diff --git a/Doc/ChangeLog.txt b/Doc/ChangeLog.txt
index b5dc12ec..2b72545a 100644
--- a/Doc/ChangeLog.txt
+++ b/Doc/ChangeLog.txt
@@ -1,7 +1,8 @@
 Version 3.1.1
 -------------
 - WBW: Version bumped due to pervasive changes
-- WBW: Preliminary support for hard disk partition support (backward compatible)
+- WBW: Preliminary hard disk partition support (backward compatible)
+- WBW: Change Propeller VGA signal timings to 60Hz refresh
 
 Version 3.1
 -----------
diff --git a/Doc/RomWBW Applications.pdf b/Doc/RomWBW Applications.pdf
index 88b84919..dcf863fc 100644
Binary files a/Doc/RomWBW Applications.pdf and b/Doc/RomWBW Applications.pdf differ
diff --git a/Doc/RomWBW Architecture.pdf b/Doc/RomWBW Architecture.pdf
index 84168f95..8a116e0a 100644
Binary files a/Doc/RomWBW Architecture.pdf and b/Doc/RomWBW Architecture.pdf differ
diff --git a/Doc/RomWBW Disk Catalog.pdf b/Doc/RomWBW Disk Catalog.pdf
index 34fa97e8..eb0583ed 100644
Binary files a/Doc/RomWBW Disk Catalog.pdf and b/Doc/RomWBW Disk Catalog.pdf differ
diff --git a/Doc/RomWBW Getting Started.pdf b/Doc/RomWBW Getting Started.pdf
index d147a2a1..65d14983 100644
Binary files a/Doc/RomWBW Getting Started.pdf and b/Doc/RomWBW Getting Started.pdf differ
diff --git a/Makefile b/Makefile
index 8253467c..741e5ef7 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,6 @@
 all:
 	$(MAKE) --directory Tools/unix
 	$(MAKE) --directory Source
-	$(MAKE) --directory Source/Images
 
 clean:
 	$(MAKE) --directory Tools/unix clean
@@ -15,5 +14,5 @@ clobber:
 	rm -f typescript
 
 diff:
-	$(MAKE) --directory diff
+	$(MAKE) --directory Source diff
 
diff --git a/ReadMe.md b/ReadMe.md
index bbd5b46e..34710692 100644
--- a/ReadMe.md
+++ b/ReadMe.md
@@ -3,7 +3,7 @@
 ## Z80/Z180 System Software
 
 Version 3.1 Pre-release  
-Thursday 23 April 2020
+Friday 8 May 2020
 
 Wayne Warthen <wwarthen@gmail.com>
 
@@ -1137,8 +1137,8 @@ applications are no longer provided.
     driver.
   - Ed Brindley contributed some of the code that supports the RC2014
     platform.
-  - Phil Summers contributed Forth and BASIC in ROM as well as a long
-    list of general code enhancements.
+  - Phil Summers contributed Forth and BASIC in ROM, the AY-3-8910 sound
+    driver as well as a long list of general code enhancements.
   - Phillip Stevens contributed support for FreeRTOS.
   - Curt Mayer contributed the Linux / MacOS build process.
   - UNA BIOS and FDISK80 are the products of John Coffman.
diff --git a/ReadMe.txt b/ReadMe.txt
index 27ad0aa6..601e8101 100644
--- a/ReadMe.txt
+++ b/ReadMe.txt
@@ -3,7 +3,7 @@ RomWBW
 Z80/Z180 System Software
 
 Version 3.1 Pre-release
-Thursday 23 April 2020
+Friday 8 May 2020
 
 Wayne Warthen wwarthen@gmail.com
 
@@ -1169,8 +1169,8 @@ applications are no longer provided.
     driver.
 -   Ed Brindley contributed some of the code that supports the RC2014
     platform.
--   Phil Summers contributed Forth and BASIC in ROM as well as a long
-    list of general code enhancements.
+-   Phil Summers contributed Forth and BASIC in ROM, the AY-3-8910 sound
+    driver as well as a long list of general code enhancements.
 -   Phillip Stevens contributed support for FreeRTOS.
 -   Curt Mayer contributed the Linux / MacOS build process.
 -   UNA BIOS and FDISK80 are the products of John Coffman.
diff --git a/Source/Doc/Architecture.md b/Source/Doc/Architecture.md
index 330d7887..ffc3120e 100644
--- a/Source/Doc/Architecture.md
+++ b/Source/Doc/Architecture.md
@@ -1721,6 +1721,7 @@ available along with the registers/information returned.
 |      _Returned Values_
 |           A: Status (0=OK, else error)
 |           DE:HL: Current Timer Tick Count Value
+|           C: Tick frequency (typically 50 or 60)
 
