Do you know if there's any of these calculators still around and available to purchase? I've always wanted to get my hands on a curta but One of these would be awesome too.
It looks like the Sinclair Scientific sells on eBay for about $45, but there aren't any for sale right now. The Curta, on the other hand, goes for over $1000, so not exactly an impulse purchase.
The price of Curtas seems to have gone up over the past 18 months. eBay has plenty of listings for Curta I and IIs, but you'd have to shell out more than US$1000 for one, unless the unit was in bad condition.
What first piqued my interest in them was a watch and clock show in my town. I remember really thinking they were marvelous engineering, but I also remember that number of $1000 as an average for a working one.
However it's kinda iffy buying one that you can't actually test first. It's been too long since I've purchased anything on eBay so I don't know what the return policies are.
The guy at the show mentioned "always test the _one_ slider. Those go first"
eBay leaves the return policies to the individual sellers, so some sellers absorb the cost of returns, some require you to pay postage, and some don't accept returns at all. Naturally some of this probably gets absorbed into the listing price.
@kens: Thanks, long time follower of your work. Are you familiar with the inner workings of the HP Voyager (11-C, 12-C, ..., 16-C) series, and if so, is a teardown/analysis of these something that you'd be wanting to do?
Yes, I was curious and a bit skeptical when I heard that they fit these scientific operations into 320 instructions. That's what motivated me to look at the chip in detail, to see how they did it.
Do you have any good suggested reading material on how to look at chips in the way that you mean? I have no knowledge when it comes to this type of hardware.
You might be surprised to learn that the calculator chip cannot perform multiplication natively. There's no floating point unit to multiply two numbers. Instead, multiplication is performed through repeated addition, digit by digit.
I believe all the ultra-cheap 4-function calculator ASICs do this or something similar; the speed is not at all important, but die area and resulting price are.
when i read ideas like this I'm not sure what they mean
none of the early microprocessors had multiply instructions, but you can carry out a binary multiply using repeated shift+add, and if you don't have a shift you can add a number to itself and that's a shift... so all you are doing is adding but it's not the naive idea of adding a number over and over to simulate multiplication
or do they mean digit by digit and they are doing BCD multiplies? again, not that many adds are being performed so it's not a performance nightmare.
youngbloods don't realize how rarely a C programmer would invoke a multiply (or really need to) (and NEVER inside a loop) even a decade after these early calculators
That is so classic Sinclair. Barely working enough to be useful ("three decimal places of accuracy at best", "sin 1 takes about 7.5 seconds", and constants like pi and e are written on the case instead of fitting in ROM), but useful nonetheless, and dirt cheap.
Sinclair products were almost comical in how ingeniously their engineers shaved off any pennies they could. In the ZX81, the video circuit is a bizarre and extremely interesting contraption that abuses the Z80's DRAM refresh circuitry, and on the mechanical side only two screws hold down the PCB to the case, despite there being many more intended screw holes in both PCB and case (someone must have figured out that hey, it still holds in place with two).
I have marveled a lot at what the engineers came up with, and cursed at it just as much.
For the ZX81's ingenious video circuit and sleek case, you get a device with chips that get dangerously (literally painfully) hot, and most CPU time used for drawing the screen--without the ability to set individual pixels in any way. The keyboard "cable" plugged into the PCB is just an extension of the paper-like foil that makes up the terrible, terrible keyboard, and that can easily self-destruct when disassembling your ZX81: The foil does not like any amount of bending, including the bending when you fold the case open.
I could go on an on about how clever Sinclair's engineering was to barely stay past the line of what makes a working product so brilliantly.
It's a fantastic example of 'good enough', because the alternative was doing this all by hand or using mechanical tools which - while sometimes quite fast - were error prone especially for long and repetitive calculations.
An Olivetti electronic/mechanical calculator for instance took up half your desk, was horribly slow and consumed a ton of power. No way that you would ever take it with you and working with the beast would require a serious investment in time, they weren't cheap either.
These little calculators were complete game changers. The model in the article was one of my prized possessions, there simply was no alternative that I could have afforded.
> Sinclair products were almost comical in how ingeniously their engineers shaved off any pennies they could.
Yes, that was their rule from day 1.
