OT - Sinclair

At an antiques fair in London yesterday I bought a Sinclair Scientific Programmable calculator (circa 1975) for £5 (five English pounds). I thought that was a bargain for a RPN programmable calculator! It works perfectly and came with a mains charger and a complete set of program library cards (49) but no manual. Thought I would share this with you. Unfortunately I cannot supply a picture.



Does the machine have a 3-register stack? If it is, I had one and I recently sold it in my "grand liquidation" sae on eBay.

I remember buying the Sinclair programmable from Gallerie LaFayette (sp?) in paris in 1978. It was a nice toy. I never actually used it to calculate since I was using an HP-67 then.


Edited: 9 Apr 2006, 11:10 a.m.


You'll find many manuals (included many Sinclair calcs) here:


Please post more info about the calc...



You're right Stefano!
Let's all thank Katie for them...



Katie hasdone a wonderful job collecting these manuals!

Hat off for her!



Thanks for the information about the manuals when I get time I will download the right one and have a play. If anyone wants to see a picture I could email one to them.




for a photo


Thanks for the site. The picture shown is exactly the same as mine. The list taken from the site seems to be a good description
RPN Scientific Programmable
*2 level stack
*Tactile keyboard but not debounced as well as an HP, old TI, or Corvus
*1 memory, 25 program lines
*Made in Jolly Old England in 1975
*This is one odd beast:
-results are usually (but not always) in scientific notation
-trig is in radians only
-It has only 3 trig functions: Sin, Cos, & ARC tan.
-The enter key is a shifted function
-Constants entered into a program must be whole numbers.
*On the good side:
-The + and - keys work as enter for normal operation so that pesky shifted enter was only for programs.

heh, I have a lot of those in my collection as well. Nice photos.


Completely selfish question, Chris: which antiques fair?

Why do I ask? Well, I'd long ago given up looking for interesting old calcs at fairs and markets, partly for the same reason I don't look in charity shops for them: electrical equipment is a legal nightmare for second-hand shops and markets, because of safety regulations in the UK when sold to consumers. These regulations don't affect direct private sales, but do affect traders, which is why I'd assumed markets, fairs and second-hand shops aren't a good source of old calcs any more.

Your find suggests that I'm mistaken, but I'd like to find out what (if anything) is special about the fair you attended.




It was an antiques and collectors fair in Enfield, nothing special, I go there normally to look for old sliderules. The lady who sold it to me said that the calculator was her late husbands and she found it when clearing out his desk draws at home.

I guess I was just lucky!



electrical equipment is a legal nightmare for second-hand shops and markets, because of safety regulations in the UK when sold to consumers

As an American, I find this a bit baffling. Can you explain?


We have a similar regime here in Australia. I've never read the chapter and verse but I can give you the gist.

The principle being upheld is that consumers need to be certain that electrical products will not harm them. If they are harmed, they may need some form of legal redress. Caveat emptor cannot apply since the "average" consumer is not considered qualified to assess whether an appliance is "faulty" and therefore capable of causing harm.

In Australia it is illegal to sell an item that draws energy from the power grid if that item has not been certified to comply with applicable standards which make it safe. There must be some mumbo-jumbo in this law that voids compliance on re-sale after use (i.e. when the item attains second-hand status).

It is possible to re-certify a second-hand item. Once this task is complete, a compliance sticker is attached. The re-certification expires after a period of time (which I think is 6 months). Thus a second-hand item that does not sell must be regularly re-certified.

For most second-hand vendors (thrift shops, fund-raising fetes and the like), the cost and hassle turns most such items into a liability.

On a personal note, my mother (in her 70's) "works" at a Salvation Army thrift shop. They regularly fill a dumpster with donated appliances that, by policy, they will not sell. She sometimes intercepts them and brings them home for eldest son to approve.

She has yet to find me an HP calculator (although she is armed with several photographs). I did select a microwave oven, which appeared to be NIB, complete with manual, as a suitable replacement for our old clunker. This, it turned out, was a perfect illustration of why the compliance regulations exist.

I unsealed the box and inspected the packaging. It was clear at that point that the oven was not the one that had shipped in that box. However this oven was clean with a little sign of wear on the controls. The power cord was in very good condition. I plugged it in and as a test, programmed it to heat a glass of water. The interior light came on, the fan came on and the carousel rotated... for about 10 seconds.

From within the housing came a bang and the characteristic blue flash a high-voltage arc. I hit the wall switch just as the circuit breaker in our fuse box blew.

I speculate that this was the very reason its previous owner had replaced it with the appliance that actually came in the box this one was sealed in. I cut the power cord off and gave the oven to our municipal disposal service.