 #### SYSGET Subfunction 0xD1 -- Get Seconds Count (SECONDS)
 
@@ -1806,15 +1807,6 @@ available along with the registers/information used as input.
 |      _Returned Values_
 |           A: Status (0=OK, else error)
 
-#### SYSSET Subfunction 0xD2 -- Inc Timer (TIMER)
-
-|      _Entry Parameters_
-|           BC: 0xF9D2
-
-|      _Returned Values_
-|           A: Status (0=OK, else error)
-
-
 #### SYSSET Subfunction 0xE0 -- Set Boot Information (BOOTINFO)
 
 |      _Entry Parameters_
diff --git a/Source/Doc/GettingStarted.md b/Source/Doc/GettingStarted.md
index dada3943..cd6bc2da 100644
--- a/Source/Doc/GettingStarted.md
+++ b/Source/Doc/GettingStarted.md
@@ -1190,8 +1190,8 @@ these applications are no longer provided.
 driver.
 * Ed Brindley contributed some of the code that supports the RC2014
 platform.
-* Phil Summers contributed Forth and BASIC in ROM as well as a long
-list of general code enhancements.
+* Phil Summers contributed Forth and BASIC in ROM, the AY-3-8910 sound
+driver as well as a long list of general code enhancements.
 * Phillip Stevens contributed support for FreeRTOS.
 * Curt Mayer contributed the Linux / MacOS build process.
 * UNA BIOS and FDISK80 are the products of John Coffman.
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index c51edd4d..fe3303e0 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -2458,6 +2458,7 @@ SYS_GETTIMER:
 	HB_DI
 	CALL	LD32
 	HB_EI
+	LD	C, TICKFREQ
 	XOR	A
 	RET
 ;
diff --git a/Source/HBIOS/hdsk.asm b/Source/HBIOS/hdsk.asm
index a5d3b0ff..e6643dd1 100644
--- a/Source/HBIOS/hdsk.asm
+++ b/Source/HBIOS/hdsk.asm
@@ -27,10 +27,12 @@ HDSK_CFGTBL:
 	.DB	0			; DRIVER DEVICE NUMBER
 	.DB	0			; DEVICE STATUS
 	.DW	0,0			; CURRENT LBA
+#IF (HDSK_DEVCNT >= 2)
 	; DEVICE 1
 	.DB	1			; DEVICE NUMBER
 	.DB	0			; DEVICE STATUS
 	.DW	0,0			; CURRENT LBA
+#ENDIF
 ;
 #IF ($ - HDSK_CFGTBL) != (HDSK_DEVCNT * HDSK_CFGSIZ)
 	.ECHO	"*** INVALID HDSK CONFIG TABLE ***\n"
diff --git a/Source/HBIOS/sn76489.asm b/Source/HBIOS/sn76489.asm
index a59a5b1d..f8181983 100644
--- a/Source/HBIOS/sn76489.asm
+++ b/Source/HBIOS/sn76489.asm
@@ -116,7 +116,7 @@ SN7_VOLUME:
 
 SN7_NOTE:
 	AUDTRACE(SNT_NOTE)
-	AUDTRACE_L
+	AUDTRACE_HL
 	AUDTRACE_CR
 
 	LD	H,0
diff --git a/Source/Images/Build.cmd b/Source/Images/Build.cmd
index 01e52351..c24948a3 100644
--- a/Source/Images/Build.cmd
+++ b/Source/Images/Build.cmd
@@ -21,7 +21,7 @@ call BuildDisk.cmd cpm3 wbw_hd ..\cpm3\cpmldr.sys
 call BuildDisk.cmd zpm3 wbw_hd ..\cpm3\cpmldr.sys
 call BuildDisk.cmd ws4 wbw_hd
 
-if exist ..\BPBIOS\bpbio-ww.rel call BuildHD.cmd bp wbw_hd
+if exist ..\BPBIOS\bpbio-ww.rel call BuildDisk.cmd bp wbw_hd
 
 echo.
 echo Building Combo Disk (legacy format) Image...
@@ -37,9 +37,9 @@ call BuildDisk.cmd cpm3 wbw_hdnew ..\cpm3\cpmldr.sys
 call BuildDisk.cmd zpm3 wbw_hdnew ..\cpm3\cpmldr.sys
 call BuildDisk.cmd ws4 wbw_hdnew
 
