diff --git a/doc/comboot.txt b/doc/comboot.txt
index f5fefda..1450021 100644
--- a/doc/comboot.txt
+++ b/doc/comboot.txt
@@ -955,3 +955,38 @@ AX=0024h [3.80] Cleanup, shuffle and boot, raw version
 	with read/write data segments, matching the respective code
 	segment.  For mode 0, B=0 and the limits will be 64K, for mode
 	1, B=1 and the limits will be 4 GB.
+
+
+AX=0025h [3.84]	Set current working directory
+	Input:	AX	00025h
+		ES:BX	null-terminated directory name string
+	Output:	None
+
+	Sets the current working directory.  For SYSLINUX, ISOLINUX,
+	and PXELINUX, this will be an absolute path.
+
+
+AX=0026h [3.84]	Read file system metadata [ISOLINUX]
+	Input:	AX	00026h
+	Output:	None
+
+	Reads filesystem data (e.g. after a CDROM change).
+
+
+AX=0027h [3.84] Run command
+	Input:	AX	0027h
+		ES:BX	null-terminated command string
+		SI	comboot callback function (called via far call)
+		EDI	kernel load address
+		EDX	if != 0: initrd load address (that is: memory end)
+	Output:	Does not return if the kernel loads correctly.
+
+	Executes the command line as if it had been entered by the user.
+	Note that this function does return (with CF = 0) if there are
+	problems or the user aborted the load. Else it terminates the
+	COMBOOT program and starts the kernel.
+
+AX=0028h [3.84] Get memory size
+	Input:	AX	0028h
+	Output:	EAX	high memory size (in bytes)
+
