 I have a new calculator. This is a Canon P2D financial accounting calculator dating from as far as I can tell about 1983. I picked this up in the junk shop for way too much money. I think this cost me nearly eight francs. It caught my eye because firstly it's a financial calculator as you can tell by the interesting buttons and secondly the rather neat printer mechanism which I'll demonstrate later. These machines were not intended as general purpose calculators. These are the direct descendants of the early hand-cranked mechanical calculators intended for summing large series of numbers for like stock-taking purposes. Originally you would enter the numbers you want to add and crank a mechanical handle and it would then use mechanical logic to actually do the addition. Later ones were electromechanical where you would use a traditional number pad but all the actual arithmetic was done with mechanical logic. This is a portable battery-powered electronic version of the same. I've always wanted one of these since I was a small child just because it's an interesting toy mainly the printer which is really cool so I was rather glad to see one. Of course immediately after I bought it I then discovered a much nicer one in the junk shop but let's just go with this one for simplicity. Here it is ready for use. It's hooked up to my bench power supply to avoid gobbling through batteries. It's propped up on a box of flux paste to try and make the LCD visible. These old-fashioned calculator displays are painful to video apologies for the low contrast and I'll just remove the lid to the printer compartment so you can see the printer in operation. So power on. So in operation it's pretty straightforward. It is an adding machine. You fundamentally use these buttons. The screen displays the current subtotal. To add a number you type in the number and then press plus or minus. It is not an infix calculator. So nine. That has printed nine plus to indicate we've incremented the total. Add a one and then you can press the star key which terminates the calculation and it prints the grand total on the paper and we're ready to start again. The controls are fairly straightforward. This slider switch sets the number of decimal places. It's currently set to floating point mode because that's what I'm used to. Normally for financial use you'll have it on two or three for the number of decimal places. So on two it will always display you know sense or pence or whatever currency you're dealing in. Plus it is interesting because in plus mode any number you enter is automatically treated as hundreds. So to get 1.00 you would actually type 100 and it will automatically insert the decimal point for you. Let's put that back on F. Print just turns the printer on or off. We have it on because the printer is cool. Clear entry just clears the last thing you typed. If you made a mistake C resets the calculation. That's basically it really. Apart from the grey buttons. The grey buttons are complicated. So equals, divide and times are used for making multiplications and divisions. These are infix operations. I've been playing with this for a while and I just cannot get my head around the data model. The way the infix operations correlate to the postfix operations used by the adder is weird and the manual is inscrutable and it gives you lots of examples but doesn't explain why it works. So like you can just do simple multiplications like 10 times 20 equals 200. It's printed all out nicely. It's given us 200 on the screen. But let's try 2 divided by 3 which gives you 0.6 recurring as you might expect. But now if we do say 6 and equals. So it remembered that I divided by 3 and when I entered the 6 it divided the 6 by 3 to give me 2. Which is very convenient if you want to multiply or divide long strings of numbers but not intuitive. And the way this works with the adder is even stranger. So if I like to add another 50 that gives us a grand total of 100. We can say multiply that by 0.5 which gives us 50 and it thinks it's terminated the calculation. But if I now press plus it shows 150 on the screen. So it's actually added the 50 to the previous calculation which wasn't reset even though it says a star on the transcript which is really confusing. I mean it's useful for doing stuff like tax. So let's try that again. It's just clear everything. So 50 plus 50 plus say we want to add 17.5 percent tax times 17.5 plus the percent button. So that's calculated that 17.5 percent of 100 is 17.5. Press plus and we now get 117.5 which is what we expect. And a special transcript entry. So that's weird. The I mean useful but weird. The memory is fairly straightforward. I mean you can add stuff to the memory and recall this one. That works perfectly normally. Given that it's got a primary accumulator for the adding machine part the memory acts as a secondary accumulator. So I imagine with a bit of practice you could actually do fairly complex running calculations with this particularly if you can get your head around these. The hash key is it prints a label on the printer. So if I just do around a number and press hash it just prints it left justified. It doesn't it's not part of the calculation. You use this that to divide up the transcript. So the transcript is the most important part of the whole thing. What this is for is adding large columns of figures from something like an account book. Where not only do you need to have the right answer afterwards but you need to be able to prove that it is the right answer. So the transcript is important because you can go through the transcript afterwards and see