Almost !


Here is the new code:


ERASECODE $1F00


For BB = $1F00 to $1F3F STEP 2
WRITECODE BB,$5555
NEXT BB

For CC = $1F00 to $1F3F STEP 2
READCODE CC,DD
HSEROUT [HEX4 CC," ",HEX4 DD,13,10]
NEXT CC


And here is the output:

1F00 FFFF
1F02 FFFF
1F04 FFFF
1F06 FFFF
1F08 FFFF
1F0A FFFF
1F0C FFFF
1F0E FFFF
1F10 FFFF
1F12 FFFF
1F14 FFFF
1F16 FFFF
1F18 FFFF
1F1A FFFF
1F1C FFFF
1F1E FFFF
1F20 FFFF
1F22 FFFF
1F24 FFFF
1F26 FFFF
1F28 FFFF
1F2A FFFF
1F2C FFFF
1F2E FFFF
1F30 FFFF
1F32 FFFF
1F34 FFFF
1F36 FFFF
1F38 5555
1F3A 5555
1F3C 5555
1F3E 5555


I get the same result if I use "ERASECODE $7C" ($1F00/$3F)