Mr z: Protected "Picture Encoding" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

2010-12-04T09:05:56Z

Protected "Picture Encoding" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

Arnauld at 16:55, 31 January 2005

2005-01-31T16:55:57Z

New page

This article describes how pictures are encoded in graphics memory. This applies to [[Graphics RAM]] and [[Graphics ROM]].

Each card stores a single 8x8 picture in a sequence of 8 bytes. The first byte of the sequence holds the topmost row of pixels. The last byte holds the bottom row of pixels. Bit 7 in each byte holds the leftmost column of pixels, and bit 0 in each byte holds the rightmost column. Pictorally:

Bit #
7 6 5 4 3 2 1 0
+---------------+
0 | |
B 1 | |
y 2 | |
t 3 | |
e 4 | |
5 | |
# 6 | |
7 | |
+---------------+

Suppose, for instance, we want to define a picture for the letter R. That picture might look like so: ('#' indicates pixels that are "on", and '.' indicates pixels that are "off")

Bit #
7 6 5 4 3 2 1 0
+---------------+
0 |# # # # # # . .|
B 1 |. # # . . # # .|
y 2 |. # # . . # # .|
t 3 |. # # # # # . .|
e 4 |. # # . . # # .|
5 |. # # . . # # .|
# 6 |. # # . . # # .|
7 |# # # . . # # #|
+---------------+

All of the "on" pixels are represented with 1 bits, and all of the "off" pixels are represented with 0 bits. The binary pattern for this character would be:

DECLE %11111100
DECLE %01100110
DECLE %01100110
DECLE %01111100
DECLE %01100110
DECLE %01100110
DECLE %01100110
DECLE %11100111

You could copy this exact bit pattern into one of the card slots in GRAM, and voila! You have a stylized R.

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Picture Encoding - Revision history

Mr z: Protected "Picture Encoding" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

Arnauld at 16:55, 31 January 2005