This is an added register for Hires chips, and allows
larger start & stop ranges. If it is not written, the above
(DIWSTRT, STOP) description holds. If
this register is written, direct start & stop positions
anywhere on the screen. It doesn`t affect the UHRES pointers.
BIT# 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
X X H10 H1 H0 V10 V9 V8 X X H10 H1 H0 V10 V9 V8
(stop) | (start)
Take care (X) bits should always be written to 0 to
maintain upwards compatibility. H1 and H0 values define
70ns amd 35ns increments respectively, and new LISA bits.
Note: In all 3 display window registers, horizontal bit
positions have been renamed to reflect HIRES pixel
increments, e.g. what used to be called H0 is now
referred to as H2.