From ca9049cce5f2815c7f546c2edcd1ebfd0eb8194c Mon Sep 17 00:00:00 2001
From: ripsaw8080 <ripsaw8080@users.sourceforge.net>
Date: Sun, 14 Feb 2016 04:02:09 +0000
Subject: [PATCH] Implement BIOS beep sound for ASCII character 7.

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3968
---
 src/ints/int10_char.cpp | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/ints/int10_char.cpp b/src/ints/int10_char.cpp
index a672d2ba..daf9c8ab 100644
--- a/src/ints/int10_char.cpp
+++ b/src/ints/int10_char.cpp
@@ -589,9 +589,21 @@ static void INT10_TeletypeOutputAttr(Bit8u chr,Bit8u attr,bool useattr,Bit8u pag
 	Bit8u cur_row=CURSOR_POS_ROW(page);
 	Bit8u cur_col=CURSOR_POS_COL(page);
 	switch (chr) {
-	case 7:
-	//TODO BEEP
-	break;
+	case 7: /* Beep */
+		// Prepare PIT counter 2 for ~900 Hz square wave
+		IO_Write(0x43,0xb6);
+		IO_Write(0x42,0x28);
+		IO_Write(0x42,0x05);
+		// Speaker on
+		IO_Write(0x61,IO_Read(0x61)|3);
+		// Idle for 1/3rd of a second
+		double start;
+		start=PIC_FullIndex();
+		while ((PIC_FullIndex()-start)<333.0) CALLBACK_Idle();
+		// Speaker off
+		IO_Write(0x61,IO_Read(0x61)&~3);
+		// No change in position
+		return;
 	case 8:
 		if(cur_col>0) cur_col--;
 		break;