diff --git a/src/aliases/,aliases_ram_lowmem_m65.s b/src/aliases/,aliases_ram_lowmem_m65.s
index b4ebafdc..4a65c6b4 100644
--- a/src/aliases/,aliases_ram_lowmem_m65.s
+++ b/src/aliases/,aliases_ram_lowmem_m65.s
@@ -39,16 +39,17 @@
 
 	.label M65_SCRSEG       = $580 // $580-$581  segment address (2 higher bytes) of the screen memory
 	.label M65_SCRBASE      = $582 // $582-$583  first byte of screen memory
-	.label M65_SCRGUARD     = $584 // $584-$585  last byte of screen memory + 1
-	.label M65_COLVIEW      = $586 // $586-$587  first byte of color memory viewport
-	.label M65_COLVIEWMAX   = $588 // $588-$589  largest allowed value of M65_SCRVIEW
-	.label M65_SCRMODE      = $58A //            0 = 40x25, 1 = 80x25, 2 = 80x50 
-	.label M64_SCRWINMODE   = $58B //            $00 = normal mode, $FF = window enabled
-	.label M65_TXTWIN_X0    = $58C //            text window - top-left X coordinate, starting from 0
-	.label M65_TXTWIN_Y0    = $58D //            text window - top-left Y coordinate, starting from 0
-	.label M65_TXTWIN_X1    = $58E //            text window - bottom-right X coordinate + 1
-	.label M65_TXTWIN_Y1    = $58F //            text window - bottom-right Y coordinate + 1
-	.label M65_TXTROW_OFF   = $590 // $590-$591  offset to the current text row
-	                               // $592-$5FF  -- UNUSED --
+	.label M65_SCRGUARD     = $584 // $584-$585  last byte of screen memory + 1  XXX is it needed?
+	.label M65_COLGUARD     = $586 // $586-$587  last byte of colour memory + 1
+	.label M65_COLVIEW      = $588 // $588-$589  first byte of color memory viewport
+	.label M65_COLVIEWMAX   = $58A // $58A-$58B  largest allowed value of M65_COLVIEW
+	.label M65_SCRMODE      = $58C //            0 = 40x25, 1 = 80x25, 2 = 80x50 
+	.label M64_SCRWINMODE   = $58D //            $00 = normal mode, $FF = window enabled
+	.label M65_TXTWIN_X0    = $58E //            text window - top-left X coordinate, starting from 0
+	.label M65_TXTWIN_Y0    = $58F //            text window - top-left Y coordinate, starting from 0
+	.label M65_TXTWIN_X1    = $590 //            text window - bottom-right X coordinate + 1
+	.label M65_TXTWIN_Y1    = $591 //            text window - bottom-right Y coordinate + 1
+	.label M65_TXTROW_OFF   = $592 // $592-$593  offset to the current text row
+	                               // $594-$5FF  -- UNUSED --
 	.label M65_RS232_INBUF  = $600 // $600-$6FF  -- reserved for RS-232 input buffer --
 	.label M65_RS232_OUTBUF = $700 // $700-$7FF  -- reserved for RS-232 output buffer --
diff --git a/src/kernal/extapi_m65/mega65_mode65.s b/src/kernal/extapi_m65/mega65_mode65.s
index dc6c8207..273f98ee 100644
--- a/src/kernal/extapi_m65/mega65_mode65.s
+++ b/src/kernal/extapi_m65/mega65_mode65.s
@@ -43,7 +43,7 @@ M65_MODE65:
 
 	// Set screen mode to 80x25
 
-	lda #$01
+	lda #$02
 	jsr m65_scrmodeset_internal
 
 	// Clear the screen
diff --git a/src/kernal/screen_m65/mega65_clear_attributes.s b/src/kernal/screen_m65/mega65_clear_attributes.s
new file mode 100644
index 00000000..7c5dc476
--- /dev/null
+++ b/src/kernal/screen_m65/mega65_clear_attributes.s
@@ -0,0 +1,11 @@
+// #LAYOUT# M65 KERNAL_1 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+m65_clear_attributes:
+
+	lda COLOR
+	and #$0F
+	sta COLOR
+
+	rts
diff --git a/src/kernal/screen_m65/mega65_clrscr.s b/src/kernal/screen_m65/mega65_clrscr.s
index f2dcfb1c..ff143655 100644
--- a/src/kernal/screen_m65/mega65_clrscr.s
+++ b/src/kernal/screen_m65/mega65_clrscr.s
@@ -2,15 +2,12 @@
 // #LAYOUT# *   *        #IGNORE
 
 
-// XXX deduplicate pointer manipulation
 
 M65_CLRSCR:
 
 	// Clear additional attributes from the color code
 
-	lda COLOR
-	and #$0F
-	sta COLOR
+	jsr m65_clear_attributes
 
 	// Disable the window mode
 
@@ -19,32 +16,19 @@ M65_CLRSCR:
 
