diff --git a/Makefile b/Makefile
index 49f6bd6e..71466c12 100644
--- a/Makefile
+++ b/Makefile
@@ -398,11 +398,14 @@ test_generic_x128: build/kernal_generic.rom build/basic_generic.rom build/symbol
 test_testing: build/kernal_testing.rom build/basic_testing.rom build/symbols_testing.vs
 	x64 -kernal build/kernal_testing.rom -basic build/basic_testing.rom -moncommands build/symbols_testing.vs -1 $(TESTTAPE) -8 $(TESTDISK)
 
+test_ultimate64: build/kernal_ultimate64.rom build/basic_ultimate64.rom build/symbols_ultimate64.vs
+	x64 -kernal build/kernal_ultimate64.rom -basic build/basic_ultimate64.rom -moncommands build/symbols_ultimate64.vs -1 $(TESTTAPE) -8 $(TESTDISK)
+
 test_mega65: $(TARGET_M65_x)
 	../xemu/build/bin/xmega65.native -dmarev 2 -forcerom -loadrom $(TARGET_M65_x)
 
-test_ultimate64: build/kernal_ultimate64.rom build/basic_ultimate64.rom build/symbols_ultimate64.vs
-	x64 -kernal build/kernal_ultimate64.rom -basic build/basic_ultimate64.rom -moncommands build/symbols_ultimate64.vs -1 $(TESTTAPE) -8 $(TESTDISK)
+test_cx16: $(TARGET_X16_x)
+	../x16-emulator/x16emu -rom $(TARGET_X16_x)
 
 test_hybrid: build/kernal_hybrid.rom build/symbols_hybrid.vs
 	@echo
diff --git a/c64/aliases/,aliases_hardware_cx16.s b/c64/aliases/,aliases_hardware_cx16.s
new file mode 100644
index 00000000..79bfbb4a
--- /dev/null
+++ b/c64/aliases/,aliases_hardware_cx16.s
@@ -0,0 +1,73 @@
+
+//
+// Names of hardware registers
+//
+
+
+#if CONFIG_PLATFORM_COMMANDER_X16
+
+	// VERA registers
+
+	.label __VERA_BASE   = $9F20  // base address of the chip
+
+	.label VERA_ADDR_LO  = $9F20
+	.label VERA_ADDR_MID = $9F21
+	.label VERA_ADDR_HI  = $9F22
+
+	.label VERA_DATA0    = $9F23
+	.label VERA_DATA1    = $9F24
+
+	.label VERA_CTRL     = $9F25
+
+	.label VERA_IEN      = $9F26
+	.label VERA_ISR      = $9F27
+
+	// VIA #1 registers
+
+	.label __VIA1_BASE  = $9F60  // base address of the chip
+
+	.label VIA1_PRB     = $9F60
+	.label VIA1_PRA     = $9F61
+	.label VIA1_DDRB    = $9F62
+	.label VIA1_DDRA    = $9F63
+
+	.label VIA1_T1C_L   = $9F64
+	.label VIA1_T1C_H   = $9F65
+	.label VIA1_T1L_L   = $9F66
+	.label VIA1_T1L_H   = $9F67
+	.label VIA1_T2C_L   = $9F68
+	.label VIA1_T2C_H   = $9F69
+
+	.label VIA1_SR      = $9F6A
+	.label VIA1_ACR     = $9F6B
+	.label VIA1_PCR     = $9F6C
+	.label VIA1_IFR     = $9F6D
+	.label VIA1_IER     = $9F6E
+
+	.label VIA1_PRA_NH  = $9F6F
+
+	// VIA #2 registers
+
+	.label __VIA2_BASE  = $9F70  // base address of the chip
+
+	.label VIA2_PRB     = $9F70
+	.label VIA2_PRA     = $9F71
+	.label VIA2_DDRB    = $9F72
+	.label VIA2_DDRA    = $9F73
+
+	.label VIA2_T1C_L   = $9F74
+	.label VIA2_T1C_H   = $9F75
+	.label VIA2_T1L_L   = $9F76
+	.label VIA2_T1L_H   = $9F77
+	.label VIA2_T2C_L   = $9F78
+	.label VIA2_T2C_H   = $9F79
+
+	.label VIA2_SR      = $9F7A
+	.label VIA2_ACR     = $9F7B
+	.label VIA2_PCR     = $9F7C
+	.label VIA2_IFR     = $9F7D
+	.label VIA2_IER     = $9F7E
+
+	.label VIA2_PRA_NH  = $9F7F
+
+#endif
diff --git a/c64/aliases/,aliases_rom_cart.s b/c64/aliases/,aliases_rom_cart.s
index 50decc3f..620960a7 100644
--- a/c64/aliases/,aliases_rom_cart.s
+++ b/c64/aliases/,aliases_rom_cart.s
@@ -1,5 +1,10 @@
 
+#if CONFIG_PLATFORM_COMMODORE_64
+
 	// Cartridge ROM locations
+
 	.label ICART_COLD_START  = $8000  // $8000-$8001, cartridge cold start vector
 	.label ICART_WARM_START  = $8002  // $8002-$8003, cartridge warm start vector (RESTORE key)
 	.label CART_SIG          = $8004  // $8004-$8008, signature for cartridge detection
+
+#endif
diff --git a/c64/basic/init/e394.basic_cold_start.s b/c64/basic/init/e394.basic_cold_start.s
index 670cdda6..a7ba4138 100644
--- a/c64/basic/init/e394.basic_cold_start.s
+++ b/c64/basic/init/e394.basic_cold_start.s
@@ -8,7 +8,7 @@
 
 basic_cold_start:
 
