diff --git a/constants/SP2000.inc b/constants/SP2000.inc
index 8ed0f8e..a1215ab 100644
--- a/constants/SP2000.inc
+++ b/constants/SP2000.inc
@@ -731,6 +731,7 @@ CMOS.Cell.ScreenSET     EQU     #1A
 ;
 CMOS.USED_MAX_ADDRESS	EQU	#3F
 CMOS.MAX_ADDRESS	EQU	#7F
+CMOS.TEST_CELL		EQU	CMOS.MAX_ADDRESS
 
 GR_BIT_END		EQU 7