Started studying this book...Please someone explain this, thanks

"
Also note that we must be able to get each character back at least seven times on successive raster scans, and must be able to do this sixty times over for each second of display time.

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hi d,
It suggests that the characters are say 7*5 dots per character, in the character generator memory.
So to show every vertical dot pixel the character it is scanned 7 times in sequence. [top to bottom pixel]
The 60 times per second is the refresh rate for the characters on the screen..
Do you follow OK.?
E

 

yeah, thanks