diff --git a/blk/581 b/blk/581
index b6e6a98..c54687a 100644
--- a/blk/581
+++ b/blk/581
@@ -2,15 +2,11 @@ ACIA driver
 
 Manage I/O from an asynchronous communication interface adapter
 (ACIA). provides "(emit)" to put c char on the ACIA as well as
-an input buffer from which a provided "(key)" reads. You have
-to call "~ACIA" on interrupt for this module to work well.
+an input buffer from which a provided "(key)" reads. This driver
+installs an interrupt handler at RST38 to handle RX.      
 
-CONFIGURATION
+To use, begin by loading declarations (B582) before xcomp is    
+loaded. These declarations provide default values for ports and 
+memory offsets that you can override. See B582.
 
-ACIA_CTL: IO port for the ACIA's control registers
-ACIA_IO: IO port for the ACIA's data registers
-ACIA_MEM: Address in memory that can be used variables shared
-          with ACIA's native words. 8 bytes used.
-
-The whole driver is cross-compilable and is loaded with
-"582 LOAD"
+Then, in the driver part, load range 583-588.
diff --git a/blk/582 b/blk/582
index 54933a8..91de737 100644
--- a/blk/582
+++ b/blk/582
@@ -1,7 +1,15 @@
-( Memory layout
-  +0 ACIAR>
-  +2 ACIAW>
-  +4 ACIA(
-  +6 ACIA) )
-
-1 6 LOADR+
+0x80 CONSTANT ACIA_CTL ( IO port for ACIA's control register )
+0x81 CONSTANT ACIA_IO ( IO port for ACIA's data registers )
+( Address in memory that can be used variables shared
+  with ACIA's native words. 8 bytes used. )
+CREATE ACIA_MEM RAMSTART 0x70 + ,
+( Points to ACIA buf )
+: ACIA( ACIA_MEM @ 4 + ;
+( Points to ACIA buf end )
+: ACIA) ACIA_MEM @ 6 + ;
+( Read buf pointer. Pre-inc )
+: ACIAR> ACIA_MEM @ ;
+( Write buf pointer. Post-inc )
+: ACIAW> ACIA_MEM @ 2+ ;
+( This means that if W> == R>, buffer is full.
+  If R>+1 == W>, buffer is empty. )
diff --git a/blk/583 b/blk/583
index 6f49f02..1bac543 100644
--- a/blk/583
+++ b/blk/583
@@ -5,10 +5,9 @@
     0x01 ANDi,   ( is ACIA rcv buf full? )
     IFNZ,
         ( correct interrupt cause )
-        ( +2 == ACIAW> )
-        ACIA_MEM 2+ LDHL(n),
+        ACIAW> LDHL(n),
         ( is it == to ACIAR>? )
         ( +0 == ACIAR> )
-        DE ACIA_MEM LDdd(n),
+        DE ACIAR> LDdd(n),
         ( carry cleared from ANDi above )
         DE SBCHLd,                                    ( cont. )
diff --git a/blk/584 b/blk/584
index d2b0515..5ccb3b2 100644
--- a/blk/584
+++ b/blk/584
@@ -6,10 +6,8 @@
             (HL) A LDrr,
             ( advance W> )
             HL INCd,
-            ( +2 == ACIAW> )
-            ACIA_MEM 2+ LD(n)HL,
-            ( +6 == ACIA) )
-            DE ACIA_MEM 6 + LDdd(n),
+            ACIAW> LD(n)HL,
+            DE ACIA) LDdd(n),
             DE SUBHLd,
 
 
diff --git a/blk/585 b/blk/585
index 2b2a8ae..f8b5738 100644
--- a/blk/585
+++ b/blk/585
@@ -1,9 +1,7 @@
             IFZ, ( end of buffer reached? )
                 ( yes )
-                ( +4 == ACIA( )
-                ACIA_MEM 4 + LDHL(n),
-                ( +2 == ACIAW> )
-                ACIA_MEM 2+ LD(n)HL,
+                ACIA( LDHL(n),
+                ACIAW> LD(n)HL,
             THEN,
         THEN,
     THEN,
diff --git a/blk/586 b/blk/586
deleted file mode 100644
index a236b96..0000000
--- a/blk/586
+++ /dev/null
@@ -1,10 +0,0 @@
-( Points to ACIA buf )
-: ACIA( [ ACIA_MEM 4 + LITN ] ;
-( Points to ACIA buf end )
-: ACIA) [ ACIA_MEM 6 + LITN ] ;
-( Read buf pointer. Pre-inc )
-: ACIAR> [ ACIA_MEM LITN ] ;
-( Write buf pointer. Post-inc )
-: ACIAW> [ ACIA_MEM 2 + LITN ] ;
-( This means that if W> == R>, buffer is full.
-  If R>+1 == W>, buffer is empty. )
diff --git a/blk/587 b/blk/587
index bd73fd4..9b91d38 100644
--- a/blk/587
+++ b/blk/587
@@ -1,12 +1,12 @@
 : (key)
     ( inc then fetch )
-    ACIAR> @ 1+ DUP ACIA) @ = IF
-        DROP ACIA( @
+    [ ACIAR> LITN ] @ 1+ DUP [ ACIA) LITN ] @ = IF
+        DROP [ ACIA( LITN ] @
     THEN
     ( As long as R> == W>-1, it means that buffer is empty )
-    BEGIN DUP ACIAW> @ = NOT UNTIL
-    ACIAR> !
-    ACIAR> @ C@
+    BEGIN DUP [ ACIAW> LITN ] @ = NOT UNTIL
+    [ ACIAR> LITN ] !
+    [ ACIAR> LITN ] @ C@
 ;
 : (emit)
     ( As long at CTL bit 1 is low, we are transmitting. wait )
diff --git a/blk/588 b/blk/588
index 41a635a..7b11043 100644
--- a/blk/588
+++ b/blk/588
@@ -1,8 +1,8 @@
 : ACIA$
-    H@ DUP DUP ACIA( ! ACIAR> !
-    1+ ACIAW> !  ( write index starts one position later )
+    H@ DUP DUP [ ACIA( LITN ] ! [ ACIAR> LITN ] !
+    1+ [ ACIAW> LITN ] ! ( write index starts one pos later )
     0x20 ( buffer size ) ALLOT
-    H@ ACIA) !
+    H@ [ ACIA) LITN ] !
 ( setup ACIA
   CR7 (1) - Receive Interrupt enabled
   CR6:5 (00) - RTS low, transmit interrupt disabled.
diff --git a/blk/618 b/blk/618
index ab903a7..83d6047 100644
--- a/blk/618
+++ b/blk/618
@@ -1,13 +1,12 @@
 0x8000 CONSTANT RAMSTART
 0xff00 CONSTANT RS_ADDR        0xfffa CONSTANT PS_ADDR
-0x80   CONSTANT ACIA_CTL       0x81   CONSTANT ACIA_IO
 4      CONSTANT SDC_SPI
 5      CONSTANT SDC_CSLOW      6      CONSTANT SDC_CSHIGH
-RAMSTART 0x70 + CONSTANT ACIA_MEM
+582 LOAD  ( acia decl )
 212 LOAD  ( z80 assembler )
 262 LOAD  ( xcomp )            282 LOAD  ( boot.z80.decl )
 270 LOAD  ( xcomp overrides )  283 335 LOADR ( boot.z80 )
-353 LOAD  ( xcomp core low )   582 LOAD  ( acia )
+353 LOAD  ( xcomp core low )   583 588 LOADR ( acia )
 380 LOAD  ( xcomp core high )
 (entry) _
 ( Update LATEST )