I will leave you to reflect on just why the previous owner thought this was a suitable donation to the Salvation Army.


Basically, what Cameron said.

Our local charity shops won't take electrical items, because of the burden of having to stand behind their safety when sold to consumers.

We take ours to a local recycling centre, where there is always a pile of freshly-dropped-off computers, toasters, microwaves, TVs and hair dryers.



Further to my last answer the calculator is battery operated. It did come with a mains unit but it did not have a plug on it. I would imagine the lady who sold me the calculator would not have done so if she knew the implications that are being suggested here. Are there any legal implications if the calculator is battery only.

Also what rules apply when selling on eBay?



This all seems so utterly insane to me. People kill themselves from stupidity all the time. It's called natural selection.

Edited: 12 Apr 2006, 7:29 p.m.



I would never call selecting a Sinclair calculator natural!!!!

I do think that because I have bought a second hand electrical item the onus is on me to check it out before using it and assume that it has been my personal decision to plug it in.



This all seems so utterly insane to me. People kill themselves from stupidity all the time. It's called natural selection.

Maybe so, but if I were to be electrocuted by my new laptop, I still feel that the manufacturer screwed up and should be accountable to some extent. I don't think there's anything unreasonable about trying to provide consumers with a certain baseline level of safety.

The disagreements usually start about just where to draw the line. To me, the English/Australian rules seem silly, but only the bit about re-certification of second-hand devices. I also think the U.S. law that requires airbags in all new cars is silly. But then again, I'm from Holland, where laws are different again, and I'm sure non-Dutch people would find plenty of things about my country silly, too, like our generous social security system. :-)

ObCalc: I like the Sinclairs. Back when we all drooled over HPs, but could not afford them, a plain old $60 Sinclair Scientific rescued me from the slide rule. Thanks, Sir Clive! :-)

- Thomas


Yes--it's the second had recertification thing that boggles my mind.

I don't think it has anything at all to do with safety. I think it has to do with sales. In the same way that the German government taxes old cars off the road (in order to boost domestic sales of VW etc) the Aussies are forcing old phonographs, toasters, etc etc into the dump so that new ones can be sold.

BTW, I bought a 40 year old toaster for a quarter. It works perfectly. It ahas a simple timer--not some stupid thermostat thing that never works anyway. And it wasn't recertified. :-)


I'm inclined to your POV Bill. I'll resist the temptation to go on about mandatory (re)certification of portable power tools (including laptops and battery chargers) that are taken into a workplace.

Suffice it to say that many of us have done the short course, sat the exam and can now certify our own tools. I acknowledge that deaths in an unsafe workplace are unacceptable. I'm not convinced that this is the way to solve that problem though.

I moved from the biological sciences to computer science after a brief encounter with Sir Clive's Z80-powered "PC" sometime around 1980. I only vaguely recall his calculators though.



ObDisclaimer; I am not a lawyer, and this is not legal advice.

I think battery-only is fine, simply because it's pretty hard to get a lethal discharge from one, or for a defective one to start a fire, but I wouldn't swear to it. There are probably a metric boatload of regulations we're generally unaware of, associated with stuff like mains-powered gear, gas appliances, tools, and suchlike. I imagine, for example, that since it's generally illegal to sell knives or solvents to anyone under 16 here, anyone who does that (even, perhaps, in a private sale) is breaking the law. Likewise for booze (18+ only) or cigarettes (16+ only), or GTA: Vice City (18+ only).

The rules for eBay are no different than anywhere else -- it's the nature of the sale (and the relative jurisdictions, for trans-border sales) that matter. So if you're a trader, and the electrical goods malarkey would apply to your sales, then they apply even when you sell online, eBay or otherwise.

In the UK, we also have distance selling regulations that require businesses to offer a mandatory cooling-off refund/return period,
which I think must be at least seven days. All the "no refunds" stuff you see on some eBay sales are notionally ineffective here, since the buyer has a right of return for goods purchased at a distance -- eBay, over the phone, via SMS text message, whatever.
(It doesn't apply to private sales, though, as far as I know.)


"I will leave you to reflect on just why the previous owner thought this was a suitable donation to the Salvation Army."

My wife and i have helped at "thrift stores" such as those run by the Salvation Army, by Hospice, by Goodwill, and others. The main reason people drop off stuff like that as a "donation" is that it is easier than taking it to the disposal site or is less expensive than paying for disposal. On top of that many of these people even ask for receipts so that they can declare the "donation" as a deduction for income tax purposes. Thus, the "thrift stores" receive bags and bags of moldy clothing, mattresses which have been left out in the rain, burned-out TV's and so on, and their only alternative is to haul it to a disposal site. It's not a perfect world that we live in!

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