My favorite: in the early days, Sinclair designed a very cheap transistor radio -- so cheap that it didn't even have a speaker, just an earphone (mono, one ear). Sinclair noticed that the available earphone jacks had a built-in switch that was intended to disconnect the speaker when the earphone plug was inserted. Since there was no speaker, this switch was repurposed to serve as the on-off switch for the unit -- plug in the earphone and it's on, pull it out and it's off. That saved both the cost of a separate switch and the space it would have taken up.
I believe this hack required manually bending the contacts on the jack switch to turn it from NC to NO.
>without the ability to set individual pixels in any way
You could and I did. ALas it involved rewritting the screen driver and drawing a diagnol across the screen would take over a minute and all the CPU, now if you turned the display off (ala fast mode polling) then you could improve upon that.
One stand-out thing that puts perspective upon the ZX81 was as you moot - the price for what you did get at the time, a time in which you could pay more for a pack of 8" floppy discs or a keyboard.
It's ironic how you point out the short-cuts - something Amstrad had more a reputation for. With that I'd tend to agree that the case design of the ZX81 was a work of art in design.
How exactly did you set individual pixels on an unmodified ZX81 without extra hardware? As far as I know, that’s not possible, even when rewriting the screen driver. The font came from ROM, and while you could do things like switch where in ROM the font starts with every scan line, that only gave you “Pseudo HiRes” capabilities where not every combination was possible, see e.g. https://perfectlynormalsite.com/zxhires.html
Was few ways and sure changing the ROM, but with RAMpack you had the space to redo the interupt controlling the display and probebly best demoed with https://www.youtube.com/watch?v=EjA-qlDv5Xw Though for this they just pointed the character map to some RAM to do UDG's for the effect.
I'd add though to do true resolution you kinda had to update things a lot of times and why the code I did at the time was in effect doing 8x8 more work - hence was about 2 mins just to draw vertical line. Just not enough processing power to ever be of use. Though the remap the interupt into RAM and char set was good and lost no performance and indeed you would expect it to be slightly faster with the old RAM vs ROM access times, but kinda mute back in those days of when RAM was faster than the CPU's.
Yeah but that was my point, you at the very least need a RAMpack, and often one with modifications. It is not just for having the space to have the custom display code, you actually need the RAMpack for the data lines on the bus. Without a RAMpack, the ULA would fetch the character rows from ROM and ROM only, no way around it. And not all RAMpacks worked for this, a lot (most?) had to be further modified in hardware.
The original device without RAMpack did not let you set individual pixels at all (and even with a suitable/modified RAMpack it was a giant hack obviously).
I got curious whether Manic Miner actually found a way to do actual hires without added hardware, but this answer claims it's also (just) pseudo hires... although a rather impressive example of it, I wasn't sure from the video you posted:
https://retrocomputing.stackexchange.com/questions/6134/how-...
Nowadays, that’s two more than a product with cutthroat pricing should have. Engineering tolerances, even at low cost, are good enough to clamp the PCB in place.
Or their manufacturing was so imprecise that they had to make more than two holes to (most of the time) get at least two that were in the right-enough place and where the screw would actually “grip” the plastic.
I expect, though, that the first batch used all holes and that this was a matter of using excess inventory with too many holes after realizing that they could do with fewer ones.
Interesting with the imprecise manufacturing, haven't thought about it like that (and obviously don't know anything about the mechanical part of manufacturing).
I'm better at judging the electronics/computer design, and there it's obvious to me that they went out of their way to stay cheap.
Are you Munroe Live on Youtube? It's a channel where they disassemble and review the internals of EVs. Any time he comes across a screw (threaded fastener), which happens all the time, he turns red and politely hints how the designers could have done a much better job.
I think so, cheap knockoff products nowadays usually use cheap parts and put them together in cheap but obvious ways. If you dive into Sinclair engineering, it’s contrived and interesting.
> Scientific calculators usually provide constants such as e and p but there was no space in the ROM for these constants. The Sinclair Scientific used the brilliant solution of printing the constants on the calculator's case
I love this so much. I sometimes wonder what single-purpose electronic devices could be replaced with a piece of paper or a purely mechanical instrument.
Could one make a countdown timer with no spring, just having a ball fall down a kind of maze for instance?
My Dad had one of those calculators he built from a kit.
I remember it had a great bug if you divided by 0. It would go mad for a moment then start counting very quickly on the screen.
My time spent with the calculator was doing that, and trying to make sums which came up with rude words when held upside down! (I was too young to appreciate the trig features!)
