diff --git a/Visual Studio Projects/AltairZ80.vcproj b/Visual Studio Projects/AltairZ80.vcproj
index 139e1109..92a5dfbf 100644
--- a/Visual Studio Projects/AltairZ80.vcproj	
+++ b/Visual Studio Projects/AltairZ80.vcproj	
@@ -42,7 +42,7 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories="./;../;../AltairZ80/"
-				PreprocessorDefinitions="NO_INLINE;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID"
+				PreprocessorDefinitions="USE_SIM_IMD;NO_INLINE;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID"
 				MinimalRebuild="true"
 				BasicRuntimeChecks="3"
 				RuntimeLibrary="1"
@@ -121,7 +121,7 @@
 				InlineFunctionExpansion="1"
 				OmitFramePointers="true"
 				AdditionalIncludeDirectories="./;../;../AltairZ80/"
-				PreprocessorDefinitions="NO_INLINE;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID"
+				PreprocessorDefinitions="USE_SIM_IMD;NO_INLINE;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID"
 				StringPooling="true"
 				RuntimeLibrary="0"
 				EnableFunctionLevelLinking="true"
@@ -201,41 +201,6 @@
 				RelativePath="..\AltairZ80\altairz80_mhdsk.c"
 				>
 			</File>
-			<File
-				RelativePath="..\AltairZ80\m68kcpu.c"
-				>
-			</File>
-            
-			<File
-				RelativePath="..\AltairZ80\m68kdasm.c"
-				>
-			</File>
-            
-			<File
-				RelativePath="..\AltairZ80\m68kopac.c"
-				>
-			</File>
-            
-			<File
-				RelativePath="..\AltairZ80\m68kopdm.c"
-				>
-			</File>
-            
-			<File
-				RelativePath="..\AltairZ80\m68kopnz.c"
-				>
-			</File>
-            
-			<File
-				RelativePath="..\AltairZ80\m68kops.c"
-				>
-			</File>
-            
-			<File
-				RelativePath="..\AltairZ80\m68ksim.c"
-				>
-			</File>
-            
 			<File
 				RelativePath="..\AltairZ80\altairz80_net.c"
 				>
@@ -276,6 +241,34 @@
 				RelativePath="..\AltairZ80\insnsd.c"
 				>
 			</File>
+			<File
+				RelativePath="..\AltairZ80\m68kcpu.c"
+				>
+			</File>
+			<File
+				RelativePath="..\AltairZ80\m68kdasm.c"
+				>
+			</File>
+			<File
+				RelativePath="..\AltairZ80\m68kopac.c"
+				>
+			</File>
+			<File
+				RelativePath="..\AltairZ80\m68kopdm.c"
+				>
+			</File>
+			<File
+				RelativePath="..\AltairZ80\m68kopnz.c"
+				>
+			</File>
+			<File
+				RelativePath="..\AltairZ80\m68kops.c"
+				>
+			</File>
+			<File
+				RelativePath="..\AltairZ80\m68ksim.c"
+				>
+			</File>
 			<File
 				RelativePath="..\AltairZ80\mfdc.c"
 				>
@@ -357,7 +350,7 @@
 				>
 			</File>
 			<File
-				RelativePath="..\AltairZ80\sim_imd.c"
+				RelativePath="..\sim_imd.c"
 				>
 			</File>
 			<File
@@ -421,6 +414,10 @@
 				RelativePath="..\sim_fio.h"
 				>
 			</File>
+			<File
+				RelativePath="..\sim_imd.h"
+				>
+			</File>
 			<File
 				RelativePath="..\sim_rev.h"
 				>
diff --git a/descrip.mms b/descrip.mms
index 5b68013b..03b0a085 100644
--- a/descrip.mms
+++ b/descrip.mms
@@ -327,14 +327,14 @@ ALTAIRZ80_SOURCE2 = $(ALTAIRZ80_DIR)S100_DISK1A.C,$(ALTAIRZ80_DIR)S100_DISK2.C,\
                     $(ALTAIRZ80_DIR)S100_FIF.C,$(ALTAIRZ80_DIR)S100_MDRIVEH.C,\
                     $(ALTAIRZ80_DIR)S100_MDSAD.C,$(ALTAIRZ80_DIR)S100_SELCHAN.C,\
                     $(ALTAIRZ80_DIR)S100_SS1.C,$(ALTAIRZ80_DIR)S100_64FDC.C,\
-                    $(ALTAIRZ80_DIR)S100_SCP300F.C,$(ALTAIRZ80_DIR)SIM_IMD.C,\
+                    $(ALTAIRZ80_DIR)S100_SCP300F.C,$(SIMH_DIR)SIM_IMD.C,\
                     $(ALTAIRZ80_DIR)WD179X.C,$(ALTAIRZ80_DIR)S100_DISK3.C,\
                     $(ALTAIRZ80_DIR)S100_ADCS6.C,$(ALTAIRZ80_DIR)S100_HDC1001.C,\
                     $(ALTAIRZ80_DIR)S100_IF3.C,$(ALTAIRZ80_DIR)ALTAIRZ80_MHDSK.C,\
                     $(ALTAIRZ80_DIR)M68KCPU.C,$(ALTAIRZ80_DIR)M68KDASM.C,\
                     $(ALTAIRZ80_DIR)M68KOPAC.C,$(ALTAIRZ80_DIR)M68KOPDM.C,\
                     $(ALTAIRZ80_DIR)M68KOPNZ.C,$(ALTAIRZ80_DIR)M68KOPS.C,$(ALTAIRZ80_DIR)M68KSIM.C
-ALTAIRZ80_OPTIONS = /INCL=($(SIMH_DIR),$(ALTAIRZ80_DIR))/DEF=($(CC_DEFS))
+ALTAIRZ80_OPTIONS = /INCL=($(SIMH_DIR),$(ALTAIRZ80_DIR))/DEF=($(CC_DEFS),"USE_SIM_IMD=1")
 
