I saw one of these in 72, a local architect was using it and I was told to stay away from it as it was the most advanced electronics available. 10 years later while working in the repair dept. of an office equipment supplier I found the same calculator gathering dust in the back of a drawer.
"I saw one of these in 72, a local architect was using it and I was told to stay away from it as it was the most advanced electronics available" I hate people like that.
Around that time my parents gave me a Casio calculator with a vacuum florescent display. (to maybe replace my slide rule?) It had an appetite for batteries and no "scientific functions". But, it's the thought that counts. It probably cost a small fortune.
Yes, that is the General Instruments GI250 calculator on a chip. If you think 4 digits isn't enough for most calculations, you're right. The math is done internally on 8 digits and the two groups of 4 can be swapped using the key.
Yes, this is the General Instruments GI-250, which beat the Intel 4004 to market as the first microcontroller, though it had a ROM mask as a 'calculator on a chip' (and by some accounts is the great-great-granddaddy of the PIC microcontroller series). It was first available in 1971. The power jack is a mod - the original power connector is another weird pin arrangement. The key pad is gold plated (not copper), since Litton wanted this to be a high end product. At the time, keyboards were not 'off the shelf' components, and using a stylus dramatically lowered the cost. The same chip, with an updated ROM mask was used in the more conventional Litton Five calculators (with buttons, and 8 digit display) that came out a year or two later. The chip was designed in Scotland, UK by a team of four, one of whom is my father in law. He still has the first prototype and the hand-drawn chip layout diagrams (MOS ratio logic).
Logo is GI, General Instruments Microelectronics. Famous for AY-5-1013 UARTs, various TV game controller chips, the AY-3-891x sound generators (ubiquitous in home computers in the 80s, a key to the sounds of the era), and the PIC1650, the first in the PIC series that Microchip now market. I worked on two of the lesser known GI microprocessors (LP8000 and CP1600) in the 70s and early 80s, before moving onto Z80s.
On the subject of calculators in school in the early days I argued with my grade 8 teacher (when we first got calculators in school) that we should be allowed to use calculators on all tests to get the practice in...and his response was, "Do you think everyone in future will walk around with a calculator in their pocket?" Look at us today. But even in high school I had a calculator watch.
What year did this discussion with your teacher happen ? Just curious. My first calculator was a TI 1250, around 1975 or 76 when I was in grade school.
@@konglives4453 It was grade 5, late 70s, and I don't know the exact model number but it was a Commodore LCD basic (not scientific) function calculator, maybe an LC925. At home my father had a VFD Unitrex basic calculator that was only taken out a tax time and I wasn't allowed to touch. Around that time I got into Commodore PETs only able to get my hands on one taking continuing education programming courses at the local college, and then I was the school's computer expert at age 11 when the school started getting PETs.
I'm all in favor of calculators in the classroom. It allows the kids to go into higher math earlier while skipping the mundane stuff. I graduated HS in '73 and I only took one year of basic math. "Basically" arithmetic. That summer I served an apprenticeship along side my father for the tool and die trade. With my first two paychecks ($200) I purchased a Unicom Rockwell engineering calculator. That got me into trigonometry and algebra immediately. One could make the argument that the student should know the "how and why" a particular equation arrives at the answer. In the real world its not necessary. When you're plying your trade and getting paid by the hour it's best to get the right answer ASAP.
In the same timeframe, I was working for Monroe Calculator (Orange NJ). It was also a Litton subsidiary. We made the exact same calculator with Monroe branding. That's actually an 8 digit calculator. You'll find a "swap" key on the keyboard which swaps the most and least significant 4 digits to the display. The chip is from General Instruments. This was a super low cost device (under $100) hence only 4 vfd's and no keyswitches. A full featured 4 function handheld at the time was around $375.
I remember the no calculator rule when I was in school and then I went to an electronics vocational school where a scientific calculator was required equipment. Took a little while to shake the feeling that I was cheating somehow.
I'm all in favor of calculators in the classroom. It allows the kids to go into higher math earlier while skipping the mundane stuff. I graduated HS in '73 and I only took one year of basic math. "Basically" arithmetic. That summer I served an apprenticeship along side my father for the tool and die trade. With my first two paychecks ($200) I purchased a Unicom Rockwell engineering calculator. That got me into trigonometry and algebra immediately. One could make the argument that the student should know the "how and why" a particular equation arrives at the answer. In the real world its not necessarily so. When you're plying your trade and getting paid by the hour it's best to get the right answer ASAP.
