Display window upper bits for start, stop
This is an added register for Hires chips, and allows larger start & stop ranges. If it is not written, (DIWSTRT, DIWSTOP) 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | H10 | H1 | H0 | V10 | V9 | V8 | 0 | 0 | H10 | H1 | H0 | V10 | V9 | V8 | |
| (stop) | (start) |
H1 and H0 values define 70ns and 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.