diff --git a/c64/aliases/,aliases_ram_lowmem.s b/c64/aliases/,aliases_ram_lowmem.s
index 0c63eaa0..4dfdefcd 100644
--- a/c64/aliases/,aliases_ram_lowmem.s
+++ b/c64/aliases/,aliases_ram_lowmem.s
@@ -193,12 +193,12 @@
 	// [!] XXX document $2A7-$2FF usage
 
 	// BASIC vectors
-	.label IERROR    = $300  // $300-$301  -- NOT IMPLEMENTED --
-	.label IMAIN     = $302  // $302-$303  -- NOT IMPLEMENTED --
-	.label ICRNCH    = $304  // $304-$305  -- NOT IMPLEMENTED --
-	.label IQPLOP    = $306  // $306-$307  -- NOT IMPLEMENTED --
-	.label IGONE     = $308  // $308-$309  -- NOT IMPLEMENTED --
-	.label IEVAL     = $30A  // $30A-$30B  -- NOT IMPLEMENTED --
+	.label IERROR    = $300  // $300-$301
+	.label IMAIN     = $302  // $302-$303
+	.label ICRNCH    = $304  // $304-$305
+	.label IQPLOP    = $306  // $306-$307
+	.label IGONE     = $308  // $308-$309
+	.label IEVAL     = $30A  // $30A-$30B
 	
 	.label SAREG     = $30C  //            .A storage, for SYS call
 	.label SXREG     = $30D  //            .X storage, for SYS call
diff --git a/c64/basic/basic_cold_start.s b/c64/basic/basic_cold_start.s
index 2107d6ca..38d9cefb 100644
--- a/c64/basic/basic_cold_start.s
+++ b/c64/basic/basic_cold_start.s
@@ -1,7 +1,15 @@
 // BASIC Cold start entry point
 // Compute's Mapping the 64 p211
 
-basic_cold_start:	
+basic_cold_start:
+
+	// Setup vectors at $300
+	ldy #$0B
+!:
+	lda basic_vector_defaults, y
+	sta IERROR, y
+	dey
+	bpl !-
 
 	// Print startup banner
 	jsr printf // XXX don't use printf, keep it for debug purposes only
diff --git a/c64/basic/basic_vector_defaults.s b/c64/basic/basic_vector_defaults.s
new file mode 100644
index 00000000..5f2f5943
--- /dev/null
+++ b/c64/basic/basic_vector_defaults.s
@@ -0,0 +1,16 @@
+
+//
+// Default values for BASIC vectors - described in:
+//
+// - [RG64] C64 Programmer's Reference Guide   - pages 68-70
+// - [CM64] Compute's Mapping the Commodore 64 - page 318
+//
+
+basic_vector_defaults:
+
+	.word ERROR     // IERROR
+	.word MAIN      // IMAIN
+	.word CHRNCH    // ICHRNCH
+	.word QPLOP     // IQPLOP
+	.word GONE      // IGONE
+	.word EVAL      // IEVAL
diff --git a/c64/basic/cmd_unimplemented.s b/c64/basic/cmd_unimplemented.s
index 67ec4811..ffdffd96 100644
--- a/c64/basic/cmd_unimplemented.s
+++ b/c64/basic/cmd_unimplemented.s
@@ -1,82 +1,156 @@
+//
 // Default handler for all not-yet-implemented commands
+//
+// Note: NOPs are here just to make debugging easier!
+//
 
 cmd_for:
+	nop
 cmd_next:
+	nop
 cmd_data:
+	nop
 cmd_inputhash:
+	nop
 cmd_input:
+	nop
 cmd_dim:
+	nop
 cmd_read:
+	nop
 cmd_let:
+	nop
 cmd_if:
+	nop
 cmd_restore:
+	nop
 cmd_gosub:
+	nop
 cmd_return:
+	nop
 	
 	// $90-$9F
+
 cmd_on:
+	nop
 cmd_wait:
+	nop
 cmd_save:
+	nop
 cmd_verify:
+	nop
 cmd_def:
+	nop
 cmd_poke:
+	nop
 cmd_printhash:
+	nop
 cmd_print:
+	nop
 cmd_cont:
+	nop
 cmd_cmd:
+	nop
 cmd_open:
-	
+	nop
+
 	// $A0-$AF
+
 cmd_close:
+	nop
 cmd_get:
+	nop
 cmd_tab:
+	nop
 cmd_to:
+	nop
 cmd_fn:
+	nop
 cmd_spc:
+	nop
 cmd_then:
+	nop
 cmd_not:
+	nop
 cmd_step:
+	nop
 cmd_plus:
+	nop
 cmd_minus:
+	nop
 cmd_mult:
+	nop
 cmd_div:
+	nop
 cmd_exponent:
+	nop
 cmd_and:
-	
+	nop
+
 	// $B0-$BF
+
 cmd_or:
+	nop
 cmd_greater:
+	nop
 cmd_equal:
+	nop
 cmd_less:
+	nop
 cmd_sgn:
+	nop
 cmd_int:
+	nop
 cmd_abs:
+	nop
 cmd_usr:
+	nop
 cmd_fre:
+	nop
 cmd_pos:
+	nop
 cmd_sqr:
+	nop
 cmd_rnd:
+	nop
 cmd_log:
+	nop
 cmd_exp:
+	nop
 cmd_cos:
+	nop
 cmd_sin:
-	
+	nop
+
 	// $C0-$CF
+
 cmd_tan:
+	nop
 cmd_atn:
+	nop
 cmd_peek:
+	nop
 cmd_len:
+	nop
 cmd_str:
+	nop
 cmd_val:
+	nop
 cmd_asc:
+	nop
 cmd_chr:
+	nop
 cmd_left:
+	nop
 cmd_right:
+	nop
 cmd_mid:
+	nop
 cmd_go:
- 	
+ 	nop
+
 	// Undefined tokens
+
 cmd_unimplemented:
 
-
 	jmp do_NOT_IMPLEMENTED_error