diff --git a/Source/HBIOS/cfg_rcez80.asm b/Source/HBIOS/cfg_rcez80.asm
index 900bde81..5beab79f 100644
--- a/Source/HBIOS/cfg_rcez80.asm
+++ b/Source/HBIOS/cfg_rcez80.asm
@@ -263,9 +263,9 @@ SDCSIOFAST	.EQU	FALSE		; SD: ENABLE TABLE-DRIVEN BIT INVERTER IN CSIO MODE
 SDMTSWAP	.EQU	FALSE		; SD: SWAP THE LOGICAL ORDER OF THE SPI PORTS OF THE MT011
 ;
 CHENABLE	.EQU	TRUE		; CH: ENABLE CH375/376 USB SUPPORT
-CHTRACE		.EQU	2		; CH: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
-CHUSBTRACE	.EQU	2		; CHUSB: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
-CHSDTRACE	.EQU	2		; CHSD: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
+CHTRACE		.EQU	1		; CH: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
+CHUSBTRACE	.EQU	1		; CHUSB: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
+CHSDTRACE	.EQU	1		; CHSD: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
 CHCNT		.EQU	1		; CH: NUMBER OF BOARDS TO DETECT (1-2)
 CH0BASE		.EQU	$88		; CH 0: BASE I/O ADDRESS
 CH0USBENABLE	.EQU	TRUE		; CH 0: ENABLE USB DISK
diff --git a/Source/HBIOS/cfg_rcz80.asm b/Source/HBIOS/cfg_rcz80.asm
index ba3ae249..a3069384 100644
--- a/Source/HBIOS/cfg_rcz80.asm
+++ b/Source/HBIOS/cfg_rcz80.asm
@@ -261,12 +261,12 @@ CHENABLE	.EQU	TRUE		; CH: ENABLE CH375/376 USB SUPPORT
 CHTRACE		.EQU	1		; CH: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
 CHUSBTRACE	.EQU	1		; CHUSB: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
 CHSDTRACE	.EQU	1		; CHSD: TRACE LEVEL (0=NO,1=ERRORS,2=ALL)
-CHCNT		.EQU	2		; CH: NUMBER OF BOARDS TO DETECT (1-2)
-CH0BASE		.EQU	$3E		; CH 0: BASE I/O ADDRESS
+CHCNT		.EQU	1		; CH: NUMBER OF BOARDS TO DETECT (1-2)
+CH0BASE		.EQU	$88		; CH 0: BASE I/O ADDRESS
 CH0USBENABLE	.EQU	TRUE		; CH 0: ENABLE USB DISK
 CH0SDENABLE	.EQU	FALSE		; CH 0: ENABLE SD DISK
 CH1BASE		.EQU	$3C		; CH 1: BASE I/O ADDRESS
-CH1USBENABLE	.EQU	TRUE		; CH 1: ENABLE USB DISK
+CH1USBENABLE	.EQU	FALSE		; CH 1: ENABLE USB DISK
 CH1SDENABLE	.EQU	FALSE		; CH 1: ENABLE SD DISK
 ;
 PRPENABLE	.EQU	FALSE		; PRP: ENABLE ECB PROPELLER IO BOARD DRIVER (PRP.ASM)
diff --git a/Source/HBIOS/chsd.asm b/Source/HBIOS/chsd.asm
index e1a7e81d..2b217b80 100644
--- a/Source/HBIOS/chsd.asm
+++ b/Source/HBIOS/chsd.asm
@@ -19,7 +19,7 @@
 ;
 #DEFINE	CHSD_IMGFILE "DISK.IMG"
 ;
-CHSD_FASTIO	.EQU	TRUE		; USE INIR/OTIR?
+CHSD_FASTIO	.EQU	FALSE		; USE INIR/OTIR?
 ;
 ; CHUSB DEVICE STATUS
 ;
diff --git a/Source/HBIOS/chusb.asm b/Source/HBIOS/chusb.asm
index 175a00b2..d77f3f64 100644
--- a/Source/HBIOS/chusb.asm
+++ b/Source/HBIOS/chusb.asm
@@ -196,6 +196,7 @@ CHUSB_READ1:
 	PUSH	BC			; SAVE LOOP CONTROL
 	LD	B,64			; READ 64 BYTES
 	LD	C,(IY+CH_IOBASE)	; BASE PORT
+	EZ80_IO
 	INIR				; DO IT FAST
 	POP	BC			; RESTORE LOOP CONTROL
 #ELSE
@@ -260,6 +261,7 @@ CHUSB_WRITE1:
 	PUSH	BC			; SAVE LOOP CONTROL
 	LD	B,64			; WRITE 64 BYTES
 	LD	C,(IY+CH_IOBASE)	; BASE PORT
+	EZ80_IO
 	OTIR				; DO IT FAST
 	POP	BC			; RESTORE LOOP CONTROL
 #ELSE