diff --git a/Source/HBIOS/sd.asm b/Source/HBIOS/sd.asm
index 1bd0f951..e81baf5d 100644
--- a/Source/HBIOS/sd.asm
+++ b/Source/HBIOS/sd.asm
@@ -1742,26 +1742,32 @@ SD_SELECT:
 ;	CALL	SD_WAITTX
 ;#ENDIF
 ;
+#IF (SDMODE == SDMODE_SC)
 	LD	A,(IY+SD_DEV)		; GET CURRENT DEVICE
 	OR	A			; SET FLAGS
 	LD	A,(SD_OPRVAL)		; GET CURRENT OPRVAL BACK
 	JR	NZ,SD_SELECT1		; IF NOT ZERO, DO SECONDARY
 	; ASSERT PRIMARY CS, DEASSERT SECONDARY (IF ANY)
 	OR	SD_CS0
-#IF (SD_DEVCNT > 1)
+  #IF (SD_DEVCNT > 1)
 	AND	~SD_CS1
-#ENDIF
+  #ENDIF
 	JR	SD_SELECT2
 SD_SELECT1:
 	; DEASSERT PRIMARY CS, ASSERT SECONDARY (IF ANY)
 	AND	~SD_CS0
-#IF (SD_DEVCNT > 1)
+  #IF (SD_DEVCNT > 1)
 	OR	SD_CS1
+  #ENDIF
+#ELSE
+	LD	A,(SD_OPRVAL)		; GET CURRENT OPRVAL BACK
+	OR	SD_CS0
 #ENDIF
+;
 SD_SELECT2:
 ; ADJUST BIT(S) FOR INTERFACES USING INVERTED CS BITS
 #IF ((SDMODE == SDMODE_PPI) | (SDMODE == SDMODE_UART) | (SDMODE == SDMODE_SC))
-  #IF (SD_DEVCNT > 1)
+  #IF ((SDMODE == SDMODE_SC) & (SD_DEVCNT > 1))
 	XOR	SD_CS0 | SD_CS1
   #ELSE
 	XOR	SD_CS0
@@ -1794,14 +1800,14 @@ SD_DESELECT:
 #ENDIF
 ;
 	LD	A,(SD_OPRVAL)
-#IF (SD_DEVCNT > 1)
+#IF ((SDMODE == SDMODE_SC) & (SD_DEVCNT > 1))
 	AND	~(SD_CS0 | SD_CS1)
 #ELSE
 	AND	~SD_CS0
 #ENDIF
 ; ADJUST BIT(S) FOR INTERFACES USING INVERTED CS BITS
 #IF ((SDMODE == SDMODE_PPI) | (SDMODE == SDMODE_UART) | (SDMODE == SDMODE_SC))
-  #IF (SD_DEVCNT > 1)
+  #IF ((SDMODE == SDMODE_SC) & (SD_DEVCNT > 1))
 	XOR	SD_CS0 | SD_CS1
   #ELSE
 	XOR	SD_CS0
diff --git a/Source/Images/Common/All/ZMRX.COM b/Source/Images/Common/All/ZMRX.COM
new file mode 100644
index 00000000..6a5286af
Binary files /dev/null and b/Source/Images/Common/All/ZMRX.COM differ
diff --git a/Source/Images/Common/All/ZMTX.COM b/Source/Images/Common/All/ZMTX.COM
new file mode 100644
index 00000000..8d6d85bb
Binary files /dev/null and b/Source/Images/Common/All/ZMTX.COM differ
diff --git a/Source/ver.inc b/Source/ver.inc
index 5a9f50a1..eff51670 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.137"
+#DEFINE BIOSVER	"3.1.1-pre.138"
diff --git a/Source/ver.lib b/Source/ver.lib
index 96a49209..ef0d476e 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.137"
+	db	"3.1.1-pre.138"
 	endm