The old man build lots of Sinclair kits including the watch, and it was the ZX80 that got me into computing. That took a long time for him to make it work as the PCB had a cracked track.
Happy days and thanks for all the good memories Mr Sinclair (as we always used to call him in our house!).
I love these articles. At the end there is this bit:
"The Sinclair Scientific came out in 1974 and was the first single-chip scientific calculator (if you ignore the display driver chips). It was stylishly compact, just 3/4 inch thick. It originally sold for the price of $119.95 or £49.95 and by the end of the year was available as a kit for the amazingly low price of £9.95.
Unfortunately, as calculator prices collapsed, so did Sinclair Radionics' profits, and the company was broken up in 1979 after heavy losses."
In a nutshell that is both the genius and the curse of Clive Sinclair, he moved markets with complete disregard for the consequences effectively out-competing himself and the would move on to some other field. I always thought that was the best kind of inventor, the one that doesn't care about milking the cows they field, but that democratizes a field to the point that they themselves become obsolete.
Imagine if he had not shown that you can have < $20 calculators or < $100 computers, that would have had major impact on so many people, their careers and the solutions they built that the world would probably look different today.
No disrespect to Sinclair, but this reads like Great Man history to me.
Computers aren't (relatively) cheap today because Sinclair gave people the idea they could be cheap. They're cheap because of the incremental efforts of thousand of people from research scientists to manufacturing engineers. For instance, the cheaper version of the calculator was built around Texas Instrument's TMS1802NC.
If Sinclair didn't seize on the opportunity to use the TMS1802NC to reduce costs, then one of his competitors would have eventually done it.
You see it happening today. The iPhone launched for $658.38 (inflation adjusted), but today you can buy the vastly superior iPhone SE for half that price. You can go cheaper still if you're willing to go down the Android route.
We didn't need Sinclair to show us that was possible.
I think you misunderstand. The Sinclair model was to design something as cheaply as possible using insane engineering workarounds to shave every last possible penny off the price. Then to package it with better-than-average industrial design and sell it through a marketing blitzkrieg.
Sinclair came to give a talk at our college and explained this was a deliberate and calculate strategy. He sketched a graph showing that maximum profit for his way of working was around a margin of 50%. Unlike most engineers, he was thinking in business terms throughout - while also appreciating the engineering challenges.
It was an excellent strategy for his market, which was mostly nerds and engineers who appreciated low cost access to advanced tech.
Compare the HP and TI calculators with the Sinclair models for context.
There was an engineering-led tradition at HP etc which produced leading edge no-compromise products, but they were sold at leading-edge no-compromise prices. The HP-65 cost the equivalent of >$4000 in modern money.
When you bought a Sinclair calculator you didn't just buy a plastic package with a TI chip inside. You bought the chance to feel a part of a British engineering tradition of cut corners and minimal solutions which nonetheless still sort-of-mostly worked.
You would read about the various hacks and cost saving tricks and think "That's really clever. How does that work, exactly? I wonder if I could that?"
That was the core of the Sinclair branding. It was the ethic that created the ZX series and gave developers and bedroom entrepreneurs a start. It was a scene, and it was the reason he was so influential when more conventional calculator companies - of which there were very many - weren't.
> When you bought a Sinclair calculator you didn't just buy a plastic package with a TI chip inside. You bought the chance to feel a part of a British engineering tradition of cut corners and minimal solutions which nonetheless still sort-of-mostly worked.
Americans: You have the 'nerd' and the 'hacker', but we have the 'boffin' and the 'bodger'. I'm probably the latter.
> If Sinclair didn't seize on the opportunity to use the TMS1802NC to reduce costs, then one of his competitors would have eventually done it.
You are missing the point entirely: Sinclair did seize on the opportunity and nobody else did, and likely would not have.
Sinclair did this quite purposefully when in fact if he had been more greedy he could have chosen a different path. And the fact that he did this repeatedly is proof that this was not an accident. So yes, we did need Sinclair to show us that was possible.
> We didn't need Sinclair to show us that was possible.
No. Nigel Searle, Sinclair's programming and math whiz, actually did it.
Steve Wozniak actually did it.
Archimedes actually did it.
Etc.
I'm not a big fan of Great Person narratives. And yet it's also true that some minds seem adept at finding shortcuts to previously seemingly intractable problems.
How many persons have the actual willingness to defy conventional wisdom, forging progress faster than the mortality rate of the old guard?
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