It makes sense that he engraved his name on it; that was pricey little bit of kit in 1972. I seem to remember a price tag of nearly $200 when they first came out. That doesn't sound like much today, but in 1972 that was sizable chunk of money. I think the conversion puts it at about $1100 today, though that's just a very rough estimate. Considering I can buy a calculator now for $2 or so that does more than this one could, and needs no power aapter.
I first used a pocket calculator in 1974 a teacher brought into class just before the Christmas break. We students were mind-blown by what that little device could do. (I still think that may have been a promotion; and I soon got one for Christmas). By the next school year, which was my senior year in HS, we were allowed to use calculators for doing the math on our chemistry tests. There was no turning back.
In East Germany calculators were introduced in schools in the late 80s. And you needed a signed form from the school to buy the calculator, because it wasn't freely available. They were called "SR 1" (Schulrechner 1 = school calculator 1) and the price was 123 DDR Mark, really expensive! But mine still works fine today. It's very sturdy. Also the official lesson plans in 7th grade were attuned to using the calculator. So we were late to the game but went full in.
That is a really cool calculator, and works great. I read that they used the stylus to save money, and it has also probably made it more durable after all this time.
That brings back memories of a fellow student in my DC circuits class who had one of those. Clicks were annoying, especially during a test. I got him back in AC circuits when I was able to purchase an HP35 calculator. Love your videos!
GI did so many interesting chips - calculators, video games, microprocessors .. etc. I think they ended up as Microchip, Would like to read more of their history.
I like this old stuff. The oldest calculator is my Sinclair Cambridge from 1973. I have also a Ohio Scientific Superboard 600 1978 (buy it 1980) with integrated Keyboard/TV connection and a Mac 128K from 1984 with Motorola 68000. so this Hardware needs always a Keyboard for inputs. The price for a good switch was very expensive, 80 pieces for a full keyboard. A stylus came back with the Apple Newton 100 MessagePad 1993 and the first touchscreen. It’s nice to see a stylus 1972 with metal pads.
Really enjoyed this one Fran, in 1972 I was 17 years old and getting into electronics , this was cutting edge customer technology back then along with Clive Sinclair products being released here in the UK. I am now retired having worked in electronics all my working career. To see this 50 year old calculator working again is fascinating along with digi clock teardowns you have recently done. Best wishes.
I used a TI calculator in college in 1974 and they were encouraged. One student had one like you have there. It got the "ooohh's" and "ahhhh's" but the TI was easier to enter numbers, especially when taking a test.
I'm all in favor of calculators in the classroom. It allows the kids to go into higher math earlier while skipping the mundane stuff. I graduated HS in '73 and I only took one year of basic math. "Basically" arithmetic. That summer I served an apprenticeship along side my father for the tool and die trade. With my first two paychecks ($200) I purchased a Unicom Rockwell engineering calculator. That got me into trigonometry and algebra immediately. One could make the argument that the student should know the "how and why" a particular equation arrives at the answer. In the real world its not necessary. When you're plying your trade and getting paid by the hour it's best to get the right answer ASAP.
You always have the best content. I miss the days where crafting electronics was an art form and not just mass-produced ICs under blobs of epoxy. (though it's a lot cheaper of course these days)
I'm really surprised you didn't recognize the General instruments logo. You are about the same vintage as I am and GI chips were everywhere in my early days of electronics.
The Litton logo by the Royal name is one that I have not seen in a long time. Litton was a defense contractor that dabbled in a few consumer products including microwave ovens. The Litton name was pretty huge in that genre in the 70s and 80s.
The gold chip is is GI - General Instrument. They made a lot of sound chips bitd. The AY-3-8910 and AY-3-8912 were used on a lot of Arcade game PCBs and home game consoles.
I went to high school back in the 70's and we were told NO CALCULATERS, that we needed to understand the process of math and calculators would make us lazy. Didn't work on me too much, am still lazy. LOL Take care and God Bless from Florida.
I'm all in favor of calculators in the classroom. It allows the kids to go into higher math earlier while skipping the mundane stuff. I graduated HS in '73 and I only took one year of basic math. "Basically" arithmetic. That summer I served an apprenticeship along side my father for the tool and die trade. With my first two paychecks ($200) I purchased a Unicom Rockwell engineering calculator. That got me into trigonometry and algebra immediately. One could make the argument that the student should know the "how and why" a particular equation arrives at the answer. In the real world its not necessary. When you're plying your trade and getting paid by the hour it's best to get the right answer ASAP.
In some of the classrooms at the "Junior College" i used to attend had a Monroe Litton desk calculator with Nixie tubes. It was something like 15 digit - must have been expensive when it was new. I was surprised to see it there in 1987.
