more work towards Mega65 native mode, added NSYS command

src/basic/assets/packed_keywords_03.s

@@ -0,0 +1,12 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# M65 BASIC_1 #TAKE
+// #LAYOUT# X16 BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+#if ROM_LAYOUT_M65
+
+packed_freq_keywords_03:
+
+	put_packed_freq_keywords_03()
+
+#endif

src/basic/basic_commands/cmd_sys.s

@@ -3,15 +3,39 @@
 // #LAYOUT# *   *       #IGNORE
 
 
+#if ROM_LAYOUT_M65
+
+cmd_nsys:
+	
+	// NSYS requires an argument
+
+	jsr is_end_of_statement
+	bcs_16 do_SYNTAX_error
+	bra cmd_sys_nsys_common
+
+#endif
+
 cmd_sys:
 	
-	jsr is_end_of_statement
-	bcc !+
-
 	// SYS requires an argument
-	jmp do_SYNTAX_error
-	
-!:
+
+	jsr is_end_of_statement
+	bcs_16 do_SYNTAX_error
+
+#if ROM_LAYOUT_M65
+
+	// Make sure we are in C64 compatibility mode
+
+	jsr M65_ISMODE65
+	bne cmd_sys_nsys_common
+	jsr M65_MODE64
+
+	// FALLTROUGH
+
+cmd_sys_nsys_common:
+
+#endif
+
 	//
 	// XXX Temporary ugly hack to support 'SYS PI*656'
 	//

src/basic/basic_commands_03_m65/cmd__jumptable_03.s

@@ -0,0 +1,17 @@
+// #LAYOUT# M65 BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Jumptable for BASIC commands with tokens prefixed by $03
+//
+
+.const command_03_list = List().add(
+
+	cmd_nsys
+)
+
+
+command_03_jumptable:
+
+	// Note: 65C02 has the page boundary vector bug fixed!
+	put_jumptable(command_03_list)

src/basic/basic_commands_03_m65/cmd_nsys.s

@@ -0,0 +1,7 @@
+// #LAYOUT# M65 BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+
+// PLACEHOLDER for completeness - jumptable contains direct address
+
+// NSYS command is implemented together with SYS

src/basic/engine_editor/tokenise_line.s

@@ -98,6 +98,18 @@ tokenise_line_loop:
 	jsr tk_search
 	bcc tokenise_line_keyword_02                 // branch if keyword identified
 
+#endif
+
+#if ROM_LAYOUT_M65
+
+	lda #<packed_freq_keywords_03
+	sta FRESPC+0
+	lda #>packed_freq_keywords_03
+	sta FRESPC+1
+
+	jsr tk_search
+	bcc tokenise_line_keyword_03                 // branch if keyword identified
+
 #endif
 
 	// Shorten packed keyword candidate and try again
@@ -173,6 +185,19 @@ tokenise_line_char:
 
 // Support for extended keyword lists
 
+#if ROM_LAYOUT_M65
+
+tokenise_line_keyword_03:
+
+	// Store the token list index
+
+	lda #$03
+	skip_2_bytes_trash_nvz
+
+	// FALLTROUGH
+
+#endif
+
 #if !HAS_SMALL_BASIC
 
 tokenise_line_keyword_02:

src/basic/engine_runtime/execute_line_statements.s

@@ -46,7 +46,11 @@ execute_statements:
 
 #else
 
+#if ROM_LAYOUT_M65
+	cpx #$04
+#else
 	cpx #$03
+#endif
 	bcc execute_statements_extended
 
 #endif
@@ -93,6 +97,13 @@ execute_statements_extended:
 	cpx #$02
 	beq execute_statements_02
 
+#if ROM_LAYOUT_M65
+
+	cpx #$03
+	beq execute_statements_03
+
+#endif
+
 	jmp do_SYNTAX_error
 
 #endif
@@ -171,6 +182,27 @@ execute_statements_02:
 
 #endif // !HAS_SMALL_BASIC
 
+#if ROM_LAYOUT_M65
+
+execute_statements_03:
+
+	// Get the sub-token, check that it is valid
+
+	jsr fetch_character
+	cmp #$00
+	beq_16 do_SYNTAX_error
+
+	cmp #(TK__MAXTOKEN_keywords_03+1)
+	bcs_16 do_SYNTAX_error
+
+	// Use jumptable to go to the command routine
+
+	asl
+	tax
+	jmp (command_03_jumptable - 2, x)
+
+#endif // ROM_LAYOUT_M65
+
 execute_statements_end_of_line:
 
 	// First check, if we are in direct mode - if so,

src/basic/print/list_single_line.s

@@ -94,6 +94,10 @@ list_not_quote:
 	cmp #$02
 	beq list_display_token_02
 #endif
+#if ROM_LAYOUT_M65
+	cmp #$03
+	beq list_display_token_03
+#endif
 
 	// Check for literals
 	cmp #$7F
@@ -228,6 +232,24 @@ list_display_token_02:
 
 #endif
 
+#if ROM_LAYOUT_M65
+
+list_display_token_03:
+
+	// Display a 2-byte token - for extended BASIC
+	jsr list_fetch_subtoken
+
+	// Check if token is known
+	cpx #TK__MAXTOKEN_keywords_03
+	bcs list_is_unknown
+
+	// Now ask for it to be printed
+	phy_trash_a
+	jsr print_packed_keyword_03
+	jmp_8 list_display_token_ext_done
+
+#endif
+
 list_fetch_subtoken:
 
 	// Fetch the sub-token

src/basic/print/print_packed_freq_string.s

@@ -55,6 +55,16 @@ print_packed_keyword_02:               // .X - token number
 
 #endif
 
+#if ROM_LAYOUT_M65
+
+print_packed_keyword_03:               // .X - token number
+
+	lda #<packed_freq_keywords_03
+	ldy #>packed_freq_keywords_03
+	bne print_freq_packed_string       // branch always
+
+#endif
+
 print_packed_keyword_V2:               // .X - token number
 
 	lda #<packed_freq_keywords_V2