diff --git a/SourceGen/RuntimeData/Apple/C08x-DiskII.sym65 b/SourceGen/RuntimeData/Apple/C08x-DiskII.sym65
new file mode 100644
index 0000000..3863c4c
--- /dev/null
+++ b/SourceGen/RuntimeData/Apple/C08x-DiskII.sym65
@@ -0,0 +1,35 @@
+; Copyright 2018 faddenSoft. All Rights Reserved.
+; See the LICENSE.txt file for distribution terms (Apache 2.0).
+;
+; Sources:
+;   Various Apple II reference materials found online
+
+*SYNOPSIS C08x I/O locations for the Disk ][
+
+; Disk ][ I/O base address locations.
+;
+; A few things hard-code slot 6 for disk access, in which case addresses
+; like $C0E8 will work here.  It's far more common for code to use indexed
+; addressing like "LDA $C088,X", which clashes with the slot 0
+; definitions for the language card.  SourceGen doesn't distinguish
+; between direct and indexed access to a location when resolving platform
+; symbols, so you can have one or the other.
+;
+; Other peripherals may use a similar system of indexing, so it's useful
+; to have each in a separate file.
+IWM_PH0_OFF     @ $C080     ;IWM phase 0 off
+IWM_PH0_ON      @ $C081     ;IWM phase 0 on
+IWM_PH1_OFF     @ $C082     ;IWM phase 1 off
+IWM_PH1_ON      @ $C083     ;IWM phase 1 on
+IWM_PH2_OFF     @ $C084     ;IWM phase 2 off
+IWM_PH2_ON      @ $C085     ;IWM phase 2 on
+IWM_PH3_OFF     @ $C086     ;IWM phase 3 off
+IWM_PH3_ON      @ $C087     ;IWM phase 3 on
+IWM_MOTOR_OFF   @ $C088     ;IWM motor off
+IWM_MOTOR_ON    @ $C089     ;IWM motor on
+IWM_DRIVE_1     @ $C08A     ;IWM select drive 1
+IWM_DRIVE_2     @ $C08B     ;IWM select drive 2
+IWM_Q6_OFF      @ $C08C     ;IWM read
+IWM_Q6_ON       @ $C08D     ;IWM WP-sense
+IWM_Q7_OFF      @ $C08E     ;IWM WP-sense/read
+IWM_Q7_ON       @ $C08F     ;IWM write
diff --git a/SourceGen/RuntimeData/Apple/Cxxx-IO.sym65 b/SourceGen/RuntimeData/Apple/Cxxx-IO.sym65
index 33c546e..6c568c0 100644
--- a/SourceGen/RuntimeData/Apple/Cxxx-IO.sym65
+++ b/SourceGen/RuntimeData/Apple/Cxxx-IO.sym65
@@ -137,30 +137,6 @@ LCBANK1         @ $C08B     ;RWx2 read/write RAM bank 1
 
 CLRROM          @ $CFFF     ;disable slot C8 ROM
 
-; Disk ][ I/O locations.
-;
-; A few things hard-code slot 6 for disk access, in which case addresses
-; like $C0E8 will work here.  It's far more common for code to use indexed
-; addressing like "LDA $C088,X", which clashes with the slot 0
-; definitions.  We define these symbols as constants so they're not
-; applied automatically but are available for use.
-IWM_PH0_OFF     = $C080     ;IWM phase 0 off
-IWM_PH0_ON      = $C081     ;IWM phase 0 on
-IWM_PH1_OFF     = $C082     ;IWM phase 1 off
-IWM_PH1_ON      = $C083     ;IWM phase 1 on
-IWM_PH2_OFF     = $C084     ;IWM phase 2 off
-IWM_PH2_ON      = $C085     ;IWM phase 2 on
-IWM_PH3_OFF     = $C086     ;IWM phase 3 off
-IWM_PH3_ON      = $C087     ;IWM phase 3 on
-IWM_MOTOR_OFF   = $C088     ;IWM motor off
-IWM_MOTOR_ON    = $C089     ;IWM motor on
-IWM_DRIVE_1     = $C08A     ;IWM select drive 1
-IWM_DRIVE_2     = $C08B     ;IWM select drive 2
-IWM_Q6_OFF      = $C08C     ;IWM read
-IWM_Q6_ON       = $C08D     ;IWM WP-sense
-IWM_Q7_OFF      = $C08E     ;IWM WP-sense/read
-IWM_Q7_ON       = $C08F     ;IWM write
-
 
 ; Not strictly I/O locations, but they're in the neighborhood.
 ROM_AUXMOVE     @ $C311
diff --git a/SourceGen/RuntimeData/SystemDefs.json b/SourceGen/RuntimeData/SystemDefs.json
index 28b8592..2dc8543 100644
--- a/SourceGen/RuntimeData/SystemDefs.json
+++ b/SourceGen/RuntimeData/SystemDefs.json
@@ -12,6 +12,7 @@
       "SymbolFiles" : [
         "RT:Apple/F8-ROM.sym65",
         "RT:Apple/Cxxx-IO.sym65",
+        "RT:Apple/C08x-DiskII.sym65",
         "RT:Apple/ProDOS8.sym65"
       ],
       "ExtensionScripts" : [
@@ -31,6 +32,7 @@
       "SymbolFiles" : [
         "RT:Apple/F8-ROM.sym65",
         "RT:Apple/Cxxx-IO.sym65",
+        "RT:Apple/C08x-DiskII.sym65",
         "RT:Apple/DOS33.sym65"
       ],
       "ExtensionScripts" : [
@@ -49,6 +51,7 @@
       "SymbolFiles" : [
         "RT:Apple/F8-ROM.sym65",
         "RT:Apple/Cxxx-IO.sym65",
+        "RT:Apple/C08x-DiskII.sym65",
         "RT:Apple/ProDOS8.sym65",
         "RT:Apple/IIgs-ROM.sym65"
       ],
@@ -69,6 +72,7 @@
       "Description" : "Apple IIgs, configured for GS/OS.",
       "SymbolFiles" : [
         "RT:Apple/Cxxx-IO.sym65",
+        "RT:Apple/C08x-DiskII.sym65",
         "RT:Apple/IIgs-ROM.sym65",
         "RT:Apple/GSOS.sym65"
       ],