-#if !ROM_LAYOUT_M65                    // can be safely skipped in Mega65 ROM layout
+#if ROM_LAYOUT_STD // skip on non-sgtandard ROM layouts - they produce single image nevertheless
 
 	// Before doing anything, check if we have a compatible BASIC/KERNAL pair
 
diff --git a/c64/kernal/assets/cartridge_signature.s b/c64/kernal/assets/cartridge_signature.s
index a0fdcc4b..92a3b776 100644
--- a/c64/kernal/assets/cartridge_signature.s
+++ b/c64/kernal/assets/cartridge_signature.s
@@ -1,4 +1,5 @@
 // #LAYOUT# STD *        #TAKE
+// #LAYOUT# X16 *        #IGNORE
 // #LAYOUT# *   KERNAL_0 #TAKE
 // #LAYOUT# *   *        #IGNORE
 
diff --git a/c64/kernal/init/cartridge_check.s b/c64/kernal/init/cartridge_check.s
index b47c61e7..3686a7f8 100644
--- a/c64/kernal/init/cartridge_check.s
+++ b/c64/kernal/init/cartridge_check.s
@@ -1,4 +1,5 @@
 // #LAYOUT# STD *        #TAKE
+// #LAYOUT# X16 *        #IGNORE
 // #LAYOUT# *   KERNAL_0 #TAKE
 // #LAYOUT# *   *        #IGNORE
 
diff --git a/c64/kernal/init/fce2.hw_entry_reset.s b/c64/kernal/init/fce2.hw_entry_reset.s
index 474668f2..0d36a2d6 100644
--- a/c64/kernal/init/fce2.hw_entry_reset.s
+++ b/c64/kernal/init/fce2.hw_entry_reset.s
@@ -19,6 +19,8 @@ hw_entry_reset:
 	ldx #$FF
 	txs
 
+#if CONFIG_PLATFORM_COMMODORE_64
+
 	// The following routine is based on reading the public KERNAL jumptable routine
 	// list, and making unimaginative assumptions about what should be done on reset.
 	// Also, https://codebase64.org/doku.php?id=base:assembling_your_own_cart_rom_image was used
@@ -30,10 +32,10 @@ hw_entry_reset:
 	jmp (ICART_COLD_START)
 !:
 
-#if CONFIG_PLATFORM_COMMODORE_64
 	// Disable the screen (and set 40 columns) to prevent visual glitches later
 	ldx #$28
 	stx VIC_SCROLX
+
 #endif
 
 	// Initialising IO is obviously required. Also indicated by c64 prg p269.
diff --git a/c64/kernal/init/fd50.ramtas.s b/c64/kernal/init/fd50.ramtas.s
index 412797bc..70a4abc2 100644
--- a/c64/kernal/init/fd50.ramtas.s
+++ b/c64/kernal/init/fd50.ramtas.s
@@ -49,6 +49,8 @@ RAMTAS:
 	ldx #>$033C
 	stx TAPE1+1
 
+#if CONFIG_PLATFORM_COMMODORE_64
+
 	// Set screen address pointer ("Compute's Mapping the 64" p238)
 	// This is obvious boiler plate containing no creative input, but to avoid
 	// unnecessarily similarity to the C64 KERNAL, we use X instead of A to do this,
@@ -95,4 +97,19 @@ ramtas_32k:
 	ldy #$80
 	bne !- // branch always
 
+#elif CONFIG_PLATFORM_COMMANDER_X16
+
+	ldx #>$0800
+	stx MEMSTR+1
+
+	ldy #$9F
+	sty MEMSIZK+1
+
+#else
+
+	.error "Please fill-in RAMTAS"
+
+#endif // platform
+
+
 #endif // ROM layout
diff --git a/c64/kernal/interrupts/fe47.default_nmi_handler.s b/c64/kernal/interrupts/fe47.default_nmi_handler.s
index 96a2bccb..5e86373f 100644
--- a/c64/kernal/interrupts/fe47.default_nmi_handler.s
+++ b/c64/kernal/interrupts/fe47.default_nmi_handler.s
@@ -17,10 +17,15 @@ default_nmi_handler:
 
 	// XXX confirm NMIs from CIA, or no other NMI will arrive!
 
+#if CONFIG_PLATFORM_COMMODORE_64
+
 	jsr cartridge_check
 	bne !+
 	jmp (ICART_WARM_START)
 !:
+
+#endif
+
 	// According to C64 Wiki, if STOP key is pressed, the routine assumes warm start request
 
 	// XXX is it right? how to check that IRQ was caused by RESTORE?
diff --git a/c64/kernal/jumptable/fff3.jiobase.s b/c64/kernal/jumptable/fff3.jiobase.s
index 8f0b756b..0af3c7a1 100644
--- a/c64/kernal/jumptable/fff3.jiobase.s
+++ b/c64/kernal/jumptable/fff3.jiobase.s
@@ -16,6 +16,21 @@
 // As there is nothing between here and $FFFA, we can just hard code this in place.
 
 // iobase: - commented out to prevent label naming conflict
+
+#if CONFIG_PLATFORM_COMMODORE_64
+
     ldy #$DC
     ldx #$00
+
+#elif CONFIG_PLATFORM_COMMANDER_X16
+
+    ldy #$9F
+    ldx #$60
+
+#else
+
+	.error "Please fill-in IOBASE"
+
+#endif
+
     rts