From c29b1061dca030cdcbf50ca59ea425980896cd11 Mon Sep 17 00:00:00 2001
From: Jeff Parsons <Jeff@pcjs.org>
Date: Sun, 7 Jun 2015 23:33:22 -0700
Subject: [PATCH] Start debugging HDC failure on DeskPro 386 configuration

---
 blog/2015/06/05/README.md                              |  7 ++++---
 .../machine/compaq/deskpro386/vga/2048kb/machine.xml   |  2 +-
 modules/pcjs/lib/video.js                              | 10 ++++++++--
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/blog/2015/06/05/README.md b/blog/2015/06/05/README.md
index c73e9f58f..1dcacf0c9 100644
--- a/blog/2015/06/05/README.md
+++ b/blog/2015/06/05/README.md
@@ -14,15 +14,16 @@ For example, when I ran this code:
     0CE0:0106  
     -g
 
-the following "text" appeared at the top of the screen, in 640x200 16-color graphics mode 0x0E:
+the following "text" correctly appeared at the top of the screen, in 640x200 16-color graphics mode 0x0E:
 
     AX=0B01  BX=0000  CX=0000  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000  
     DS=0CE0  ES=0CE0  SS=0CE0  CS=0CE0  IP=0105   NV UP EI PL NZ NA PO NC 
     0CE0:0105 CC            INT     3                                  
     -
 
-When I typed "q", then "cls" and finally "dir", the screen filled with DOS directory contents.  But as
-soon as the screen started to scroll, the screen contents became garbled.  Other EGA graphics modes,
+And when I typed "q", then "cls" and finally "dir", the screen filled with DOS directory contents.
+
+But as soon as the screen started to scroll, the screen contents became garbled.  Other EGA graphics modes,
 like 640x350 16-color mode 0x10, didn't have this problem.
 
 To investigate, I set a breakpoint in the IBM EGA ROM where the scrolling starts, at 0xC000:12EA (see p.130 of the
diff --git a/devices/pc/machine/compaq/deskpro386/vga/2048kb/machine.xml b/devices/pc/machine/compaq/deskpro386/vga/2048kb/machine.xml
index 1a50a8cb3..27af7e1f9 100644
--- a/devices/pc/machine/compaq/deskpro386/vga/2048kb/machine.xml
+++ b/devices/pc/machine/compaq/deskpro386/vga/2048kb/machine.xml
@@ -13,7 +13,7 @@
 	<debugger id="debugger" messages="fault|port" commands=""/>
 	<panel ref="/devices/pc/panel/btpanel.xml"/>
 	<fdc ref="/disks/pc/library.xml" width="340px" automount='{A: {name: "PC-DOS 3.00 (Disk 1)", path: "/disks/pc/dos/ibm/3.00/PCDOS300-DISK1.json"}, B: {name: "PC-DOS 3.00 (Disk 2)", path: "/disks/pc/dos/ibm/3.00/PCDOS300-DISK2.json"}}'/>
-	<hdcFoo id="hdcAT" type="at" drives='[{name:"20Mb Hard Disk",type:2}]'/>
+	<hdc id="hdcAT" type="at" drives='[{name:"20Mb Hard Disk",type:2}]'/>
 	<chipset id="chipset" model="deskpro386" floppies="[1200,1200]" monitor="vga"/>
 	<serial id="com1" adapter="1"/>
 	<serial id="com2" adapter="2" binding="print"/>
diff --git a/modules/pcjs/lib/video.js b/modules/pcjs/lib/video.js
index 901a9dbdc..6e3c4c768 100644
--- a/modules/pcjs/lib/video.js
+++ b/modules/pcjs/lib/video.js
@@ -2320,7 +2320,10 @@ Card.prototype.setMemoryAccess = function(nAccess)
         var nReadAccess = nAccess & Card.ACCESS.READ.MASK;
         var fnReadByte = Card.ACCESS.afn[nReadAccess];
         if (!fnReadByte) {
-            if (DEBUG && this.dbg) this.dbg.message("Card.setMemoryAccess(" + str.toHexWord(nAccess) + "): missing readByte handler");
+            if (DEBUG && this.dbg) {
+                this.dbg.message("Card.setMemoryAccess(" + str.toHexWord(nAccess) + "): missing readByte handler");
+                this.dbg.stopCPU();     // let's take a look
+            }
             if (nReadAccess & Card.ACCESS.READ.EVENODD) {
                 fnReadByte = Card.ACCESS.afn[Card.ACCESS.READ.EVENODD];
             }
@@ -2328,7 +2331,10 @@ Card.prototype.setMemoryAccess = function(nAccess)
         var nWriteAccess = nAccess & Card.ACCESS.WRITE.MASK;
         var fnWriteByte = Card.ACCESS.afn[nWriteAccess];
         if (!fnWriteByte) {
-            if (DEBUG && this.dbg) this.dbg.message("Card.setMemoryAccess(" + str.toHexWord(nAccess) + "): missing writeByte handler");
+            if (DEBUG && this.dbg) {
+                this.dbg.message("Card.setMemoryAccess(" + str.toHexWord(nAccess) + "): missing writeByte handler");
+                this.dbg.stopCPU();     // let's take a look
+            }
             if (nWriteAccess & Card.ACCESS.WRITE.EVENODD) {
                 fnWriteByte = Card.ACCESS.afn[Card.ACCESS.WRITE.EVENODD];
             }