hi everyone, i have this 20x2 vfd that is driven by four uln5812 vfd drivers. each uln5812 is a 20 bit shift register. two of the drivers take care of the 40 grids, and the other two take care of the 35 segments (5x7 dot matrix). it took me all day to map the bits to segments/grids, and i shifted out static characters on individual grids.

here's where the fun starts; i need to scan the grids, and this is the approach im trying;
Code:
 grid var bit[40] 

500 hz interrupt routine pseudocode:
grid[40] = grid[40] << 1
will this work? can i shift bits in a 40 bit variable?
quest two:

i need to load this 40 bits onto 5 bytes that will be shifted out to the grid drivers:
Code:
grid1 var byte
grid2 var byte
grid3 var byte
grid4 var byte
grid5 var byte

shiftout portd.0, portd.1, msb[grid1\8, grid2\8, grid3\8, grid4\8, grid5\8]
how do i load the bits in grid[40] onto grid1, grid2, grid3, grid4, grid5?
in short, what is the easiest way to do a 40 bit scan, and then load it onto the 5 bytes?
im putting a lot of effort on this code project because i just snagged 16 of this vfd displays at a repo/surplus auction for $5. (they are inside some omni 490 credit card machines). so its worth it. thanks for reading