diff --git a/arch/z80/sms/blk/608 b/arch/z80/sms/blk/608
index e04cde5..f3913e1 100644
--- a/arch/z80/sms/blk/608
+++ b/arch/z80/sms/blk/608
@@ -6,3 +6,6 @@
     ( sprite, inverted colors ) 0x3f _data 15 _zero
     0x4000 _ctl 0x5e 0 DO ~FNT I 7 * + _sfont LOOP
     ( bit 6, enable display, bit 7, ?? ) 0x81c0 _ctl ;
+
+: COLS 32 ;
+: LINES 24 ;
diff --git a/arch/z80/sms/xcomp.fs b/arch/z80/sms/xcomp.fs
index 822e36d..1768b6c 100644
--- a/arch/z80/sms/xcomp.fs
+++ b/arch/z80/sms/xcomp.fs
@@ -7,8 +7,6 @@ RS_ADDR 0x80 - CONSTANT SYSVARS
 0xbf   CONSTANT VDP_CTLPORT
 0xbe   CONSTANT VDP_DATAPORT
 SYSVARS 0x70 + CONSTANT GRID_MEM
-32     CONSTANT COLS
-24     CONSTANT ROWS
 SYSVARS 0x72 + CONSTANT CPORT_MEM
 0x3f   CONSTANT CPORT_CTL
 0xdc   CONSTANT CPORT_D1
diff --git a/arch/z80/sms/xcompkbd.fs b/arch/z80/sms/xcompkbd.fs
index f99e09f..467d36b 100644
--- a/arch/z80/sms/xcompkbd.fs
+++ b/arch/z80/sms/xcompkbd.fs
@@ -8,8 +8,6 @@ RS_ADDR 0x80 - CONSTANT SYSVARS
 0xbf   CONSTANT VDP_CTLPORT
 0xbe   CONSTANT VDP_DATAPORT
 SYSVARS 0x70 + CONSTANT GRID_MEM
-32     CONSTANT COLS
-24     CONSTANT ROWS
 SYSVARS 0x72 + CONSTANT CPORT_MEM
 0x3f   CONSTANT CPORT_CTL
 0xdc   CONSTANT CPORT_D1
diff --git a/arch/z80/sms/xcompsdc.fs b/arch/z80/sms/xcompsdc.fs
index 63bccbb..f4b3337 100644
--- a/arch/z80/sms/xcompsdc.fs
+++ b/arch/z80/sms/xcompsdc.fs
@@ -9,8 +9,6 @@ RS_ADDR 0x80 - CONSTANT SYSVARS
 0xbf   CONSTANT VDP_CTLPORT
 0xbe   CONSTANT VDP_DATAPORT
 SYSVARS 0x70 + CONSTANT GRID_MEM
-32     CONSTANT COLS
-24     CONSTANT ROWS
 SYSVARS 0x72 + CONSTANT CPORT_MEM
 0x3f   CONSTANT CPORT_CTL
 0xdc   CONSTANT CPORT_D1
diff --git a/blk/402 b/blk/402
index 753a778..ac94de5 100644
--- a/blk/402
+++ b/blk/402
@@ -1,10 +1,10 @@
 : XYPOS [ GRID_MEM LITN ] ;
-: AT-XY ( x y -- ) [ ROWS LITN ] * +
-    [ COLS ROWS * LITN ] MOD XYPOS ! ;
+: _cl* COLS LINES * ;
+: AT-XY ( x y -- ) LINES * + _cl* MOD XYPOS ! ;
 : _lf
     XYPOS @ BEGIN ( pos )
         0 ( blank ) SWAP TUCK CELL!
-        1+ DUP [ COLS LITN ] MOD NOT UNTIL
-    [ COLS ROWS * LITN ] MOD XYPOS ! ;
+        1+ DUP COLS MOD NOT UNTIL
+    _cl* MOD XYPOS ! ;
 : _bs 0 ( blank ) XYPOS @ TUCK CELL! ( pos ) 1-
-    [ COLS ROWS * LITN ] MOD XYPOS ! ;
+    _cl* MOD XYPOS ! ;
diff --git a/blk/403 b/blk/403
index 92413cb..284a357 100644
--- a/blk/403
+++ b/blk/403
@@ -3,5 +3,4 @@
     DUP 0x0d = IF DROP _lf EXIT THEN
     0x20 - DUP 0< IF DROP EXIT THEN
     XYPOS @ CELL!
-    XYPOS @ 1+ DUP [ COLS ROWS * LITN ]
-    = IF DROP 0 THEN XYPOS ! ;
+    XYPOS @ 1+ _cl* MOD XYPOS ! ;
diff --git a/doc/protocol.txt b/doc/protocol.txt
index b8cafef..f9caf31 100644
--- a/doc/protocol.txt
+++ b/doc/protocol.txt
@@ -43,11 +43,11 @@ A grid is a device that shows as a grid of ASCII characters and
 allows random access to it.
 
 COLS      -- n     Number of columns in the device
-ROWS      -- n     Number of rows in the device
+LINES     -- n     Number of lines in the device
 CELL!     g pos -- Set glyph at pos
 
 "pos" is a simple number (y * cols) + x. For example, if we
-have 40 columns per row, the position (x, y) (12, 10) is 412.
+have 40 columns per line, the position (x, y) (12, 10) is 412.
 
 A glyph is ASCII-0x20. If the resulting glyph number exceeds the
 number of glyphs in the font, it's up to CELL! to ignore it.