10 REM Test CGA graphics framebuffer PEEK/POKE
20 SCREEN 1
30 DEF SEG = &HB800
40 REM POKE a byte at offset 0 (even row 0, first 4 pixels)
50 POKE 0, &HFF
60 V = PEEK(0)
70 PRINT "POKE FF PEEK="; V
80 REM POKE at odd row bank (offset 0x2000)
90 POKE &H2000, &HAA
100 V = PEEK(&H2000)
110 PRINT "ODD ROW PEEK="; V
120 REM Clear and verify
130 POKE 0, 0
140 PRINT "CLEARED="; PEEK(0)
150 SCREEN 0
160 DEF SEG
170 PRINT "DONE"