 	// FALLTROUGH
 
-m65_clrscr_takeover:
+m65_clrscr_takeover: // .A has to be 0
 
-	// Set the viewport to the beginning of screen memory - variables:
+	// Set the viewport to the beginning of screen memory - variable:
 	// - M65_COLVIEW
-	// To clear the screen, two zeropage long pointers will be used, initialize them too
-	// - M65_LPNT_SCR  for screen memory
-	// - M65_LPNT_KERN for colour memory (starts from $FF80000) // XXX preserve this on stack, restore afterwards
+	// It will serve as line counter
 
 	sta M65_COLVIEW+0
 	sta M65_COLVIEW+1
 
-	sta M65_LPNT_KERN+0
-	sta M65_LPNT_KERN+1
-	lda #$F8
-	sta M65_LPNT_KERN+2
-	lda #$0F
-	sta M65_LPNT_KERN+3
+	// Clear the row offset, so that it won't interfere
 
-	lda M65_SCRBASE+0
-	sta M65_LPNT_SCR+0	
-	lda M65_SCRBASE+1
-	sta M65_LPNT_SCR+1
-	lda M65_SCRSEG+0
-	sta M65_LPNT_SCR+2
-	lda M65_SCRSEG+1
-	sta M65_LPNT_SCR+3
+	sta M65_TXTROW_OFF+0
+	sta M65_TXTROW_OFF+1
 
 	// Clear the whole screen+color memory
 
@@ -54,45 +38,56 @@ m65_clrscr_takeover:
 
 m65_clrscr_loop:
 
-	// Clear 80 characters
+	// Prepare M65_LPNT_SCR, let it point to color memory
+
+	jsr m65_helper_scrlpnt_color
+
+	// Clear color for the whole line
 
 	ldz #$4F                                     // 80 bytes
-!:
-	lda #$20
-	sta_lp (M65_LPNT_SCR),z
 	lda COLOR
-	sta_lp (M65_LPNT_KERN),z
+!:
+	sta_lp (M65_LPNT_SCR),z
 
 	dez
 	bpl !-
 
-	// Move M65_LPNT_SCR and M65_LPNT_KERN 80 characters forward
-	// XXX deduplicate with window clearing
+	// Let M65_LPNT_SCR point to scren memory
 
-	clc
-	lda M65_LPNT_SCR+0
-	adc #$50
-	sta M65_LPNT_SCR+0
-	bcc !+
-	inc M65_LPNT_SCR+1
-!:
-	clc
-	lda M65_LPNT_KERN+0
-	adc #$50
-	sta M65_LPNT_KERN+0
-	bcc !+
-	inc M65_LPNT_KERN+1
-!:
-	// Check if we have more rows to clear
+	jsr m65_helper_scrlpnt_to_screen
 
-	lda M65_LPNT_SCR+1
-	cmp M65_SCRGUARD+1
+	// Clear characters in the whole line
+
+	ldz #$4F                                     // 80 bytes
+	lda #$20
+!:
+	sta_lp (M65_LPNT_SCR),z
+
+	dez
+	bpl !-
+
+	// Advance by one line, do next iteration
+
+	// XXX this can probably be deduplicated
+	clc
+	lda M65_COLVIEW+0
+	adc #$50
+	sta M65_COLVIEW+0
+	bcc !+
+	inc M65_COLVIEW+1
+!:
+	// Check if we are allowed to progress further
+
+	lda M65_COLVIEW+1
+	cmp M65_COLVIEWMAX+1
 	bne m65_clrscr_loop
-	lda M65_LPNT_SCR+0
-	cmp M65_SCRGUARD+0
+	lda M65_COLVIEW+0
+	cmp M65_COLVIEWMAX+0
 	bne m65_clrscr_loop
 
-	// Restore .Z register
+m65_clrscr_loop_done:
+
+	// Nothing more to clear - restore .Z register
 
 	plz
 
@@ -102,6 +97,8 @@ m65_clrscr_loop:
 	lda #$00
 	sta VIC_COLPTR+0
 	sta VIC_COLPTR+1
+	sta M65_COLVIEW+0
+	sta M65_COLVIEW+1
 
 	lda M65_SCRBASE+0
 	sta VIC_SCRNPTR+0
@@ -110,7 +107,13 @@ m65_clrscr_loop:
 
     // Set screen variables
 
-	// XXX provide proper implementation, together with HOME
+	// XXX provide proper implementation
+
+    // FALLTROUGH
+
+M65_HOME:
+
+	// XXX provide proper implementation
 
 	lda #$00
 	sta M65__TXTROW
diff --git a/src/kernal/screen_m65/mega65_clrwin.s b/src/kernal/screen_m65/mega65_clrwin.s
index d57d9d1d..11e73155 100644
--- a/src/kernal/screen_m65/mega65_clrwin.s
+++ b/src/kernal/screen_m65/mega65_clrwin.s
@@ -2,16 +2,13 @@
 // #LAYOUT# *   *        #IGNORE
 
