=== 10bit Config Value ===
The Z80's 8bit databus doesn't allow to write 10bit values. The ARA is using a rather strange solution to overcome that problem. The mechanism to set Config=N is:
OUT [F9F5h],garbage, FOR I=1 to N, OUT [FAF5h],garbage, NEXT I
Whereas, the separate bits in "N" are:
0-1 Contrast
2-5 Brightness