question regarding VGA tutor in "Rapid Prototyping of Digital Systems"

[Altera_Forum]

Hi, 

I'm doing the VGA tutorial from the "Rapid Prototyping of Digital Systems-SOPC" book. In page 202 of the book, in the CHAR ROM chapter, there's a line: rom_mux_output <= rom_data (CONV_INTEGER( not font_col( 2 downto 0 ))) );   I would be very happy if someone could explain this line to me... The rom_mux should choose 1 bit from 8 bit word it has in the CHAR ROM memory. the font_col says which line it chooses in order to show the letter 'A' (for example) on the screen. (the letter A is made of eight 8-bit words, each word is 8 pixels which forms the letter A)    Why conv_integer is needed? why is there a NOT function before the font_col?   Any help would be very appreciated... Thank you! Roy  

[Altera_Forum]

ok, found the answer from some code on the net:-- Mux to pick off correct rom data bit from 8-bit word-- This is needed because while the column count goes from left to right on screen,-- the same pixels are indexed from right to left in rom_data. rom_mux_output

[Altera_Forum]

-- Mux to pick off correct rom data bit from 8-bit word-- This is needed because while the column count goes from left to right on screen,-- the same pixels are indexed from right to left in rom_data. rom_mux_output

[Altera_Forum]

I don't know why, but the lines which I copy-paste get all messed up. sorry for that.Check out this link. it's in there:http://www.ece.ualberta.ca/~elliott/ee552/projects/2000f/cdu/cdu/probedisplay.vhd