CALL CHAR

100 CALL CLEAR
110 CALL CHAR(96, "FFFFFFFFFFFFFFFF")
120 CALL CHAR(42, "0F0F0F0F0F0F0F0F")
130 CALL HCHAR(12,17,42)
140 CALL VCHAR(14,17,96)
150 FOR DELAY=1 TO 500
160 NEXT DELAY

The first time I ever programmed it was from this page. And I made graphics in 8 by 8 squares on graph paper for months after that. Then I’d painstakingly convert these 8×8 blocks to hex on my TI-99/4a. Then turn that into code. Then enter that code on the computer. And then display them. It was magical.

Here’s the manual.

Here’s an emulator