diff --git a/res/c64.wasm b/res/c64.wasm
index fc6130e3..12cbb44d 100755
Binary files a/res/c64.wasm and b/res/c64.wasm differ
diff --git a/res/cpc.wasm b/res/cpc.wasm
index addbab44..0c90c5bb 100755
Binary files a/res/cpc.wasm and b/res/cpc.wasm differ
diff --git a/res/zx.wasm b/res/zx.wasm
index 56e54573..502c3e5f 100755
Binary files a/res/zx.wasm and b/res/zx.wasm differ
diff --git a/src/machine/c64.ts b/src/machine/c64.ts
index 5d2216bc..8acfcee4 100644
--- a/src/machine/c64.ts
+++ b/src/machine/c64.ts
@@ -79,11 +79,12 @@ export class C64_WASMMachine extends BaseWASMMachine implements Machine, Probeab
     // TODO: does this sync with VSYNC?
     // TODO: ticks, not msec (machine_tick() has different rate then machine_exec())
     var scanline = this.getRasterY();
-    var clocks = Math.floor((this.numTotalScanlines - scanline) * (19656+295) / this.numTotalScanlines);
+    var clocks = Math.floor((this.numTotalScanlines - scanline) * 19656 / this.numTotalScanlines);
     var probing = this.probe != null;
     if (probing) this.exports.machine_reset_probe_buffer();
     clocks = super.advanceFrameClock(trap, clocks);
     if (probing) this.copyProbeData();
+    //console.log(clocks, this.getRasterY());
     return clocks;
   }
   getCPUState() {
diff --git a/src/machine/cpc.ts b/src/machine/cpc.ts
index 83fda7fa..c66be66e 100644
--- a/src/machine/cpc.ts
+++ b/src/machine/cpc.ts
@@ -59,7 +59,7 @@ export class CPC_WASMMachine extends BaseWASMMachine implements Machine {
   }
   advanceFrame(trap: TrapCondition) : number {
     var scanline = this.getRasterY();
-    var clocks = Math.floor((this.numTotalScanlines - scanline) * 19965 / this.numTotalScanlines);
+    var clocks = Math.floor((this.numTotalScanlines - scanline) * (4000000/50) / this.numTotalScanlines);
     var probing = this.probe != null;
     if (probing) this.exports.machine_reset_probe_buffer();
     clocks = super.advanceFrameClock(trap, clocks);
diff --git a/src/machine/vic20.ts b/src/machine/vic20.ts
index 1e760813..2e7d6c40 100644
--- a/src/machine/vic20.ts
+++ b/src/machine/vic20.ts
@@ -74,7 +74,7 @@ export class VIC20_WASMMachine extends BaseWASMMachine implements Machine, Probe
   advanceFrame(trap: TrapCondition) : number {
     // TODO: does this sync with VSYNC?
     var scanline = this.getRasterY();
-    var clocks = Math.floor((this.numTotalScanlines - scanline) * (19656+295+32) / this.numTotalScanlines);
+    var clocks = Math.floor((this.numTotalScanlines - scanline) * 19656 / this.numTotalScanlines);
     var probing = this.probe != null;
     if (probing) this.exports.machine_reset_probe_buffer();
     clocks = super.advanceFrameClock(trap, clocks);
diff --git a/src/machine/zx.ts b/src/machine/zx.ts
index e9dc5f16..794216e7 100644
--- a/src/machine/zx.ts
+++ b/src/machine/zx.ts
@@ -20,7 +20,7 @@ export class ZX_WASMMachine extends BaseWASMMachine implements Machine {
   reset() {
     super.reset();
     // advance bios
-    this.exports.machine_exec(this.sys, 500000); // TODO?
+    this.exports.machine_exec(this.sys, 2000000);
     // load rom (Z80 header: https://worldofspectrum.org/faq/reference/z80format.htm)
     if (this.romptr && this.romlen) {
       // TODO
@@ -41,7 +41,7 @@ export class ZX_WASMMachine extends BaseWASMMachine implements Machine {
     //var scanline = this.exports.machine_get_raster_line(this.sys);
     var probing = this.probe != null;
     if (probing) this.exports.machine_reset_probe_buffer();
-    var clocks = super.advanceFrameClock(trap, Math.floor(1000000 / 50)); // TODO: use ticks, not msec
+    var clocks = super.advanceFrameClock(trap, Math.floor(3500000 / 50));
     if (probing) this.copyProbeData();
     return clocks;
   }