update reset routine based on c64 prg pp263-269

c64/kernal/cartridge_check.s

@@ -0,0 +1,13 @@
+; c64 prg p263
+
+cartridge_check:
+	ldx #$04
+cartridge_check_l1:
+	lda $8002,x
+	cmp cartridge_signature,x
+	bne no_cartridge
+	dex
+	bpl cartridge_check_l1
+	jmp ($8000)
+cartridge_signature:
+	.byte $C3,$C2,$CD,$38,$30

c64/kernal/reset_entry.s

@@ -5,20 +5,26 @@
 reset_entry:
 	; The GPL program at https://github.com/Klaus2m5/6502_65C02_functional_tests/blob/master/6502_functional_test.a65
 	; uses the following initial reset sequence
+	; affirmed by c64 PRG p269
 	cld
 	ldx #$ff
 	txs
 	sei
 
+	; C64 PRG p269
+	jsr cartridge_check
 
 	; The following routine is based on reading the public KERNAL jumptable routine
 	; list, and making unimaginative assumptions about what should be done on reset.
-	; Initialising IO is obviously required. 
+	; Initialising IO is obviously required.  also indicated by c64 prg p269.
 	jsr ioinit
-	; Setting up the screen is obviously required
+	; Setting up the screen and testing ram is obviously required
+	; also affirmed by p269 of c64 prg
 	jsr ramtas
 	; Resetting IO vectors is obviously required, if we want interrupts to run
+	; also affirmed by c64 prg p269
 	jsr restor
 
 	; What do we do when finished?  A C64 jumps into the BASIC ROM
+	; c64 prg p269
 	jmp ($a000)