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Current Radio Rules Mean Sinclair ZX Spectrum Wouldn't Fly Today
First time accepted submitter wisewellies writes "Ben clearly has way too much spare time on his hands, but he decided to see just how well an antiquated ZX Spectrum would hold up to modern EMC requirements. His blog is a good read if you're looking for something to do while pretending to work! From the blog: 'This year is the 30th anniversary of one of my favourite inventions of all time, the Sinclair ZX Spectrum. A few weeks ago, I finally bought one: a non-working one on eBay that I nursed back to health. Fortunately there was very little wrong with it. Unfortunately it's a 16K model, and a fairly early one at that, which won't run much software in its native state. This probably accounts for its unusually pristine condition. We took half an hour in the chamber to perform an approximate series of EN55022 measurements, to check its radiated emissions against today's standard. The question is, what have we learned as an industry since 1982?'"
Sorry, I couldn't help myself .....
Hey Hey 16k
upgrade the motherboard.
"I bless every day that I continue to live, for every day is pure profit."
I remember if neighbor within ~100m distance played with famicom we could watch on TV on certain channels and how my grandpa got pissed when he couldnt watch TV...
EMI, Electro-Magnetic Interference
"It’s not just a failure; it’s an abject one" Really? Now I admit the situation could be a ALOT worse with the accessories and cables, and until you've ran the test you don't know. But it's only about 6dB above the line, I've seen a lot worse problems [try 20dB!]. There is a good chance this would be a relatively easy fix when you start looking at the problem.
A ferrite bead on the power supply cable would probably fix the "bad power" supply if indeed that's what it is. And some judicious copper taping would likely fix the other problems. Worse case you do a board spin and add ferrite beads to the I/O and possibly move suspect traces into internal layers. Worse WORSE case you change the clocking to use spread spectrum which would likely not require any changes except in the clocking circuits. None of those would prevent a "modern" version of the product from going to market.. And a good engineer could probably implement them in less than 6 weeks in a production environment...
Plus it doesn't even manner, if you were going to bring a sinclair back to market it would draw about 20mA, run on USB power and be completely implemented on a single chip.... Because it has roughly the same processing power as a PIC uC.
The ZX didn't fly back in the day either. /rimshot
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Yes.. but what about the zx81/TS1000?
I have a ZX Spectrum in the loft I often see when I go up there. As far as RFI is concerned our regulations back then were non-existent. I once saw a BBC Micro for the German market, it was encased in metal and built like a tank. The ones on the UK market were plastic and caused havoc with my Amateur Radio gear until I quietened it a fair bit by coating the inside of the case with graphite spray and grounding it. TV's were another problem as they were susceptible to interference from Amateur radio transmissions operating within the legal limits and specifications and we had inspectors who audited our stations for compliance. It was all down to the manufacturers saving may be a penny or 2 by using a cheaper front-end transistor for TV's sold into the UK.
The original Atari 800s were built to the old emissions rules, and had some horribly slow serial I/O as a result.
FCC class C was specifically relaxed to allow PCs to get to market in the early 1980s.
I wrote my first real program on a Sinclair. It was for TV troubleshooting and it took you down to the section. Storage was a cassette tape and the output was composite video for black & white TV.
Then I bought the memory expansion, took it to work and made a program for it to do cost estimate calculations. It was the 2nd computer anywhere in the company. I got promoted from cost estimating to Systems Administrator all in one go. I stayed with that company almost 30 years, then I left to start my own software company.
A few years ago I was telling that story to a client. He pulled a mint condition Sinclair -- still in the original box -- out of his desk and gave it to me. He said it bought it to learn computers and never used it. It was like giving me the keys to my first car.
Unfortunately it's a 16K model, and a fairly early one at that, which won't run much software
Hey! I was still supporting the 16k version with a game released in NINETY-two.
Anyone who held a radio near a Spectrum was well aware of this.
I seem to remember some people even used it as a way to play better music than the internal speaker could produce by finding the notes that different code loops would produce?
The Spectrum made audible noises when running. Not via the speaker AFAICT, actual noise made by the chips themselves. I've never head that with other devices.
Nowadays, there are emulators and roms for just about every piece of older hardware, including the "Speccy". Here's a quickie google search link: http://www.google.com/search?hl=en&gl=US&ie=UTF-8&source=android-browser&q=zx+spectrum+emulator
Yeah, where are the days if a motorcycle passed ones house, that the TV reception was jammed?
you guys really waste memory. 16KB? way too much ... real programmers used the ZX80 with its whopping 1KB of ram. If you didn't mind really short messages you fit versions of games from the People's Computer Company into it. For a measely $199 in the later 1970's
The original TRS-80 was a wideband RF jammer. Cheap PCB design, plastic (unshielded) case, lots of ribbon cable external interconnects operating at megahertz frequencies.
One of the better ways to see whether the machine was frozen or just processing a long-running (but productive) internal loop was turn on an AM radio in the same room. Within about 3 feet, the RF noise would override all but the strongest stations and allow you to monitor the CPU's execution by the hums and burbles of the RF noise.
