Address Name Description
DFF1C4 HBSTRT Horizontal START position
DFF1C6 HBSTOP Horizontal STOP position


Bits 7-0 contain the stop and start positions, respectively,
for programmed horizontal blanking in 280ns increments.
Bits 10-8 provide a fine position control in 35ns increments.

Bit Function Description
15-11 0 Unused
10 H1 140ns
09 H1 70ns
08 H0 35ns
07 H10 35840ns
06 H9 17920ns
05 H8 8960ns
04 H7 4480ns
03 H6 2240ns
02 H5 1120ns
01 H4 560ns
00 H3 280ns
This material is most likely derived from the official Amiga documentation and where applicable copyright remains with the original author.