tape autocalibration code is dangerous on 1MHz, disable it for slower machines

STATUS.md

@@ -18,7 +18,7 @@ Here are the features of the Open ROMs not found in the original ROMs from the 8
 * `LIST` command should never damage the screen if trying to list memory content which is not a BASIC program
 * high performance garbage collector
 
-* turbo tape load support (as device 7, or using `←L` / `←M`, optionally with a file name), quite sophisticated: up to 250 blocks (can store bytes under I/O), automatically adjusts for tape speed differences
+* turbo tape load support (as device 7, or using `←L` / `←M`, optionally with a file name), quite sophisticated: up to 250 blocks (can store bytes under I/O), on MEGA65 motherboard automatically adjusts itself for tape speed differences
 * normal tape load error log is limited by free stack space only (no artificial limitation like in original ROMs)
 * tape format autodetection; normal vs turbo is mostly transparent to user
 * improved support for tape adapters (for using regular casette players and other audio devices instead of Datasette) and emulators

src/aliases/,aliases_config.s

@@ -451,6 +451,14 @@
 
 
 
+; Determine if it is OK to include tape autocalibration routines
+
+!ifndef CONFIG_MB_M65 {
+	!set HAS_TAPE_AUTOCALIBRATE = 1
+}
+
+
+
 ; Defines for multi-segment ROMs
 
 !ifdef CONFIG_MB_M65 {

src/aliases/,aliases_ram_lowmem.s

@@ -310,11 +310,14 @@
 
 !ifdef HAS_TAPE {
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
+
 	!addr __normal_time_S             = IRQTMP+0          ; duration of the short pulse
 	!addr __normal_time_M             = IRQTMP+1          ; duration of the medium pulse
 
 	!addr __turbo_half_S              = IRQTMP+0          ; half-duration of the short pulse
 	!addr __turbo_half_L              = IRQTMP+1          ; half-duration of the long pulse
+}
 
 	!addr __pulse_threshold           = SVXT              ; pulse classification threshold
 	!addr __pulse_threshold_ML        = SYNO              ; M/L pulse classification threshold, for normal only

src/kernal/tape/tape_normal_calibrate.s

@@ -10,7 +10,7 @@
 ;
 
 
-!ifdef CONFIG_TAPE_NORMAL {
+!ifdef CONFIG_TAPE_NORMAL { !ifdef HAS_TAPE_AUTOCALIBRATE {
 
 
 tape_normal_calibrate_during_pilot:              ; reecalibration during the pilot
@@ -122,4 +122,4 @@ tape_normal_calibrate_threshold_inc:
 tape_normal_calibrate_done:
 
 	rts
-}
+} }

src/kernal/tape/tape_normal_get_bit.s

@@ -22,13 +22,16 @@ tape_normal_get_bit:
 
 	; First impulse was short, second should be medium
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
 	jsr tape_normal_calibrate_after_S
+}
 
 	jsr tape_common_get_pulse
 	bcs tape_normal_get_bit_error
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
 	jsr tape_normal_calibrate_after_M
-
+}
 	; We have a bit '0'
 
 	lda #$00
@@ -46,13 +49,16 @@ tape_normal_get_bit_1:
 
 	; First impulse was medium, second should be short
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
 	jsr tape_normal_calibrate_after_M
+}
 
 	jsr tape_common_get_pulse
 	bcc tape_normal_get_bit_error
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
 	jsr tape_normal_calibrate_after_S
-
+}
 	; We have a bit '1'
 
 	clc

src/kernal/tape/tape_normal_get_marker.s

@@ -32,16 +32,17 @@ tape_normal_get_marker_type:
 
 	; Not an entry point!!!
 
-tape_normal_get_marker_while_sync_loop:
+tape_normal_get_marker_while_sync__loop:
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
 	jsr tape_normal_calibrate_during_pilot                 ; while sync use short pulses for calibration
-
+}
 	; FALLTROUGH
 
 tape_normal_get_marker_while_sync:
 
 	jsr tape_common_get_pulse
-	bcs tape_normal_get_marker_while_sync_loop             ; branch if short pulse
+	bcs tape_normal_get_marker_while_sync__loop             ; branch if short pulse
 
 	cmp __pulse_threshold_ML
 	bcs tape_normal_get_marker_while_sync                  ; too short for a long pulse

src/kernal/tape/tape_normal_get_pilot.s

@@ -96,8 +96,9 @@ tape_normal_get_pilot_common_loop_inner:
 @1:
 }
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
 	jsr tape_normal_calibrate_during_pilot
-
+}
 	dey
 	bne tape_normal_get_pilot_common_loop_inner
 

src/kernal/tape/tape_turbo_get_bit.s

@@ -19,9 +19,12 @@ tape_turbo_get_bit:
 	jsr tape_common_get_pulse
 	bcs @1
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
+
 	clc
 	ror
 	sta __turbo_half_S                 ; store half of the last measurement result for short pulse
+}
 
 	lda #$01
 !ifdef CONFIG_MB_M65 {
@@ -34,10 +37,15 @@ tape_turbo_get_bit:
 	sta VIC_EXTCOL
 	sec
 	rts
+
 @1:
+
+!ifdef HAS_TAPE_AUTOCALIBRATE {
+
 	clc
 	ror
 	sta __turbo_half_L                 ; store half of the last measurement result for long pulse
+}
 
 	lda #$00
 !ifdef CONFIG_MB_M65 {

src/kernal/tape/tape_turbo_get_byte.s

@@ -27,6 +27,8 @@ tape_turbo_get_byte:
 	bcc @1	                           ; is the initial 1 shifted into carry already?
 	+plx_trash_a
 
+!ifdef HAS_TAPE_AUTOCALIBRATE {
+
 	; Compensate for tape speed variations
 
 	lda __turbo_half_S                 ; half of the last value for bit '0'
@@ -51,6 +53,7 @@ tape_turbo_get_byte:
 	beq tape_turbo_get_byte_done       ; do not increase threshold too far no matter what
 
 	inc __pulse_threshold
+}
 
 tape_turbo_get_byte_done: