ACT apricot - Page 260

SCREEN DRIVER
4. How a character appears on the screen
The CRTC controller chip will generate a word address in
the screen buffer memory. A part of each word contains the
attributes, which are stripped off and passed to the video
control logic
to be used later. The whole word at this
address is then passed into the video shift register, which
passes the word (as serial information) to the video output
controller, where it is re-united with the (now processed)
attribute data and then converted to a series of raw on/off
pulses ready for
the CRT - after merging them with
horizontal & vertical sync signals.