Computer at home backing up sound system (5)

I believe the answer is:

nicam

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'up sound system' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'computer at home backing' is the wordplay.
'computer' becomes 'Mac' (Apple Mac computer).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'backing' says the letters should be written backwards.
'mac'+'in'='macin'
'macin' backwards is 'NICAM'.

Can you help me to learn more?

(Other definitions for nicam that I've seen before include "Digital video system" , "Digital TV system" .)

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