diff --git a/presets/nes/ex1.asm b/presets/nes/ex1.asm
index 5c534140..93b82b30 100644
--- a/presets/nes/ex1.asm
+++ b/presets/nes/ex1.asm
@@ -1,3 +1,4 @@
+
 
 ;;;;; CONSTANTS
 
@@ -18,31 +19,33 @@ DMC_FREQ	equ $4010
 	org $0
 
 ScrollPos	byte	; used during NMI
+Rand		byte
 
 ;;;;; CARTRIDGE FILE HEADER
 
+NES_MAP_HORIZ	equ	0
+NES_MAP_VERT	equ	1
+NES_MAP_QUAD	equ	8
+
+	MAC NES_HEADER
 	processor 6502
 	seg Header
         org $7FF0
-
-NES_MAPPER	equ 0	;mapper number
-NES_PRG_BANKS	equ 2	;number of 16K PRG banks, change to 2 for NROM256
-NES_CHR_BANKS	equ 1	;number of 8K CHR banks (0 = RAM)
-NES_MIRRORING	equ 1	;0 horizontal, 1 vertical, 8 four screen
-
-	.byte $4e,$45,$53,$1a ; header
-	.byte NES_PRG_BANKS
-	.byte NES_CHR_BANKS
-	.byte NES_MIRRORING|(NES_MAPPER<<4)
-	.byte NES_MAPPER&$f0
-	.byte 0,0,0,0,0,0,0,0 ; reserved, set to zero
-
-;;;;; CODE
-
+.NES_MAPPER	SET {1}	;mapper number
+.NES_PRG_BANKS	SET {2}	;number of 16K PRG banks, change to 2 for NROM256
+.NES_CHR_BANKS	SET {3}	;number of 8K CHR banks (0 = RAM)
+.NES_MIRRORING	SET {4}	;0 horizontal, 1 vertical, 8 four screen
+	byte $4e,$45,$53,$1a ; header
+	byte .NES_PRG_BANKS
+	byte .NES_CHR_BANKS
+	byte .NES_MIRRORING|(.NES_MAPPER<<4)
+	byte .NES_MAPPER&$f0
+	byte 0,0,0,0,0,0,0,0 ; reserved, set to zero
 	seg Code
 	org $8000
-start:
-_exit:
+	ENDM
+        
+        MAC NES_INIT
         sei			;disable IRQs
         cld			;decimal mode not supported
         ldx #$ff
@@ -51,22 +54,18 @@ _exit:
         stx PPU_MASK		;disable rendering
         stx DMC_FREQ		;disable DMC interrupts
         stx PPU_CTRL		;disable NMI interrupts
-        jsr WaitSyncSafe	;wait for VSYNC
-; clear RAM -- not a subroutine because we clear the stack too
-	lda #0
-        tax
-.clearRAM
-	sta $0,x
-	sta $100,x
-        ; skip $200-$2FF, used for OAM display list
-	sta $300,x
-	sta $400,x
-	sta $500,x
-	sta $600,x
-	sta $700,x
-        inx
-        bne .clearRAM
-; end of clear RAM routine
+	bit PPU_STATUS		;clear VBL flag
+        ENDM
+
+	NES_HEADER 0,2,1,1 ; mapper 0, 2 PRGs, 1 CHR, vertical
+
+start:
+_exit:
+	NES_INIT		; set up stack pointer, turn off PPU
+        jsr WaitSync
+        jsr WaitSync
+        jsr ClearRAM
+        jsr WaitSync		;wait for VSYNC
 	jsr SetPalette		;set colors
         jsr FillVRAM		;set PPU RAM
         jsr WaitSync		;wait for VSYNC (and PPU warmup)
@@ -84,7 +83,27 @@ _exit:
 
 ;;;;; SUBROUTINES
 
+ClearRAM: subroutine
+	lda #0
+        tax
+.clearRAM
+	sta $0,x
+        cpx #$fe	; don't clear last 2 bytes of stack
+        bcs .skipStack
+	sta $100,x
+.skipStack
+        ; skip $200-$2FF, used for OAM display list
+	sta $300,x
+	sta $400,x
+	sta $500,x
+	sta $600,x
+	sta $700,x
+        inx
+        bne .clearRAM
+        rts
+
 ; set palette colors
+
 SetPalette: subroutine
         ldy #$0
 	lda #$3f
@@ -108,7 +127,7 @@ FillVRAM: subroutine
 	ldy #$10
 .loop:
 	sta PPU_DATA
-        adc #1
+        adc #7
 	inx
 	bne .loop
 	dey
@@ -116,8 +135,6 @@ FillVRAM: subroutine
         rts
 