Nice. Since I retired recently I’ve had time to go through all my auto and electronic test equipment and fixing all the leaky batteries. Getting good at it with my Dremel tool with a fine brass brush and contact cleaner and DeOxit spray cleaner.
Wow, that's a hell of a piece of history from the "calculator war" of the 70's. Hope you take some photos and upskirt shots for the vintage calc museum. Hard to imagine now, but someone put down a week's pay for that .. and every nerd in the shop waited a turn to do 2+2.
In my high school trig class in 1973, calculators were required. The school purchased a bunch for students that were unable to buy their own. They were handed out at the start of each class for the duration of that class. Tests were designed such that you had to use the calculator, or you'd never finish the test. I bought my first calculator that year -- an HP-45, using money from my morning paper rout. I still have it, including an HP65 and HP16c. They all still work. I still use the HP16c, every day, to this day.
Hi fran I love your videos, keep them coming. I had a Calculator when I first got married in 1981. I think I paid something like £220. I don’t know what that equates to in dollars at that time, but it was an awful lot of money, and I thought I was the bees knees, you can buy a Calculator now, or you can be given one for less than the cost of the batteries what a crazy topsy-turvy world we live in! Keep your videos coming, I always always enjoy
Some other have already added info on this calculator in their comments, and I will try to add some more here based on my own resources. This calculator was called the "Digital III", and was introduced in late 1971. It was made in the USA by the Royal Consumer Products division of Litton Industries in Connecticut. It was "announced" in the January 1972 edition of "Electronics" magazine. It's suggested retail price was $140 USD, adjusted for inflation this would be something like $1000 USD today. As this was considered to be a "low cost" calculator at the time, the three major design decisions allowing it to be so "inexpensive" were the use of a "calculator-on-a-chip" integrated circuit, the four digit display (although since the calculator circuits did the math for an 8 digit display, it was necessary to 'scroll' the display left and right to show only four digits at a time, hence the "" key), and the use of the electronic 'stylus' contact pads instead of a mechanical keypad. Keep in mind that in the early 1970s, electromechanical keyboards and keypads were both complex and expensive (and usually bulky), and use of such a keypad on this calculator would have driven the cost up even further, and by a significant amount. So Royal decided to use the simple and relatively expensive stylus & contact-plate scheme. By the way, those keypads are gold plated, not plain old beryllium copper! The "calculator-on-a-chip" was the General Instruments model 250, which was one of the contenders for first usable chip of its type. This model was also made more expensive by the use of the vacuum-fluorescent displays and their supporting high voltage power supply circuit. As noted in the video, this model was nominally powered by a bank of 6 Ni-Cad cells, making a supply of 7.2V, but as it was power hungry, there was provision for powering it from a "wall wart" power supply. At the same time Royal designed and introduced this "Digital III", they also produced a less expensive model, their "Digital IV". This had the same case (but in beige instead of the "Royal" blue color), same battery and power supply, and same stylus entry scheme. The differences were that the "IV" used an 8 digit LED display, and so accordingly used the General Instruments 251 "calculator-on-a-chip" IC, which better suited the display scheme. Because the display could show all calculated digits at once, there was no need for the "" 'scroll key' that the model "III" required, so that was deleted from the stylus pad arrangement, and the "+" pad was made twice as large to fill in the empty space. Suggested retail price of the "IV" was about $800 in adjusted 2022 dollars, a significant cost reduction over the model "III".
Reading your description reminded me of the Star Trek episode "City On The Edge Of Forever". Super cool episode Fran and thanks to Craig for sending the calculator. 🖖
4:42 The neatness of the axial parts suggest automated insertion. 7:72 These axial parts too. The radial parts and everything else suggest hand assembly.
Man, I'd really love to hear the story behind the development of that thing! I mean, calculators with actual buttons were already on the market. And Royal was a //typewriter// company for gods sake! Seems like the idea of a box with some keys on it would not have scared them off. So what weird series of ego clashes or dumb decisions or just plain not paying attention and taking 10 years too long to develop a product led to this still-born disaster? I bet it's an interesting tale.
It was far from a disaster. Litton made millions from the Royal Digital (and Monroe) calculator line. The weird design decisions made this the first "pocketable" calculator (previous devices were desktop only), and a fraction of the price of any other competition. It's worth reading on the "calculator wars" of the 1970's - this was one of the earliest machines on the market and along with Intel, Mostek and others kicked off the evolution of the microprocessor.
