Sharp Compet 18
 

Hi folks

my neighbour found this thing at Sainbury's by the bins, I think it's an adding machine from the 70's (judging by the Nixie display) but oddly it doesn't have an 'add' button?

Anyway it appears to work, all it needed was a two pin power cord, which luckily I had in the back of my early 70's Teac 3340S

Any info?

Re: Sharp Compet 18
 

It looks like one of those old calculators where you had to add the two numbers to the memory.
I can see the M+ button on it.

Re: Sharp Compet 18
 

I found this site with similar machines, but not the exact one. http://www.vintagecalculators.com/ht...compet_22.html

There appears to be a switch on yours that has a + on it. I find old calculators fascinating to look at despite being a mathematical dunce :) I'd be interested in what others might be able to tell us about it.

Re: Sharp Compet 18
 

Nice find!

A quick search reveals it was introduced in 1969. The display appears to be a vacuum fluorescent tube, not Nixie tubes. Nixies have an orange glow. VFDs are usually blue or green.

History of Sharp calculators, including the CS-18D translated from Japanese: https://translate.google.com/transla...pd/sharpd.html

And this page in German also has your model: https://www.schlepptops.de/wiki/inde...e=Sharp_CS-18D

The Japanese page suggests that Sharp switched from using nixie tube displays to a newly-developed fluorescent display in their previous model CS-16D. This was because an American company (Burroughs) held the patents to the Nixie tube. Licensing fees were high, and Burroughs imposed a condition of license that meant Sharp could not export their Nixie tube calculators to the USA.

I'm guessing that the = key also doubles as 'add'. For example, if you typed 60=17= you would see the equivalent of 60+17=77 on the display.

Re: Sharp Compet 18
 

Nice!

These 'adding machines' were often called 'totalisers' and you could set them to increment or decrement.

Example: switch set to increment. Enter first number, hit =, enter second number, hit = and the display shows the two numbers added together. Keep on entering numbers and hitting = and the total goes up appropriately.

Or: set switch to decrement. Enter first number, hit =, enter second number, hit = and the second number is subtracted from the first. Keep on entering numbers and hitting = to keep on subtracting.

The point of doing it this way is that you wouldn't hit + when you meant - or vice-versa: the + or - was set in advance of you doing your 'run'.

I remember them being used like this to check daily ledgers: you started off in increment-mode to add up all the day's transactions to get a total, saved the total, then flipped the switch to decrement and went back through the transactions subtracting them from the total you got first time round.

At the end of the second 'pass' you should see zero - anything else meant you had made an entry-error somewhere and had to do it all over again!

Re: Sharp Compet 18
 

Many thanks for the interesting replies and links guys. Seems like it's potentially almost 50 years old and a bit of a rarity?

Hamid and G6, yes the '=' is indeed the add function.

A couple of pics of the nice bright florescent display, note the quirky '0', and of the Enigma like switches. The rotary switch goes from off to 0 to 6

I expect it should scrub up nicely, will post a picture after

Re: Sharp Compet 18
 

That's a great find, well done. Very interesting piece of equipment, and it will clean up well as you say.

Maybe if you set the slide switch to X it will multiply by the number the rotary switch is set to when pressing = ?

Re: Sharp Compet 18
 

That's a lovely example, should clean up really nicely with a bit of work.

Aside from the odd dodgy contact machines of this type from this period these tend to be pretty reliable. Often the biggest shortcoming was the lack of any form of debounce circuitry in many models which could quite quickly render a machine with an even slightly touchy key contact almost totally unusable. Especially with some of the "inventive" ways some companies tried to reduce the component costs for the keypad.

I've a similar example here that's a little later and sadly has lost the stylised display, using a single flat panel VFD. This earlier one looks far more visually appealing.

Re: Sharp Compet 18
 

Normally a rotary (or thumbwheel) switch on such desktop calculators is used to set the number of decimal places. Some machines were fixed point (and always worked to/displayed the number of places set) others were floating point but let you round or truncate to the number of places set on the switch.

Re: Sharp Compet 18
 

Thanks for the info guys, apologies for the late reply.

Paul I couldn't actually decipher what was happening when I changed the slide switch? Tony, correct the switch sets the decimal point. I haven't spent much time on this, it's more of a curiosity to me but glad it's been been saved from the dump at least.

I gave it a wash and brush up and it look very nice, the pictures really not doing it justice