 ; wait for VSYNC to start
-WaitSyncSafe: subroutine
-	bit PPU_STATUS
 WaitSync:
 	bit PPU_STATUS
 	bpl WaitSync
diff --git a/src/baseplatform.ts b/src/baseplatform.ts
index 8fb987e0..28d3e0a8 100644
--- a/src/baseplatform.ts
+++ b/src/baseplatform.ts
@@ -255,25 +255,28 @@ function cpuStateToLongString_6502(c) : string {
        + " Y " + hex(c.Y)    + "     " + "SP " + hex(c.SP) + "\n";
 }
 
+var OPMETA_6502 = {
+  cycletime: [
+  7, 6, 0, 8, 3, 3, 5, 5, 3, 2, 2, 2, 4, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    6, 6, 0, 8, 3, 3, 5, 5, 4, 2, 2, 2, 4, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    6, 6, 0, 8, 3, 3, 5, 5, 3, 2, 2, 2, 3, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    6, 6, 0, 8, 3, 3, 5, 5, 4, 2, 2, 2, 5, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    0, 6, 0, 6, 3, 3, 3, 3, 2, 0, 2, 0, 4, 4, 4, 4,    2, 6, 0, 0, 4, 4, 4, 4, 2, 5, 2, 0, 0, 5, 0, 0,    2, 6, 2, 6, 3, 3, 3, 3, 2, 2, 2, 0, 4, 4, 4, 4,    2, 5, 0, 5, 4, 4, 4, 4, 2, 4, 2, 0, 4, 4, 4, 4,    2, 6, 0, 8, 3, 3, 5, 5, 2, 2, 2, 2, 4, 4, 3, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    2, 6, 0, 8, 3, 3, 5, 5, 2, 2, 2, 0, 4, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7
+  ],
+  extracycles: [
+  0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1
+  ],
+  insnlengths: [
+  1, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    3, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    1, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    1, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    0, 2, 0, 2, 2, 2, 2, 2, 1, 0, 1, 0, 3, 3, 3, 3,    2, 2, 0, 0, 2, 2, 2, 3, 1, 3, 1, 0, 0, 3, 0, 0,    2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 0, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 1, 0, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 0, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3
+  ],
+  validinsns: [
+  1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 0, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    3, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    0, 2, 0, 0, 2, 2, 2, 0, 1, 0, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 3, 1, 0, 0, 3, 0, 0,    2, 2, 2, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 3, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0
+  ],
+}
+
 function getOpcodeMetadata_6502(opcode, address) {
-  var cycletime = [
-    7, 6, 0, 8, 3, 3, 5, 5, 3, 2, 2, 2, 4, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    6, 6, 0, 8, 3, 3, 5, 5, 4, 2, 2, 2, 4, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    6, 6, 0, 8, 3, 3, 5, 5, 3, 2, 2, 2, 3, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    6, 6, 0, 8, 3, 3, 5, 5, 4, 2, 2, 2, 5, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    0, 6, 0, 6, 3, 3, 3, 3, 2, 0, 2, 0, 4, 4, 4, 4,    2, 6, 0, 0, 4, 4, 4, 4, 2, 5, 2, 0, 0, 5, 0, 0,    2, 6, 2, 6, 3, 3, 3, 3, 2, 2, 2, 0, 4, 4, 4, 4,    2, 5, 0, 5, 4, 4, 4, 4, 2, 4, 2, 0, 4, 4, 4, 4,    2, 6, 0, 8, 3, 3, 5, 5, 2, 2, 2, 2, 4, 4, 3, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7,    2, 6, 0, 8, 3, 3, 5, 5, 2, 2, 2, 0, 4, 4, 6, 6,    2, 5, 0, 8, 4, 4, 6, 6, 2, 4, 0, 7, 4, 4, 7, 7
-  ];
-  var extracycles = [
-    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1,    0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,    2, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1
-  ];
-  var insnlengths = [
-    1, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    3, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    1, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    1, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    0, 2, 0, 2, 2, 2, 2, 2, 1, 0, 1, 0, 3, 3, 3, 3,    2, 2, 0, 0, 2, 2, 2, 3, 1, 3, 1, 0, 0, 3, 0, 0,    2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 0, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 1, 0, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 2, 1, 0, 3, 3, 3, 3,    2, 2, 0, 2, 2, 2, 2, 2, 1, 3, 0, 3, 3, 3, 3, 3
-  ];
-  var validinsns = [
-    1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 0, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    3, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    1, 2, 0, 0, 0, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    0, 2, 0, 0, 2, 2, 2, 0, 1, 0, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 3, 1, 0, 0, 3, 0, 0,    2, 2, 2, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 3, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0,    2, 2, 0, 0, 2, 2, 2, 0, 1, 2, 1, 0, 3, 3, 3, 0,    2, 2, 0, 0, 0, 2, 2, 0, 1, 3, 0, 0, 0, 3, 3, 0
-  ];
   // TODO: more intelligent maximum cycles
   return {
     opcode:opcode,
-    minCycles:cycletime[opcode],
-    maxCycles:cycletime[opcode] + extracycles[opcode],
-    insnlength:insnlengths[opcode]
+    minCycles:OPMETA_6502.cycletime[opcode],
+    maxCycles:OPMETA_6502.cycletime[opcode] + OPMETA_6502.extracycles[opcode],
+    insnlength:OPMETA_6502.insnlengths[opcode]
   };
 }
 
