metal shield

[Motormouth]

EM interference can be significant in some cases.   The FCC was particularly crazy about this in the 80's with so many computers and gaming systems coming out.   It was unclear what effect they would have like television or radio inference etc.  you also have to remember we were still using 12v and 5v lines had the "potential" (in this case both meanings) to radiate. and since the computer has signals of 10s of kilohertz to megahertz frequencies which are in the the radio/and TV bands and other communication bands of the era.  In the A500 the filter choke and the floppy cable are particular noisy according to my field meter.  

In an unrelated topic
@Tellurium,  Just curious why Tellurium, do you like the smell of onions?  Eventhough it is used in many things, tellurium is not the element most people think of.....

[Motormouth]

But wasn't the A1000 the only plastic Amiga to ship without metal RF shielding? What RF sheilding are you referring to on the A1000?

I wonder if the regulation was introduced post-1985...?

At least in the US  The regulations were pre 85.  Even the early system like the Atari VCS and Atari 800s had to meet specifications.  Particularly in the VHF and UHF bands ie 30 Mhz to 3Ghz (if my memory is correct) and the public radio air wave bands.

This of course only applies to the US.  Other countries has their own regulations, sometimes very stringent, sometimes non-existent
This is why the Commodore 128D  has a US version and an everywhere else version.  
The US version has a big heavy metal case.