So reading the RKM and it's starting to make sense. What was throwing me was the 8 bits between address locations, and the fact it was doubled for the resolution.
Until I read this:
Code:
Recall that the hardware resolution of display window start and stop is twice the hardware resolution of data fetch
So I redid that table to help
Code:
Data Fetch: 0 8 16 24 32 40 48 56 64 72 80 88 96 104 112 120 128 136 144 152 160
DW Start/Stop: 0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 256 272 288 304 320
Address Locations: $38 $40 $48 $50 $58 $60 $68 $70 $78 $80 $88 $90 $98 $a0 $a8 $b0 $b8 $c0 $c8 $d0 $d8
x1 fetch mode: SRT | | | | | | | | | | | | | | | | | | | |STP
x2 fetch mode: SRT | | | | | | | | | |STP
x4 fetch mode: SRT | | | | |STP