slightly more precise pulse measurement

c64/kernal/tape/load_tape_normal.s

@@ -49,7 +49,7 @@ load_tape_normal:
 	// Let timer A run continuously
 
 	ldx #%00010001                     // start timer, force latch reload
-	stx CIA2_CRA  // $DD0E
+	stx CIA2_CRA    // $DD0E
 	
 	// Start playing
 	jsr tape_ask_play

c64/kernal/tape/tape_normal_get_byte.s

@@ -20,7 +20,7 @@ tape_normal_get_byte:
 	// First we need a byte marker - (L,M)
 !:
 	jsr tape_normal_get_pulse
-	cmp #($100 - $95 - $05)
+	cmp #($100 - $95 - $04)
 	bcs !-                             // too short for a long pulse
 	jsr tape_normal_get_pulse
 	bcs !-                             // too short for a medium pulse

c64/kernal/tape/tape_normal_get_pulse.s

@@ -32,11 +32,12 @@ tape_normal_get_pulse:
 	// lda - 4 cycles
 	// ldx - 2 cycles
 	// stx - 4 cycles
-	// plus approx. 3 cycles (bit + beq time divided by 2) from value change to 'bit' instruction,
-	// this is total 19 cycles, or $5 periods of 4 ticks (timer A) each - we need to take it into account
+	// plus average 3 cycles (bit + beq time divided by 2) from value change to 'bit' instruction
+	// minus average 2 cycles due to timer A running continouslyy (might start before the pulse)
+	// this is total 17 cycles, or $4 periods of 4 ticks (timer A) each - we need to take it into account
 	// every time we check the pulse length
 
-	cmp #($100 - $6C - $05)            // short vs medium is the default check
+	cmp #($100 - $6C - $04)            // short vs medium is the default check
 	rts