The UK did not have emissions regulations at the time, and the most popular computer of the early 80s in the UK, the Acorn BBC Micro, had no shielding whatsoever.
Acorn wanted to break into the US market, and so they had to redesign the computer with a massive metal box inside the outer plastic case.
Their attempt to launch in the US was a huge failure, and most of those computers were shipped back to the UK and "unconverted" to be resold in their home market.
But they didn't remove the metal box. So Brits could always tell when they had an ex-US BBC Micro because it weighed twice as much and had a huge metal box inside it.
Seems strange no one came up with spraying the inside of the case with a metallic shielding layer of paint, as some later products eventually did.
Author of the OP here. The "spray" technique was known in the early 80s, if not earlier. It's mentioned in Michael Tomczyk's "Home Computer Wars":
> The solution came in several forms. One way was to embed ferrite balls in the plastic case. Another way was to spray the inside of the case with a metal coating. But the best way was to encase the offending electronics in a small metal box inside the case, which is what was done with the VIC-20. [0]
Why a metal box is the best way, he doesn't say and I don't know. My best guess is that it was more effective/reliable at passing the tests.
The fact that the Apple II met the new FCC requirements was a major competitive advantage for Apple, and there have been rumors over the years about how that happened. The higher emissions allowance was why you saw the big shift from monsters like the Atari 800 (heavy cast metal frame, aluminum or pot metal) and Commodore PET to lighter chassis like the Atari XL series and the Commodore VIC-20 and C64.
The old FCC Standards kneecapped Atari. I think Atari would have had a much showing against Apple had they not had to have the heavy and expensive cast box inside every 400/800 and the increased cost for "smart" peripherals versus "dumb" slots. Those Atari machines are arguably more technically advanced and capable than the Apple II. The cost of FCC compliance drove up the price and hurt their market share.
I've always thought the whole Apple / aftermarket RF modulator trick was a bit underhanded.
I had an Atari 400 as the first computer I bought myself, which I upgraded to a “real” (if small) keyboard that replaced the membrane keyboard. I took it to college and used it with a printer and the Action! cartridge editor to write papers. (My printer was a carbon electrode arc printer that burned marks into regular paper, producing a soft brownish print.)
And I'm reading this article while sitting at an EMC/EMI test facility monitoring the test for one of my products. Certainly an interesting, and somewhat on-topic, read.
usb mouse discovered
Joe DeCur, primary architect of the Atari SIO bus, was involved in the design of USB. Some of his Atari-era notebooks helped kill a patent troll who was trying to extract rents from everybody using USB.
The UK did not have emissions regulations at the time, and the most popular computer of the early 80s in the UK, the Acorn BBC Micro, had no shielding whatsoever.
Acorn wanted to break into the US market, and so they had to redesign the computer with a massive metal box inside the outer plastic case.
Their attempt to launch in the US was a huge failure, and most of those computers were shipped back to the UK and "unconverted" to be resold in their home market.
But they didn't remove the metal box. So Brits could always tell when they had an ex-US BBC Micro because it weighed twice as much and had a huge metal box inside it.
Seems strange no one came up with spraying the inside of the case with a metallic shielding layer of paint, as some later products eventually did.
Author of the OP here. The "spray" technique was known in the early 80s, if not earlier. It's mentioned in Michael Tomczyk's "Home Computer Wars":
> The solution came in several forms. One way was to embed ferrite balls in the plastic case. Another way was to spray the inside of the case with a metal coating. But the best way was to encase the offending electronics in a small metal box inside the case, which is what was done with the VIC-20. [0]
Why a metal box is the best way, he doesn't say and I don't know. My best guess is that it was more effective/reliable at passing the tests.
[0]: https://archive.org/details/the-home-computer-wars/page/205/...
The fact that the Apple II met the new FCC requirements was a major competitive advantage for Apple, and there have been rumors over the years about how that happened. The higher emissions allowance was why you saw the big shift from monsters like the Atari 800 (heavy cast metal frame, aluminum or pot metal) and Commodore PET to lighter chassis like the Atari XL series and the Commodore VIC-20 and C64.
The old FCC Standards kneecapped Atari. I think Atari would have had a much showing against Apple had they not had to have the heavy and expensive cast box inside every 400/800 and the increased cost for "smart" peripherals versus "dumb" slots. Those Atari machines are arguably more technically advanced and capable than the Apple II. The cost of FCC compliance drove up the price and hurt their market share.
I've always thought the whole Apple / aftermarket RF modulator trick was a bit underhanded.
I had an Atari 400 as the first computer I bought myself, which I upgraded to a “real” (if small) keyboard that replaced the membrane keyboard. I took it to college and used it with a printer and the Action! cartridge editor to write papers. (My printer was a carbon electrode arc printer that burned marks into regular paper, producing a soft brownish print.)
And I'm reading this article while sitting at an EMC/EMI test facility monitoring the test for one of my products. Certainly an interesting, and somewhat on-topic, read.
usb mouse discovered
Joe DeCur, primary architect of the Atari SIO bus, was involved in the design of USB. Some of his Atari-era notebooks helped kill a patent troll who was trying to extract rents from everybody using USB.