ACT apricot - Page 256

SCREEN DRIVER
13-CR
14-S0
15 -SI
Moves the cursor to the beginning of the
current line
Switches in the second character set
Selects the default character set
24 - CAN Cancels any escape sequence currently in
operation
27 -
ESC Herald the start of an escape sequence
Physical Screen Layout
The Apricot screen has a 4K byte block of memory which
acts as a screen buffer. This memory is located at FOOOO hex
and is utilised as follows:
For every
character on the screen, there is one word. The
first word in the screen buffer is for the first top left-hand
character
on the screen, the last word is for the bottom
right-hand character.
Word in The Apricot Screen Buffer:
second byte
first byte
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Ixlxlxlxlxlxlxlxlxlxlxlxlxlxlxlxl
l
l
L ____ Font Cell Pointer -----1
- Software Reserved
- Strikethrough
- Intensity
- Underline
- Reverse
The diagram above shows a graphical representation of a
word in the screen RAM. It should be noted that the
diagram is in high-low order, so the second byte shown
actually comes before first one shown. The attribute bits
have
the following functions: