furnace as root.
+- `/dev/port`: writes to `/dev/port` to control the beeper.
+  - requires read/write permission to `/dev/port`.
+- `KIOCSOUND on standard output`: sends the `KIOCSOUND` ioctl to control the beeper.
+  - requires running Furnace on a TTY.
+- `outb()`: uses the low-level kernel port API to control the beeper.
+  - requires running Furnace as root, or granting it `CAP_SYS_RAWIO` to the Furnace executable: `sudo setcap cap_sys_rawio=ep ./furnace`.
+
+real hardware output only works on BIOS/UEFI (non-Mac) x86-based machines! attempting to do this under any other device **will not work**, or may even brick the device (if using `/dev/port` or `outb()`)!
+oh, and of course you also need the beeper to be present in your machine. some laptops connect the beeper output to the built-in speakers (or the audio output jack), and some other don't do this at all.
+
 # effects
 
 ha! effects...