This document explains the format of the Polymorphic VTI character blocks.
There are 16 rows and 64 columns of characters on the display.
Each block is 3 rows x 2 columns.
Left colum is high nibble, right column is low nibble.
Blocks in the colum are numbered bottom up.

Images can be formed using a combination of the blocks.

Bit numbering:
5 2
4 1
3 0

Bits 6 and 7 are always 0.

To write a character block to an address, you use two hex values to make one byte. Each address can hold one byte, and that corresponds to a character block in each address.

If a bit is on (1), the screen shows dark. If a bit is off, the screen is lit up. For example, hex 00 would be all 6 bits on in that character block.

Diagram of hex 00 (N for On, F for Off):
N N
N N
N N

Diagram of hex 15:
N F
F N
N F