You can either register 0 - 3. Register 3 is only available in ESC/P2 mode.
The command ESC ( t can be used to assign character sets to character table (d1). If d1 = 2 you cannot use
Example 10 REM upper half of code table
20LPRINT CHR$(27);"t0";
30GOSUB 90
40LPRINT CHR$(27);"t1";
50GOSUB 90
60LPRINT CHR$(27);"t2";
70GOSUB 90
80END
90RESTORE
100FOR I = 1 TO 15
110READ D
120LPRINT CHR$(D);
130NEXT I
140LPRINT
150RETURN
160DATA 65,66,67,68,69,165,166,167,168,169,170,171,172,173,174