Nerd Killed by Computer Returns as Demon to Terrorize High School

by Demi
(USA)

I am trying desperately to find an 80's film about a demon terrorizing a high school and systematically killing all the girls. What little I recall is as follows:

1) The aforementioned nerd is killed by his computer and turns into some sort of computerized zombie (his head is a monitor and he's got a disc drive in his back).

2) The demon marks his kills in a yearbook with a long bloody fingernail.

3) A zombie is killed by a flag to the head and impaled into a chalkboard.

4) The resolution involves a basketball game.

Thanks.