 
-// XXX deduplicate pointer manipulation
+// XXX deduplicate pointer manipulation, see M65_CLRSCR
 
 M65_CLRWIN:
 
 	// Clear additional attributes from the color code
-	// XXX deduplicate with M65_CLRSCR
 
-	lda COLOR
-	and #$0F
-	sta COLOR
+	jsr m65_clear_attributes
 
 	// Check if windowed mode; if not, go to M65_CLRSCR
 
diff --git a/src/kernal/screen_m65/mega65_screen_helpers.s b/src/kernal/screen_m65/mega65_screen_helpers.s
index d5c61caa..91247a55 100644
--- a/src/kernal/screen_m65/mega65_screen_helpers.s
+++ b/src/kernal/screen_m65/mega65_screen_helpers.s
@@ -2,7 +2,6 @@
 // #LAYOUT# *   *        #IGNORE
 
 
-
 m65_helper_scrlpnt_color:
 
 	// Set .Z to the current column
@@ -36,7 +35,7 @@ m65_helper_scrlpnt_color:
 
 m65_helper_scrlpnt_to_screen:
 
-	// Change M65_LPNT_SCR to point to screen memory (when it points to scren memory)
+	// Change M65_LPNT_SCR to point to screen memory (when it points to color memory)
 
 	lda M65_SCRSEG+1
 	sta M65_LPNT_SCR+3
diff --git a/src/kernal/screen_m65/mega65_screen_tables_misc.s b/src/kernal/screen_m65/mega65_screen_tables_misc.s
index 329d5c7a..c4a786e7 100644
--- a/src/kernal/screen_m65/mega65_screen_tables_misc.s
+++ b/src/kernal/screen_m65/mega65_screen_tables_misc.s
@@ -6,19 +6,19 @@ m65_scrtab_vic_ctrlb:        // parameters for VIC control register B
 
 	.byte %00100000 // 40x25 + extended attributes
 	.byte %10100000 // 80x25 + extended attributes
-	.byte %10100100 // 80x50 + extended attributes
+	.byte %10101000 // 80x50 + extended attributes
 
 m65_scrtab_colviewmax_lo:       // maximum allowed color viewport start - low byte
 
-	.byte $10
-	.byte $10
-	.byte $40
+	.byte <((128-25)*80)
+	.byte <((128-25)*80)
+	.byte <((128-50)*80)
 
 m65_scrtab_colviewmax_hi:       // maximum allowed color viewport start - high byte
 
-	.byte $27
-	.byte $27
-	.byte $1F
+	.byte >((128-25)*80)
+	.byte >((128-25)*80)
+	.byte >((128-50)*80)
 
 m65_scrtab_scrolx:           // values for VIC_SCROLX
 
diff --git a/src/kernal/screen_m65/mega65_scrmodeset.s b/src/kernal/screen_m65/mega65_scrmodeset.s
index 00ecf9a4..0cbe613d 100644
--- a/src/kernal/screen_m65/mega65_scrmodeset.s
+++ b/src/kernal/screen_m65/mega65_scrmodeset.s
@@ -70,15 +70,15 @@ m65_scrmodeset_internal: // entry point for M65_MODE65
 	stx VIC_SCRNPTR+2
 
 	// Set the following locations:
-	// - M65_SCRBASE                   - for screen starting from $xxxx6000
+	// - M65_SCRBASE                   - for screen starting from $xxxx9000
 	// - VIC_SCRNPTR+0/+1              - for screen viewport start
 	// - M65_COLVIEW, VIC_COLPTR       - for using color memory from the start
 
-	ldx #$60
+	ldx #>($9000)
 	stx M65_SCRBASE+1
 	stx VIC_SCRNPTR+1
 
-	ldx #$00
+	ldx #<($9000)
 	stx M65_SCRBASE+0
 
 	stx VIC_SCRNPTR+0
@@ -89,14 +89,19 @@ m65_scrmodeset_internal: // entry point for M65_MODE65
 	stx VIC_COLPTR+1
 
 	// Set the following locations:
-	// - M65_SCREND                    - for max 200 lines of virtual screen
+	// - M65_SCRGUARD, M65_COLGUARD    - for max 128 lines of virtual screen
 	// - M65_COLVIEWMAX                - as above, but depending on the mode
 
-	ldx #$80
+	ldx #<($9000 + 80 * 128)
 	stx M65_SCRGUARD+0
-	ldx #$9E
+	ldx #>($9000 + 80 * 128)
 	stx M65_SCRGUARD+1
 
+	ldx #<(80 * 128)
+	stx M65_COLGUARD+0
+	ldx #>(80 * 128)
+	stx M65_COLGUARD+1
+
 	ldx M65_SCRMODE
 	lda m65_scrtab_colviewmax_lo, x
 	sta M65_COLVIEWMAX+0