exactly what you typed in. You know where all your mistakes are. Assuming you made any. Let me just tear that paper off and show you. So this gives accountability which is a really good idea to be honest. The fact that it's on paper in hard copy means that there are no computer records to get wrong. You have a completely accurate record of every button you pressed on the thing. I mean this is still why receipts you get from shops have a hard copy transcript. Anyway that's the thing in operation. I need to get this thing off the flux paste and zoom in on the printer because that's the other really interesting thing about this. So I think time for another cut. So here is the printer in all its glory. It's a wonderfully tiny thing. I mean compare against the size of my fingers. The whole thing is what less than 10 centimeters across by a long way. Hang on I have a ruler. Seven centimeters almost exactly. As far as I can tell it operates off a single electric motor and one maybe two solenoids. So it's what's called a chain printer. This printer doesn't actually have a chain as such. Instead it's got this rubber belt. The letters are embossed on the outside of the belt and the belt rotates around these two wheels. It's called a chain printer because the early printers actually did use chains with the type arranged in a row. The way they work is the belt rotates until the letter you want is under the printhead and then the printhead fires pressing the letter against the paper usually through a ink ribbon. This one's a bit different. Instead the the belt itself rolls against this foam wheel with ink on it. Originally it'll abuse some kind of sticky burrow ink which I don't have any of. So I'm just using ordinary fountain pen ink which I drop onto the print wheel using this non-hyperdermic syringe. The print is a bit faint and I notice it's actually a little bit fainter than it was when I started doing this so I might need to put some more on. The printhead itself is sprung. It advances along under the control of I believe a can and a cam and a solenoid inside. So the way it works is it pushes the printhead along one notch at a time, waits for the belt to rotate and then another solenoid prints a letter. The reason why the printing is irregular let me just type a large number for you and then push the button. The reason why that prints irregularly is because it has to wait for the appropriate letter to come round under the belt. So let me actually do a calculation and you can see it in a bit more, see it in action. So 123 plus, 99 plus, 1.234 plus, get the subtotal. You can see the letters barely line up. Let's try a big number. Let's try a multiplication multiply that by, that's a subtotal, 0.12. Add that together and let's just push the hash button. Now this is interesting, this happens occasionally. Normally the hash sign goes on the left hand side, sometimes it appears on the right, I'll press that again and see what happens. Okay it's doing it fairly consistently. I don't know why it does that. Let's just try another number, 125 hash. Yeah there must be a reason. As I say, as you've probably gathered from me talking I don't really understand this thing. It comes from a completely different world of calculators than I'm used to. So I found my slow motion camera. This is playing back video at a third or real time so we can now see more details of how the printer mechanism works. You can see the belt rotating carrying letters to the printhead and you can see the printhead firing. This all appears to be controlled by this little cam in the bottom left. When it's in one position the belt rotates. When it's in the other the printhead fires an advances. There's also this other cam underneath the printhead. This one appears to control whether the head advances or returns back in its spring to the home position. It's a masterpiece of simplicity and the whole thing is controlled by four wires. I will just remove the ink roller. Let's see if this focuses. Focus more or less. It's a very very small foam wheel. I put ink on it by simply taking a drop off the bottom of the syringe. This is a hobby syringe so the end is flat. It won't actually go through skin. That's quite a big drop. Roll the thing around a bit. The ink collects behind the roller. So now we reinsert the ink roller. Attempt not to drop it because it will get ink all over my workbench. Let's type in a big number and press the hash key and it's a bit darker. I was expecting a certain amount of splotchiness to be honest because that's what happened last time but apparently I was lucky now. Yeah really I should be using black ink for this but I just don't have any. Anyway there you have it. A brief and not terribly informed tour through my shiny new financial calculator. I don't really think I have any particular use for this. I mean you could use it for making till if you know I ever wanted to sell anything in a market stall. It would be perfectly suitable for this but I don't honestly. This machine is not in particularly great shape. Some small child has scribbled on it with a pen. I did my best to clean it off with IPA. Well I assume a small child who knows. It does come with the box and the incredibly badly formatted and folded manual which contains many examples in multiple languages but no actual explanations. So I might attempt to flog it off in eBay but I suspect these are not valuable and it won't show up anywhere. Or I may just prop it on a shelf somewhere because it's a rather nice looking piece of kit. Anyway I hope you enjoyed this video. Please let me know what you think in the comments.