VPOSR

 BIT#  15  14  13  12  11  10  09  08     07  06  05  04  03  02  01  00
 USE LOF   I6  I5  I4  I3  I2  I1  I0 LOL --  --  --  --  --  V10 V9  V8

LOF = Long frame(auto toggle control bit in BPLCON0)
I0-I6 Chip identitication:
8361 (Regular) or 8370 (Fat) (Agnus-ntsc) = 10 8367 (Pal) or 8371 (Fat-Pal) (Agnus-pal) = 00 8372 (Fat-hr) (agnushr),thru rev4 = 20 Pal, 30 NTSC 8372 (Fat-hr) (agnushr),rev 5 = 21 Pal, 31 NTSC 8374 (Alice) thru rev 2 = 22 Pal, 32 NTSC 8374 (Alice) rev 3 thru rev 4 = 23 Pal, 33 NTSC
LOL = Long line bit. When low, it indicates short raster line. v9,10 -- hires chips only (20,30 identifiers)
SEE ALSO: VHPOSR and VHPOSW
Interesting links: