read all other bits of mpu-401 status register as 1HEADv0.3.3master

this improves compatibility with windows nt 3/4's builtin soundblaster
driver

5 files changed, 8 insertions, 2 deletions

diff --git a/.gitignore b/.gitignore
index 77e7fb1..599ea2a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ out
 *.vbox-extpack
 VirtualBox.src
 VirtualBox.*
+*.creator.user
diff --git a/ExtPack.xml b/ExtPack.xml
index 46106ae..4e13cfe 100644
--- a/ExtPack.xml
+++ b/ExtPack.xml
@@ -2,7 +2,7 @@
 <VirtualBoxExtensionPack xmlns="http://www.virtualbox.org/VirtualBoxExtensionPack" version="1.0">
     <Name>VMusic</Name>
     <Description>Adds virtual devices for common music hardware: Adlib card (OPL2/OPL3), MPU-401 compatible (UART mode only), and SBAWE32 (EMU8000).</Description>
-    <Version revision="302">0.3.2</Version>
+    <Version revision="303">0.3.3</Version>
     <MainModule>VMusicMain</MainModule>
     <MainVMModule>VMusicMainVM</MainVMModule>
 </VirtualBoxExtensionPack>
diff --git a/Mpu401.cpp b/Mpu401.cpp
index 450aedd..eadd1a2 100644
--- a/Mpu401.cpp
+++ b/Mpu401.cpp
@@ -301,7 +301,10 @@ static uint8_t mpuReadStatus(PPDMDEVINS pDevIns)
          0 - Data is available for reading
          1 - No data is available for reading */
 
-    uint8_t status = 0;
+    /* All other bits are undefined, but software such as
+     * NT's sndblst.sys expects them to be read as 1. */
+
+    uint8_t status = 0xFFU & ~(RT_BIT(6) | RT_BIT(7));
 
     Log7Func(("tx buf=%zu/%zu rx buf=%zu/%zu\n",
               RTCircBufUsed(pThis->pTxBuf), RTCircBufFree(pThis->pTxBuf),
diff --git a/README.md b/README.md
index 43abd19..fed53f4 100644
--- a/README.md
+++ b/README.md
@@ -155,6 +155,8 @@ After this, just type `make` followed by `make pack` and `VMusic.vbox-extpack` s
 
 # Changelog
 
+* v0.3.3 minor change to MPU-401 to improve compatibility
+
 * v0.3.2 minor changes to fix compatibility with VirtualBox 7.0.0
 
 * v0.3.1 EMU8000 RAM is now saved in snapshots,
diff --git a/scripts/runvm.sh b/scripts/runvm.sh
index c7471ea..c7471ea 100644..100755
--- a/scripts/runvm.sh
+++ b/scripts/runvm.sh