changed CPU speed handling for MEGA65

src/kernal/board_m65/mega65_iec_slow_fast.s

@@ -0,0 +1,45 @@
+;; #LAYOUT# M65 KERNAL_0 #TAKE
+;; #LAYOUT# *   *        #IGNORE
+
+;
+; Checks if system is in MEGA65 native mode; if so, switches CPU speed to fast/slow - for IEC routines;
+; Alters only status bits, all remaining registers preserved
+;
+
+!ifdef CONFIG_IEC {
+
+
+m65_iec_slow:
+
+	jsr M65_MODEGET
+	bcs m65_iec_fast_slow_done
+
+	; Switch CPU speed
+
+	pha
+	lda VIC_CTRLB
+	and #%10111111
+	bra m65_iec_fast_slow_common
+
+m65_iec_fast:
+
+	jsr M65_MODEGET
+	bcs m65_iec_fast_slow_done
+
+	pha
+	lda VIC_CTRLB
+	ora #%01000000
+
+	; FALLTROUGH
+
+m65_iec_fast_slow_common:
+
+	sta VIC_CTRLB
+	pla
+
+	; FALLTROUGH
+
+m65_iec_fast_slow_done:
+
+	rts
+}

src/kernal/board_m65/mega65_viciv_init.s

@@ -17,10 +17,10 @@ viciv_init:
 	lda #$00
 	sta MISC_EMU
 
-	; Set misc VIC-IV flags
+	; Set VIC-IV CTRL registers
 
-	lda #%01000000  ; enable C65 character set
-	sta VIC_CTRLA
+	lda #%01000000                     ; enable C65 character set
+	jsr mega65_viciv_setctrl_AC        ; also initialize remaining CTRLA / CTRLC bits; CTRLB will be set by screen editor
 
 	; Disable hot registers
 

src/kernal/board_m65/mega65_viciv_setctrl_AC.s

@@ -0,0 +1,18 @@
+;; #LAYOUT# M65 KERNAL_0 #TAKE
+;; #LAYOUT# *   *        #IGNORE
+
+;
+; Helper routine for setting VIC-IV control registers A and C
+;
+
+
+mega65_viciv_setctrl_AC:
+
+	sta VIC_CTRLA
+
+	lda VIC_CTRLC
+	and #%01101000
+	ora #%01000000  ; make C65/C128 fast modes switch to max MEGA65 CPU speed
+	sta VIC_CTRLC
+
+	rts

src/kernal/board_m65/mega65_viciv_shutdown.s

@@ -20,12 +20,8 @@ viciv_shutdown:
 	; Set misc VIC-IV flags
 
 	lda #%00000000
-	sta VIC_CTRLA  ; enable C64 character set
-	sta VIC_CTRLB  ; disable extended resolution and attributes
-
-	lda VIC_CTRLC
-	and #%00101000 ; disable fast mode and various VIC-IV extensions
-	sta VIC_CTRLC
+	sta VIC_CTRLB                      ; disable extended resolution and attributes, disable 3.5 MHz mode
+	jsr mega65_viciv_setctrl_AC        ; enable C64 character set, initialize remaining CTRLA / CTRLC bits
 
 	; Reenable hot registers