 #
 # Data General Nova Simulator Definitions.
diff --git a/makefile b/makefile
index aeb4a321..12135e16 100644
--- a/makefile
+++ b/makefile
@@ -768,7 +768,7 @@ LDFLAGS := $(OS_LDFLAGS) $(NETWORK_LDFLAGS) $(LDFLAGS_O)
 BIN = BIN/
 SIM = scp.c sim_console.c sim_fio.c sim_timer.c sim_sock.c \
 	sim_tmxr.c sim_ether.c sim_tape.c sim_disk.c sim_serial.c \
-	sim_video.c
+	sim_video.c sim_imd.c
 
 DISPLAYD = display
 ifeq ($(WIN32),)
@@ -1057,13 +1057,13 @@ ALTAIRZ80 = ${ALTAIRZ80D}/altairz80_cpu.c ${ALTAIRZ80D}/altairz80_cpu_nommu.c \
 	${ALTAIRZ80D}/s100_fif.c ${ALTAIRZ80D}/s100_mdriveh.c \
 	${ALTAIRZ80D}/s100_mdsad.c ${ALTAIRZ80D}/s100_selchan.c \
 	${ALTAIRZ80D}/s100_ss1.c ${ALTAIRZ80D}/s100_64fdc.c \
-	${ALTAIRZ80D}/s100_scp300f.c ${ALTAIRZ80D}/sim_imd.c \
+	${ALTAIRZ80D}/s100_scp300f.c \
 	${ALTAIRZ80D}/wd179x.c ${ALTAIRZ80D}/s100_hdc1001.c \
 	${ALTAIRZ80D}/s100_if3.c ${ALTAIRZ80D}/s100_adcs6.c \
 	${ALTAIRZ80D}/m68kcpu.c ${ALTAIRZ80D}/m68kdasm.c \
 	${ALTAIRZ80D}/m68kopac.c ${ALTAIRZ80D}/m68kopdm.c \
 	${ALTAIRZ80D}/m68kopnz.c ${ALTAIRZ80D}/m68kops.c ${ALTAIRZ80D}/m68ksim.c
-ALTAIRZ80_OPT = -I ${ALTAIRZ80D}
+ALTAIRZ80_OPT = -I ${ALTAIRZ80D} -DUSE_SIM_IMD
 
 
 GRID = GRI
diff --git a/AltairZ80/sim_imd.c b/sim_imd.c
similarity index 97%
rename from AltairZ80/sim_imd.c
rename to sim_imd.c
index b44d149e..71a8c919 100644
--- a/AltairZ80/sim_imd.c
+++ b/sim_imd.c
@@ -301,6 +301,7 @@ static t_stat diskParse(DISK_INFO *myDisk, uint32 isVerbose)
     sim_debug(myDisk->debugmask, myDisk->device, "Processed %d sectors\n", TotalSectorCount);
 
     for(i=0;i<myDisk->ntracks;i++) {
+        uint8 j;
         sim_debug(myDisk->verbosedebugmask, myDisk->device, "Track %02d: ", i);
         for(j=0;j<imd.nsects;j++) {
             sim_debug(myDisk->verbosedebugmask, myDisk->device, "0x%06x ", myDisk->track[i][0].sectorOffsetMap[j]);
diff --git a/AltairZ80/sim_imd.h b/sim_imd.h
similarity index 100%
rename from AltairZ80/sim_imd.h
rename to sim_imd.h