It's why the original TRS-80 became the Model I, rapidly superseded by the all-in-one Model III (with lots of internal shielding).
Welcome to the Panopticon. Used to be a prison, now it's your home.
would interfere with sound from the radio station, I discovered as a kid. And just when I had thought the Spectrum couldn't be any cooler...!
Here's the actual blog instead of some stupid Register article: http://focusritedevelopmentteam.wordpress.com/
Don't store it in the loft. The large fluctuations in temperature aren't good for it and summer weather has probably already dried out its electrolytic capacitors.
The good news is that it can probably be brought back to life fairly easily. However, don't just plug it in without making some basic checks first or there's a good chance the lower RAM ICs will die.
Seek advice on the forums at www.worldofspectrum.org if you want more information.
That's today. I live within walking distance of downtown in the largest city of my state. It's very frequent that a vehicle will pass by and cause my DTV to drop out for a couple seconds. That's with a UHF antenna and amplifier. Not every vehicle, not every day, but it's often enough that I watch low def analog cable in preference to OTA free HD TV when a program is available on both.
Give me Classic Slashdot or give me death!
>The question is, what have we learned as an industry since 1982?
Quite a bit.
I have three books on electromagnetic compatibility. The most recent, Electromagnetic Compatibility Engineering (2009), is comprehensive and thick enough to stun an ox.
I once made a QBasic program named "NOISE.BAS" on a 386 computer.
When ran, it made the radio which was playing, produce noise for 7 seconds.
All the program contained was:
SLEEP 7
The TVs were made that way on purpose, to allow the TV police to easily sniff the sets' internal oscillators to track them down for taxes, right? (I'm American.)
The determined Real Programmer can write Fortran programs in any language.
I'm kind of surprised it hasn't been done yet. Same for the generation after like Amiga and Atari ST.
We're really lucky that the FCC clamped down on RF emissions from electronics. Otherwise, we'd all be looking at big electromagnetic compatibility charts before buying anything, trying to find combinations known to work well together. Offices would need RF spectrum analyzers to figure out who brought in something that was messing up other gear. I mentioned in another post that you couldn't operate a Milton Bradley Big Trak and an TRS-80 near each other. The other side of stopping RF emissions is that the shielding makes electronics much less sensitive to RF interference.
The development of really good RF noise management technology made modern cell phones possible. The concept of a handheld device with four radios (GSM, WiFi, GPS, and Bluetooth), all operating simultaneously within a few inches of each other, was totally beyond the RF technology of a generation ago. Two generations ago, it was so bad that marine radio stations had miles of separation between the receivers and the transmitters.
I tried a spectrum in a shop. Every time I pressed a key on the keyboard the TV monitor lost its vertical sync.
http://michaelsmith.id.au
Last night we found out that my Mattel Electronics "Las Vegas" pinball from 1977 broadcasts its sounds across 96.1Mhz to 107.9Mhz! We started hearing the game on the boom box 30 feet across the room!
I've always wondered how mobile phones are allowed to exist when they interfere with anything that has speakers. I remember circa 1999 when I started noticing this strange d d d...d d d coming from computer speakers at work. We eventually realised it was that someone had a mobile phone in the room. Our VT terminals once completely freaked out when someone made a call and ever since I've wondered how this is allowed.
I remember hearing that the Vic 20 was delayed because it needed to have shielding added, and I've never noticed interference from any device apart from phones. Even new ones cause terrible interference on radios. My Dad has a Blackberry and he can't put it in the small holder near his radio as it constantly makes noises on it.
Can anyone explain any of this?
New EMI rules are required to keep modern offenders in check. The old ZX is a weak example.
That if marketed properly we can bilk the public out of their money every year with shiny new objects that really are not much different than last years shiny object.
---- Booth was a patriot ----
Flying PCs come after flying cars, dammit.
You need a better antenna, probably a much better antenna, and locate it higher. If you cannot do that, suboptimal antenna placement alone can cause all sorts of issues. I have an almost 2m rig in the attic, at a height of over 10m, and I'm on a hill. I get signal strengths no lower than 90% from about 25 channels, even 3 from a city 75 km away at a 40 degree angle from my primaries. Oh, and there's an entire suite of skyscrapers in between me and my primaries, which are roughly 40 km away. I tried the amplified rabbit ears, and other indoor antennas, and had extremely poor reception on the handful of channels I could receive.
The cesspool just got a check and balance.
I used to SAVE programs over the CB airwaves for other people to LOAD, and never noticed any great problems with the Speccy interfering with my CB :)
(I put a socket on the back of my CB fist-mic - this was at the height of the CB craze after UK legalisation in Nov 1981 - so that I could plug in other mics, or line-level audio via a resistive dropper. I found that hooking it up to the Speccy I could SAVE over the air with a nice clear modulation (CB is FM in the UK - 27MHz) with enough quality that other people were able to hook up their CBs to the line-in socket of their Speccy and LOAD what I was sending to them. It worked just fine!)