Current Radio Rules Mean Sinclair ZX Spectrum Wouldn't Fly Today 64
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?'"
Hey Hey 16K (Score:2, Funny)
Sorry, I couldn't help myself .....
Hey Hey 16k [b3ta.com]
Obvious Solution (Score:3)
upgrade the motherboard. [technabob.com]
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What a retarded article. So, some one wastes their time removing the innards off a dead ZX spectrum, cram it with modern day hardware running an emulator, and now somehow that's supposed to be a ZX spectrum.
Retards. This isn't even theseus' ship.
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EMC - Electro-Magnetic Compatibility
Abject Failure? (Score:5, Insightful)
"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.
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4Layer? It was probably 2. But a worse case scenario would've been to make it more. Remember we're talking today.. Today an 8-layer board is nearly as cheap as a 2-layer board and if it meant having a legal product it would've been done.
let's be honest here... (Score:4, Funny)
Re:let's be honest here... (Score:4, Funny)
The ZX didn't fly back in the day either. /rimshot
That depends on how hard you threw it.
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They went to the Moon with less!
zx81? (Score:2)
RE: ZX Spectrum radiation (Score:5, Interesting)
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Yeah, where are the days if a motorcycle passed ones house, that the TV reception was jammed?
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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.
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Happy Birthday Sinclair (Score:5, Interesting)
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.
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Likewise. I was in business school 30 years ago, and a professor gave us an exercise to optimize return on a marketing budget, subject to a set of equations and constraints. "Go to the computer center on campus - it's in the DECsystem 10 there. Log in and see what values of the variables - print versus radio versus TV versus billboard - gets you the best sales revenue." Trial and error to see where to spend my marketing budget? When I have a Timex Sinclair 1000 at home, including the memory expansion o
16k was good enough (Score:3)
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.
You could hear it (Score:2)
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.
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Nowadays, there are emulators and roms for just about every piece of older hardware, including the "Speccy".
There must be plenty of dead Speccys around, and a Raspberry Pi would fit inside the box nicely. Hooking up the Speccy keyboard to the Pi's I/O pins and knocking up a driver can't be rocket science, then you could...
...install a BBC Micro emulator on it and have a decent computer (ducks and runs for cover...!)
Aaah, we had proper platform loyalty wars back in the good old days - so much better than all this cissy modern Fanbois vs. Fandroids rubbish. Tim Cook and Eric Schmitt might talk up a storm but you
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1k less the memory used to hold the characters currently on the display. But you try and tell the people of today [youtube.com]...
The TRS-80 had this problem too (Score:5, Interesting)
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). [oldcomputers.net]
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The original TRS-80 was a wideband RF jammer
It sure was - I remember our Model I used to sit in a room upstairs in our house, directly under our TV antenna. You could tell whether my brother was playing Sea Dragon or Scarfman based on the interference on the TV.
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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.
Not only was the TRS-80 an RF noise generator, it was sensitive to other RF sources in the vicinity. It was noted at the time that a TRS-80 and a Milton Bradley Big Trak [wikipedia.org] would both crash if operated near each other.
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I remember I had to turn mine off if the family wanted to watch TV channel 12. We lived far enough out in a rural area that we had to use a nice big antenna. which only made things worse.
The cassette port was often used for sound output from games, but the very act of doing the timing for sound made it not much worse to just put an AM radio next to it. You kids and your Bluetooth headsets, we had REAL wireless audio back in the day!
It's true, pressing the SHIFT key... (Score:1)
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...!
Actual Link (Score:5, Informative)
Since 1982? (Score:2)
>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.
QBasic sleep (Score:3)
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
I'm not surprised (Score:2)
We're lucky the FCC clamped down (Score:5, Interesting)
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 [radiomarine.org] had miles of separation between the receivers and the transmitters.
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Not to mention the RF emissions would likely be able to used as a side channel to break crypto, which is much more common today than in the late 1970s.
http://syhw.posterous.com/two-amusing-side-channel-attacks [posterous.com]
Yeah I remember that (Score:2)
I tried a spectrum in a shop. Every time I pressed a key on the keyboard the TV monitor lost its vertical sync.
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You may both be thinking of the ZX80 or ZX81, which used this hack to drive the screen. The ZX Spectrum (released 1982) had proper display circuitry and did not suffer from this issue.
The ZX80's display hack was all a cheap way to get the data streamed out of RAM. To do this they placed the cpu's program counter(!) at the start of display memory, every time it tried to execute an instruction it would read a byte from memory - which was picked up to generate the display - but the data wasn't returned to the
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Yeah, the display hardware of the ZX81 was brilliant in its simplicity.
Not only did it use the program counter as the character point er for the display, but the I/R (interrupt and DRAM refresh) register pair was used as a pointer into the character ROM. These were output automatically by the processor directly after the fetch of the instruction.
And each line of the display was ended by a HALT instruction, so short lines did not need the full 32 bytes.
And, and, and... I loved that machine for its (albeit ju
Not just computers... (Score:1)
How are mobile phones legal then? (Score:1)
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,
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As the AC implies, that's not interference from bad or unshielded electronics in the mobile (or it shouldn't be).
An ideal mobile transmits only what it's supposed to, on the correct RF channels to communicate, and nothing else.
Like all devices there will be other emissions, but let's assume it's very well made and effectively perfect.
The sound on the speakers is because the speaker circuit is effectively an RF receiver, converting those high frequencies to audio. They actually demodulate the signal - uninte
What have we learned? (Score:2)
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.
Can't have been all that bad... (Score:1)
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 peo