diff --git a/src/platform/nes.js b/src/platform/nes.js
index 49dd5bbd..43994521 100644
--- a/src/platform/nes.js
+++ b/src/platform/nes.js
@@ -83,9 +83,10 @@ var JSNESPlatform = function(mainElement) {
       //onBatteryRamWrite
     });
     nes.stop = function() {
-      self.pause();// TODO
-      console.log(nes.cpu.toJSON()); // TODO
-      throw ("CPU STOPPED");
+      // TODO: trigger breakpoint
+      self.pause();
+      console.log(nes.cpu.toJSON());
+      throw ("CPU STOPPED @ PC $" + hex(nes.cpu.REG_PC));
     };
     // insert debug hook
     nes.cpu._emulate = nes.cpu.emulate;
@@ -199,8 +200,7 @@ var JSNESPlatform = function(mainElement) {
     ];
     for (var i=0; i<PPUFLAGS.length; i++) {
       var flag = PPUFLAGS[i];
-      //if (ppu[flag[0]]) s += flag[1] + "\n";
-      s += (flag[1] ? flag[1] : "-") + " ";
+      s += (ppu[flag[0]] ? flag[1] : "-") + " ";
       if (i==2 || i==5) s += "\n";
     }
     s += "\n";
diff --git a/src/ui.ts b/src/ui.ts
index 2260c210..3e2614c4 100644
--- a/src/ui.ts
+++ b/src/ui.ts
@@ -393,24 +393,19 @@ function setCompileOutput(data: WorkerResult) {
     var rom = data.output;
     if (rom) { // TODO instanceof Uint8Array) {
       try {
-        //console.log("Loading ROM length", rom.length);
         platform.loadROM(getCurrentPresetTitle(), rom);
         if (!userPaused) resume();
         current_output = rom;
-        //resetProfiler();
+        // TODO: reset profiler etc? (Tell views?)
       } catch (e) {
         console.log(e);
         toolbar.addClass("has-errors");
-        projectWindows.setErrors([{line:0,msg:e+""}]);
+        projectWindows.setErrors([{line:1,msg:e+""}]); // TODO: doesn't work
         current_output = null;
       }
-    /* TODO?
-    } else if (rom.program_rom_variable) { //TODO: a little wonky...
-      platform.loadROM(rom.program_rom_variable, rom.program_rom);
-    */
     }
     // update all windows (listings)
-    projectWindows.refresh();
+    projectWindows.refresh(false);
   }
 }
 
@@ -457,7 +452,7 @@ function setupBreakpoint(btnid? : string) {
   platform.setupDebug(function(state) {
     lastDebugState = state;
     showDebugInfo(state);
-    projectWindows.refresh();
+    projectWindows.refresh(true);
     if (btnid) setDebugButtonState(btnid, "stopped");
   });
   if (btnid) setDebugButtonState(btnid, "active");
@@ -488,7 +483,7 @@ function _resume() {
 function resume() {
   clearBreakpoint();
   if (! platform.isRunning() ) {
-    projectWindows.refresh();
+    projectWindows.refresh(false);
   }
   _resume();
   userPaused = false;
@@ -664,7 +659,7 @@ function _openBitmapEditor() {
 }
 
 function traceTiming() {
-  projectWindows.refresh();
+  projectWindows.refresh(false);
   var wnd = projectWindows.getActive();
   if (wnd.getSourceFile && wnd.setGutterBytes) { // is editor active?
     showLoopTimingForPC(0, wnd.getSourceFile(), wnd);
diff --git a/src/views.ts b/src/views.ts
index 008b8c2b..d19539a1 100644
--- a/src/views.ts
+++ b/src/views.ts
@@ -7,7 +7,7 @@ import { Platform } from "./baseplatform";
 
