diff --git a/sid.4th b/sid.4th
index 5d4b2ce..afeba7e 100644
--- a/sid.4th
+++ b/sid.4th
@@ -1,16 +1,23 @@
 ( --- Gforth SID chip stub --- )
 
-( : SID! SWAP . . ." SID! " ; )
+( : PC! DUP 255 AND . 8 RSHIFT .  . CR ; )
 ( : >< DUP 8 RSHIFT SWAP 8 LSHIFT 65534 AND OR ; )
 
-( --- SID chip access --- )
+( --- Library --- )
 
 : PC2!   ( b b p-addr -- ) ( Data byte A, high address byte B, port address C )
    SWAP >< OR PC! ;
+: BIT    ( n -- ) ( define bit flag )
+   1 SWAP LSHIFT CONSTANT ;
+: BIT+    ( n -- n+1 ) ( define bit flag and next )
+   DUP 1+ SWAP BIT ;
+
+( --- SID chip access --- )
+
 : SID!   ( b n0-31 -- ) ( Send byte to SID { 1data , 4?register | 2?interrupt } ) 
-  2DUP 128 OR 84 PC2!
-  2DUP 127 AND 84 PC2!
-  128 OR 84 PC2! ;
+   2DUP 128 OR 84 PC2!
+   2DUP 127 AND 84 PC2!
+   128 OR 84 PC2! ;
 
 ( --- Voice selection --- )
 
@@ -30,14 +37,15 @@ CREATE >VOICE-CTL VOICE-CTLS ,
 
 ( --- SID chip control register flags --- )
 
-: GATE   1 ;
-: SYNC   2 ;
-: RING   4 ;
-: TEST   8 ;
-: TRI   16 ;
-: SAW   32 ;
-: PWM   64 ;
-: NOISE   128 ;
+0 BIT+ GATE
+  BIT+ SYNC
+  BIT+ RING
+  BIT+ TEST
+  BIT+ TRI
+  BIT+ SAW
+  BIT+ PWM
+  BIT+ NOISE
+DROP
 
 ( --- Voice register operation --- )
 
@@ -69,15 +77,16 @@ CREATE >VOICE-CTL VOICE-CTLS ,
 ( Reg 23 - { 4?filter-resonance [0-15] | 1?ext | 1?voice-2 | 1?voice-1 | 1?voice-0 } )
 : RES   ( n0-15 -- b )   15 AND 4 LSHIFT ;
 : VOICE-FILTER   ( voice -- b )  1 SWAP LSHIFT ;
-: EXT   8 ;
+3 BIT EXT-FILTER
 : RES|FILTER!   ( b -- )  23 SID! ;
 
 ( Reg 24 - { 1?mute-voice-3 | 1?highpass | 1?bandpass | 1?lowpass | 4?volume )
 : VOLUME   ( n0-15 -- b )  15 AND ;
-: LOWPASS   16 ;
-: BANDPASS   32 ;
-: HIGHPASS   64 ;
-: MUTE-VOICE3   128 ;
+4 BIT+ LOWPASS
+  BIT+ BANDPASS
+  BIT+ HIGHPASS
+  BIT+ MUTE-VOICE3
+DROP
 : MODE|VOLUME!   24 SID! ;
 
 ( --- Frequency table --- )
@@ -119,7 +128,7 @@ CREATE TEMPO 40000 ,
 : DELAY   ( delay -- ) 0 DO LOOP ;
 : PAUSE   ( delay -- ) DUP DELAY DELAY ;
 
-: PLAY START DUP DELAY DELAY STOP ;
+: PLAY START DUP PAUSE STOP ;
 
 ( --- Test --- )