-if exist ..\BPBIOS\bpbio-ww.rel call BuildHD.cmd bp wbw_hdnew
+if exist ..\BPBIOS\bpbio-ww.rel call BuildDisk.cmd bp wbw_hdnew
 
-copy hd_prefix.dat ..\..\Binary\
+copy hdnew_prefix.bin ..\..\Binary\
 
 echo.
 echo Building Combo Disk (new format) Image...
diff --git a/Source/Images/Makefile b/Source/Images/Makefile
index ea5a4e63..be90202f 100644
--- a/Source/Images/Makefile
+++ b/Source/Images/Makefile
@@ -15,10 +15,14 @@ HDNEWIMGS = hdnew_cpm22.img hdnew_zsdos.img hdnew_nzcom.img \
 HDPREFIX =
 HDNEWPREFIX = hdnew_prefix.bin
 
-OBJECTS = $(FDIMGS) $(HDIMGS) hd_combo.img $(HDNEWIMGS) hdnew_combo.img
+OBJECTS = $(FDIMGS)
+OBJECTS += $(HDIMGS) hd_combo.img $(HDPREFIX)
+OBJECTS += $(HDNEWIMGS) hdnew_combo.img $(HDNEWPREFIX)
 
 OTHERS = blank144 blankhd blankhdnew
 
+NODELETE = $(HDPREFIX) $(HDNEWPREFIX)
+
 DEST=../../Binary
 
 TOOLS = ../../Tools
@@ -26,10 +30,10 @@ include $(TOOLS)/Makefile.inc
 
 DIFFPATH = $(DIFFTO)/Binary
 
-hd_combo.img:	$(HDPREFIX) $(HDIMGS)
+hd_combo.img: $(HDPREFIX) $(HDIMGS)
 	cat $^ > $@
 
-hdnew_combo.img:	$(HDNEWPREFIX) $(HDNEWIMGS)
+hdnew_combo.img: $(HDNEWPREFIX) $(HDNEWIMGS)
 	cat $^ > $@
 
 #
diff --git a/Source/Makefile b/Source/Makefile
index 63c4204f..3df2bab5 100644
--- a/Source/Makefile
+++ b/Source/Makefile
@@ -9,7 +9,7 @@ SUBDIRS += Fonts
 SUBDIRS += CPM22 ZCPR ZCPR-DJ ZSDOS
 SUBDIRS += HBIOS CPM3
 SUBDIRS += ZPM3
-SUBDIRS += BPBIOS
+#SUBDIRS += BPBIOS
 SUBDIRS += Images
 TOOLS = ../Tools
 include $(TOOLS)/Makefile.inc
diff --git a/Source/Prop/Spin/ParPortProp.spin b/Source/Prop/Spin/ParPortProp.spin
index 6ecf049f..5e890c21 100644
--- a/Source/Prop/Spin/ParPortProp.spin
+++ b/Source/Prop/Spin/ParPortProp.spin
@@ -3,8 +3,8 @@
   ************************************
   *  ParPortProp for RomWBW          *
   *  Interface to RBC ParPortProp    *
-  *  Version 0.96                 *
-  *  March 11, 2018               *
+  *  Version 0.97                    *
+  *  May 9, 2020                     *
   ************************************
 
   Wayne Warthen
@@ -29,11 +29,12 @@
   Updates:
 
     2018-03-11 WBW: Implement character attributes
+    2020-05-09 WBW: Switch monitor refresh to 60Hz
 
 }}
 
 CON
-  VERSION = (((0 << 8) + 96) << 16) + 0
+  VERSION = (((0 << 8) + 97) << 16) + 0
 
   _CLKMODE = XTAL1 + PLL16X
   _XINFREQ = 5_000_000
@@ -608,7 +609,7 @@ PRI Activity
 
 DAT
 
-strVer	byte	"F/W v0.96",0
+strVer	byte	"F/W v0.97",0
 strHW	byte	"ParPortProp",0
 strROM	byte	"RomWBW",0
 
diff --git a/Source/Prop/Spin/PropIO.spin b/Source/Prop/Spin/PropIO.spin
index 3d677264..9e074fe0 100644
--- a/Source/Prop/Spin/PropIO.spin
+++ b/Source/Prop/Spin/PropIO.spin
@@ -3,8 +3,8 @@
   *******************************
   *  PropIO for RomWBW          *
   *  Interface to RBC PropIO    *
-  *  Version 0.96               *
-  *  March 11, 2018             *
+  *  Version 0.97               *
+  *  May 9, 2020                *
   *******************************
 