 export interface ProjectView {
   createDiv(parent:HTMLElement, text:string) : HTMLElement;
-  refresh() : void;
+  refresh(moveCursor:boolean) : void;
   tick?() : void;
   getValue?() : string;
   getCursorPC?() : number;
@@ -153,7 +153,7 @@ export class SourceEditor implements ProjectView {
   
   clearErrors() {
     this.editor.clearGutter("gutter-info");
-    this.refreshDebugState();
+    this.refreshDebugState(false);
     this.dirtylisting = true;
     // clear line widgets
     this.errormsgs = [];
@@ -199,7 +199,7 @@ export class SourceEditor implements ProjectView {
     this.editor.setGutterMarker(line-1, "gutter-bytes", textel);
   }
   
-  setCurrentLine(line:number) {
+  setCurrentLine(line:number, moveCursor:boolean) {
 
     var addCurrentMarker = (line:number) => {
       var div = document.createElement("div");
@@ -211,7 +211,8 @@ export class SourceEditor implements ProjectView {
     this.clearCurrentLine();
     if (line>0) {
       addCurrentMarker(line-1);
-      this.editor.setSelection({line:line,ch:0}, {line:line-1,ch:0}, {scroll:true});
+      if (moveCursor)
+        this.editor.setSelection({line:line,ch:0}, {line:line-1,ch:0}, {scroll:true});
       this.currentDebugLine = line;
     }
   }
@@ -224,14 +225,14 @@ export class SourceEditor implements ProjectView {
     }
   }
   
-  refreshDebugState() {
+  refreshDebugState(moveCursor:boolean) {
     this.clearCurrentLine();
     var state = lastDebugState;
     if (state && state.c) {
       var PC = state.c.PC;
       var line = this.sourcefile.findLineForOffset(PC);
       if (line >= 0) {
-        this.setCurrentLine(line);
+        this.setCurrentLine(line, moveCursor);
         // TODO: switch to disasm?
       }
     }
@@ -246,9 +247,9 @@ export class SourceEditor implements ProjectView {
     }
   }
 
-  refresh() {
+  refresh(moveCursor: boolean) {
     this.refreshListing();
-    this.refreshDebugState();
+    this.refreshDebugState(moveCursor);
   }
   
   getLine(line : number) {
@@ -368,7 +369,7 @@ export class DisassemblerView implements ProjectView {
   }
 
   // TODO: too many globals
-  refresh() {
+  refresh(moveCursor: boolean) {
     var state = lastDebugState || platform.saveState();
     var pc = state.c ? state.c.PC : 0;
     var curline = 0;
@@ -407,8 +408,10 @@ export class DisassemblerView implements ProjectView {
     }
     var text = disassemble(pc-96, pc) + disassemble(pc, pc+96);
     this.disasmview.setValue(text);
-    this.disasmview.setCursor(selline, 0);
-    jumpToLine(this.disasmview, selline);
+    if (moveCursor) {
+      this.disasmview.setCursor(selline, 0);
+      jumpToLine(this.disasmview, selline);
+    }
   }
 
   getCursorPC() : number {
@@ -434,7 +437,7 @@ export class ListingView extends DisassemblerView implements ProjectView {
     this.assemblyfile = assemblyfile;
   }
 
-  refresh() {
+  refresh(moveCursor: boolean) {
     var state = lastDebugState || platform.saveState();
     var pc = state.c ? state.c.PC : 0;
     var asmtext = this.assemblyfile.text;
@@ -447,7 +450,7 @@ export class ListingView extends DisassemblerView implements ProjectView {
     var findPC = platform.getDebugCallback() ? pc : -1;
     if (findPC >= 0) {
       var lineno = this.assemblyfile.findLineForOffset(findPC);
-      if (lineno) {
+      if (lineno && moveCursor) {
         // set cursor while debugging
         if (platform.getDebugCallback())
           disasmview.setCursor(lineno-1, 0);
diff --git a/src/windows.ts b/src/windows.ts
index 0efb48e0..027635c5 100644
--- a/src/windows.ts
+++ b/src/windows.ts
@@ -45,7 +45,7 @@ export class ProjectWindows {
       this.activediv = div;
       this.activewnd = wnd;
       $(div).show();
-      this.refresh();
+      this.refresh(true);
       this.refreshErrors();
     }
     this.activeid = id;
@@ -56,9 +56,9 @@ export class ProjectWindows {
     this.id2window[id] = window;
   }
   
-  refresh() {
+  refresh(moveCursor:boolean) {
     if (this.activewnd && this.activewnd.refresh)
-      this.activewnd.refresh();
+      this.activewnd.refresh(moveCursor);
   }
   
   tick() {