Half of Sid's original money is $48/2 = $<<48/2=24>>24.
Sid has only $24 + $4 = $<<24+4=28>>28 left after his purchases.
He had $28 + $8 = $<<28+8=36>>36 before he spent $8 on snacks.
So, Sid spent $48 - $36 = $<<48-36=12>>12 on computer accessories.
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