   Wayne Warthen
@@ -34,11 +34,12 @@
     2014-02-09 WBW: Clean up
     2015-11-15 WBW: Added SD card capacity reporting
     2018-03-11 WBW: Implement character attributes
+    2020-05-09 WBW: Switch monitor refresh to 60Hz
 
 }}
 
 CON
-  VERSION = (((0 << 8) + 96) << 16) + 0
+  VERSION = (((0 << 8) + 97) << 16) + 0
 
   _CLKMODE = XTAL1 + PLL16X
   _XINFREQ = 5_000_000
@@ -337,7 +338,7 @@ PRI DumpBuffer(Buffer) | i, j
 
 DAT
 
-strVer	byte	"F/W v0.96",0
+strVer	byte	"F/W v0.97",0
 strHW	byte	"PropIO",0
 strROM	byte	"RomWBW",0
 
diff --git a/Source/Prop/Spin/PropIO2.spin b/Source/Prop/Spin/PropIO2.spin
index 9e01d3cb..ad1592f7 100644
--- a/Source/Prop/Spin/PropIO2.spin
+++ b/Source/Prop/Spin/PropIO2.spin
@@ -3,8 +3,8 @@
   *********************************
   *  PropIO 2 for RomWBW          *
   *  Interface to RBC PropIO 2    *
-  *  Version 0.96                 *
-  *  March 11, 2018               *
+  *  Version 0.97                 *
+  *  May 9, 2020                  *
   *********************************
 
   Wayne Warthen
@@ -34,11 +34,12 @@
     2014-02-08 WBW: Adaptation for PropIO 2
     2015-11-15 WBW: Added SD card capacity reporting
     2018-03-11 WBW: Implement character attributes
+    2020-05-09 WBW: Switch monitor refresh to 60Hz
 
 }}
 
 CON
-  VERSION = (((0 << 8) + 96) << 16) + 0
+  VERSION = (((0 << 8) + 97) << 16) + 0
 
   _CLKMODE = XTAL1 + PLL16X
   _XINFREQ = 5_000_000
@@ -337,7 +338,7 @@ PRI DumpBuffer(Buffer) | i, j
 
 DAT
 
-strVer	byte	"F/W v0.96",0
+strVer	byte	"F/W v0.97",0
 strHW	byte	"PropIO v2",0
 strROM	byte	"RomWBW",0
 
diff --git a/Source/Prop/Spin/vgacolour.spin b/Source/Prop/Spin/vgacolour.spin
index c5cc2f80..0981fe55 100644
--- a/Source/Prop/Spin/vgacolour.spin
+++ b/Source/Prop/Spin/vgacolour.spin
@@ -20,6 +20,7 @@
 
 CON
 
+{
 ' 640 x 480 @ 69Hz settings: 80 x 30 characters
 
 	hp = 640	' horizontal pixels
@@ -33,6 +34,24 @@ CON
 	hn = 1		' horizontal normal sync state (0|1)
 	vn = 1		' vertical normal sync state (0|1)
 	pr = 30		' pixel rate in MHz at 80MHz system clock (5MHz granularity)
+}
+	
+'{
+' 640 x 480 @ 60Hz settings: 80 x 40 characters
+
+  hp = 640      'horizontal pixels
+  vp = 480      'vertical pixels
+  hf = 16       'horizontal front porch pixels
+  hs = 96       'horizontal sync pixels
+  hb = 48      'horizontal back porch pixels
+  vf = 10        'vertical front porch lines
+  vs = 2        'vertical sync lines
+  vb = 33       'vertical back porch lines
+  hn = 1        'horizontal normal sync state (0|1)
+  vn = 1        'vertical normal sync state (0|1)
+  pr = 25       'pixel rate in MHz at 80MHz system clock (5MHz granularity)
+'}
+
 
 ' columns and rows
 
diff --git a/Source/ver.inc b/Source/ver.inc
index 3cb3dc77..59f55502 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,4 +2,4 @@
 #DEFINE	RMN	1
 #DEFINE	RUP	1
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.1.1-pre.3"
+#DEFINE BIOSVER	"3.1.1-pre.5"
diff --git a/Source/ver.lib b/Source/ver.lib
index 3c226412..33acdafa 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	1
 rup	equ	1
 rtp	equ	0
 biosver	macro
-	db	"3.1.1-pre.3"
+	db	"3.1.1-pre.5"
 	endm