tape interlock support, don't display PRESS PLAY if already pressed

STATUS.md

@@ -151,8 +151,8 @@ NOTE: Even the 'DONE' routines won't support features described as missing in on
 | `$FFF0`   | `$E50A`    | `PLOT`      | DONE     |                                                      |
 | `$FFF3`   |            | `IOBASE`    | DONE     |                                                      |
 | `($FFFA)` |            | NMI vec     | PARTIAL  |                                                      |
-| `($FFFC)` | `$FCE2`    | RESET vec   | PARTIAL  |                                                      |
+| `($FFFC)` | `$FCE2`    | RESET vec   | PARTIAL  | see IOINIT status                                    |
-| `($FFFE)` |            | IRQ/BRK vec | PARTIAL  |                                                      |
+| `($FFFE)` |            | IRQ/BRK vec | DONE     |                                                      |
 
 <br />
 

c64/aliases/,aliases_ram_lowmem.s

@@ -138,7 +138,7 @@
 	.label ROPRTY    = $BD  //          tape / RS-232 temporary storage
 	.label FSBLK     = $BE  //          -- NOT IMPLEMENTED --
 	.label MYCH      = $BF  //          -- NOT IMPLEMENTED --
-	.label CAS1      = $C0  //          -- NOT IMPLEMENTED --
+	.label CAS1      = $C0  //          tape motor interlock
 	.label STAL      = $C1  // $C1-$C2  LOAD/SAVE start address
 	.label MEMUSS    = $C3  // $C3-$C4  temporary address for tape LOAD/SAVE
 	.label LSTX      = $C5  //          last keyy matrix position [!] our usage probably differs in details

c64/kernal/interrupts/ea31.default_irq_handler.s

@@ -5,6 +5,27 @@ default_irq_handler:
 	jsr JSCNKEY
 	jsr JUDTIM // update jiffy clock
 
+#if CONFIG_TAPE_NORMAL || CONFIG_TAPE_TURBO
+
+	// Turn tape motor on/off depending on the button state
+	// For CAS1 (tape motor interlock) variable description, see Mapping the C64, page 7
+
+	lda CPU_R6510
+	and #$10
+	beq !+                             // branch if tape button pressed
+
+	jsr tape_motor_off
+	lda #$00
+	sta CAS1
+	beq default_irq_handler_end_tape   // branch always
+!:
+	lda CAS1
+	bne default_irq_handler_end_tape
+	jsr tape_motor_on
+
+default_irq_handler_end_tape:
+
+#endif
+
 	// Acknowledge CIA interrupt and return
 	jmp clear_cia1_interrupt_flag_and_return_from_interrupt
-

c64/kernal/tape/tape_common.s

@@ -84,6 +84,14 @@ tape_ask_play:
 
 	sei                                // timing is critical for tape loading
 
+	// First check whether the button is already pressed
+
+	lda CPU_R6510
+	and #$10
+	beq tape_wait_play_done
+
+	// Turn off the motor, display message
+
 	jsr tape_motor_off
 
 	ldx #__MSG_KERNAL_PRESS_PLAY
@@ -110,6 +118,8 @@ tape_wait_play_loop:
 	and #$10                           // check for pressed button
 	bne tape_wait_play_loop
 
+tape_wait_play_done:
+
 	jsr print_return
 	jmp tape_screen_hide_motor_on