initial concept of ROM versioning, still needs quite some work

c64/kernal/assets/kernal_messages.s

@@ -17,6 +17,9 @@
 .label __MSG_KERNAL_NTSC          = __kernal_message_ntsc          - __kernal_messages_start
 #endif
 
+.label __MSG_KERNAL_PANIC         = __kernal_message_panic         - __kernal_messages_start
+.label __MSG_KERNAL_PANIC_VERSION = __kernal_message_panic_version - __kernal_messages_start
+
 
 __kernal_messages_start:
 
@@ -51,11 +54,19 @@ __kernal_message_to_hex:
 #if CONFIG_BANNER_PAL_NTSC
 
 __kernal_message_pal:
-	.text "PAL,"
+	.text ", PAL"
 	.byte $80 + $20 // end of string mark + space
 
 __kernal_message_ntsc:
-	.text "NTSC,"
+	.text ", NTSC"
 	.byte $80 + $20 // end of string mark + space
 
 #endif // CONFIG_BANNER_PAL_NTSC
+
+__kernal_message_panic:
+	.text "KERNAL PANI"
+	.byte $80 + $43 // end of string mark + 'C'
+
+__kernal_message_panic_version:
+	.text " - ROM MISMATC"
+	.byte $80 + $48 // end of string mark + 'H'

c64/kernal/panic.s

@@ -0,0 +1,61 @@
+
+//
+// Something terrible happened - show the panic screen
+//
+
+// .A = 0 - just panic, no extra message
+// .A = 1 - ROM version mismatch
+
+panic:
+
+	sei
+	pha
+
+	jsr IOINIT
+	jsr setup_vicii
+	jsr clear_screen
+
+	// XXX disable NMIs
+
+	ldx #$14
+	ldy #$0E
+	jsr plot_set
+
+	ldx #__MSG_KERNAL_PANIC
+	jsr print_kernal_message
+
+	pla
+	beq kernal_panic_infinite_loop
+	pha
+
+	ldx #$02
+	ldy #$02
+	jsr plot_set
+
+	pla
+	pha
+	jsr print_hex_byte
+
+	pla
+	cmp #$01
+	bne kernal_panic_infinite_loop
+
+	ldx #__MSG_KERNAL_PANIC_VERSION
+	jsr print_kernal_message
+
+kernal_panic_infinite_loop:
+	ldx #$00
+	stx VIC_EXTCOL
+
+	ldx #$80
+!:
+	dex
+	bne !-
+
+	ldx #$06
+	stx VIC_EXTCOL
+!:
+	dex
+	bne !-
+
+	beq kernal_panic_infinite_loop // branch always

c64/kernal/xxxx.rom_revision_kernal.s

@@ -0,0 +1,34 @@
+
+//
+// !!! PROPOSAL ONLY !!! PROPOSAL ONLY !!! NOT FOR USING EXTERNALLY YET !!!
+//
+//
+// Do not change! Locations of the following data should be constant - now and forever!
+//
+// If you want to integrate Open ROMs support in your emulator, FPGA ccomputer, etc. - this
+// is the official way to recognize the ROM and it's revision.
+//
+
+
+// XXX we need to find a safe address within $E4D3-$FFFF range, we need 20 bytes
+
+
+panic_vector: 
+
+	// This vector is to be used by non-Kernal ROMs, if they want to complain
+	// about incompatible ROM releases - jump via this vector with .A set to 1
+
+	.byte <panic
+	.byte >panic
+
+rom_revision_kernal:
+
+	.text "OR"               // Magic string, after "Open ROMs"
+	.byte CONFIG_ID          // Config file ID, might change between revisions
+
+rom_revision_kernal_string:
+
+	.text "DEVEL SNAPSHOT"   // Actual ROM revision string
+	.byte $00
+
+__rom_revision_kernal_end: