diff --git a/Source/HBIOS/Config/RCEZ80_std.asm b/Source/HBIOS/Config/RCEZ80_std.asm
index 3f178e68..e71a921f 100644
--- a/Source/HBIOS/Config/RCEZ80_std.asm
+++ b/Source/HBIOS/Config/RCEZ80_std.asm
@@ -67,3 +67,5 @@ PRPENABLE	.SET	FALSE		; PRP: ENABLE ECB PROPELLER IO BOARD DRIVER (PRP.ASM)
 EZ80UARTENABLE	.SET	TRUE		; EZ80 UART: ENABLE EZ80 UART0 DRIVER (EZ80UART.ASM)
 EZ80RTCENABLE	.SET	TRUE		; EZ80 ON CHIP RTC
 EZ80TIMER	.SET	EZ80TMR_INT	; EZ80: TIMER TICK MODEL: EZ80TMR_[INT|FIRM]
+;
+CHENABLE	.EQU	FALSE		; CH: ENABLE CH375/376 USB SUPPORT
diff --git a/Source/HBIOS/cfg_rcez80.asm b/Source/HBIOS/cfg_rcez80.asm
index 0ab3f277..45a0a9d8 100644
--- a/Source/HBIOS/cfg_rcez80.asm
+++ b/Source/HBIOS/cfg_rcez80.asm
@@ -47,10 +47,12 @@ MPGENA		.EQU	$7C		; Z2 MEM MGR PAGING ENABLE REGISTER (BIT 0, WRITE ONLY)
 ; BUS TIMING FOR PAGED MEMORY ACCESS (CS3)
 EZ80_MEM_CYCLES	.EQU	3		; EZ80 CYCLES FOR MEMORY (1-15)
 EZ80_MEM_FREQ	.EQU	16000		; CALCULATE APPROPRIATE BUS CYCLES TO ACHIVE APPOX BUS FREQUENCY
+EZ80_MEM_MINCYC	.EQU	1		; EZ80 MINIMUM CYCLES FOR MEMORY WHEN CALCULATING FROM EZ80_MEM_FREQ
 ;
 ; BUS TIMING FOR EXTERNAL I/O ACCESS (CS2)
 EZ80_IO_CYCLES	.EQU	4		; EZ80 CYCLES FOR IO (1-15)
 EZ80_IO_FREQ	.EQU	5250		; CALCULATE APPROPRIATE BUS CYCLES TO ACHIVE APPOX BUS FREQUENCY
+EZ80_IO_MINCYC	.EQU	4		; EZ80 MINIMUM CYCLES FOR IO WHEN CALCULATING FROM EZ80_IO_FREQ
 ;
 ; SELECT CYCLES, OR CALCULATE CYCLES BASED ON DESIRED FREQUENCY
 EZ80_ASSIGN	.EQU	0		; 0 -> USE FREQ, 1 -> USE CYCLES
diff --git a/Source/HBIOS/ez80cpudrv.asm b/Source/HBIOS/ez80cpudrv.asm
index 1570cdab..13af3f4c 100644
--- a/Source/HBIOS/ez80cpudrv.asm
+++ b/Source/HBIOS/ez80cpudrv.asm
@@ -44,7 +44,10 @@ EZ80_PREINIT:
 #ELSE
 	LD	HL, EZ80_MEM_FREQ
 	LD	DE, EZ80_IO_FREQ
-	EZ80_UTIL_SET_BUSFQ()		; H -> CS3 CYCLES, L -> CS2 CYCLES
+	EXX
+	LD	HL, EZ80_MEM_MINCYC << 8 | EZ80_IO_MINCYC
+	EXX
+	EZ80_UTIL_SET_BUSFQ()
 #ENDIF
 	LD	A, H
 	LD	(EZ80_PLT_C3CYL), A