@@LockFarm I meant a design disaster, not a sales one, but the ones Litton made money from were not this one. Have you ever seen one of these in person? I certainly haven't. This thing is more like a proof-of-concept not meant to be sold, only somebody sent it to the wrong department and it got produced. It's a calculator that almost seemed deliberately designed to make you not want to use it. I'm sure I would have opted to keep using my Pickett log-log stick. ;)
Love the calculator videos! One of these days, I NEED to clear my desk, so I can have the _room_ to get my SCM (Smith Corona Marchant) Cogito 240SR and my Hewlett Packard HP9100A opened up so I can check them out... The 240SR powers on and allows number entry, and used to work perfectly, but after moving a decade ago, the entry register will no longer transfer into the operation register. The HP9100A was sold to me as non working, so I have no idea how extensive repairs on it would be.
I lived through the no calculator days in school. I started high school in 1971 and calculators were available, but not very affordable and that was how the principle explained why calculators were banned. It was because they would put some people that could not afford them at a district disadvantage. Once I moved on to university calculators were allowed. However, in the bulk courses I took (physics, mathematics and logic) they were not of much use. The only times they came in handy was doing lab work where actual numerical results were often sought. General Instruments?
My HP35 (of similar vintage) still runs great! (I have also had to change batteries, and now have a USB charging cable in addition to the wall wart). But then again, so does my decilog slide rule that I used in high school (a boys-only nerdy college prep Catholic school in Chicago), and at the Astro Science Workshop (taught by Northwestern University, University of Chicago, and Adler Planetarium faculty to promising young high school (and some very precocious elementary) science students
Looks like a Stylophone. I've been wanting to get one of those, at least a reproduction, but the price is a tad steep for me. I suppose you could adapt it to run on Li-ion batteries, but it wouldn't be worth it if it is just going to be a shelf queen.
I recently discovered a SOBAX 600 in a trash pile. I took it home to find 14 nixes a displaying zeros. I did figure out how to throw it in a check mode for each nixie but I can’t find any white paper on it. One day I’ll get it working. Basically no number inputs on the matrix work. It has 5 different slot boards. All fully populated with transistor arrays. Truly a first see experience. Anyways thanks for sharing your calc. God Bless
Nothing wrong with learning math without a calculator. That said, there is definitely a threshold where avoiding one impedes the rate you can progress through new material.
I wonder if those old batteries are NiCd, and if they are, would six (much smaller) NiMH cells serve as a drop-in replacement? It would be kinda neat to get that working again completely untethered.
@@russellhltn1396 It was probably just cost cutting. A stylus to touch the bare PCB was surely much cheaper than a full keyboard. Althogh the thick gold plating added to the costs, which would not be absolutely necessary with a conventional keyboard.
@@JaneChristensen. Not many, especially the foam and foil type ones. Some used metal contacts, those are still fine usually. In bigger, desktop calculators they sometimes used magnets and reed switches, those are eternal. OK, a few hundred years later the magnets might become too weak 🙂
Cute lovely stuff you got here! Gold-plated traces on a double-layered board and bluish enclosure gives off a Tetronix vibe, haha! I love the build quality. I'd replace that foam rubbish altogether. Pity they used a tube rather than LED/bulb for the negative sign. A complete waste if you ask me. Latex sounds a lot sexier than silicone, haha!
In my first year of HS (1969) the basic math class had four Olivetti mechanical calculators. Before we learned how to use one we got a lecture from the teacher about NOT dividing by zero. Within a week two of them were down for repairs. They actually required a mechanic to "reset" them if they got locked into an endless divide by zero situation.
Ive never seen one like that Fran, must be an American issue. The only one I remember when I was in the last year at UK secondary school and it was all plastic construction both buttons and case. I do remember the red LED watch when it came out as my older brother purchased one where the button needed pressing to illuminate the time.
Sush a cool device! I wonder if it is an early microcontroler, with masked program; or some kind of hard wired sequencer and logic automaton. It does not look like the intel 4004, made originaly for calculators, it needs more chips around it.
I kind of wanted to see the classic 10/3 and then taking that result and *3. To see how it handles rounding. I'm guessing it would just say 9.999 but still. :)
I wonder when that design originated as it may have been outdated by 1974 as Sharp, Casio and Texaa Instruments had far more sophisticated calculators by that time.
until the late 80s, devices with built in battery often used the battery as a voltage regulator. So never plug in such a device if the battery is missing or may be dead. E.g. most Commodore pocket calculators come with a 6V PSU but can't tolerate much more than 5V, the built in NiCDs limit the internal voltage to ~4.8V. the unregulated original PSU will give you around 9V! 4 digits is actually plenty, a sliding ruler gives you 3.5 digits at best. The scales give you only 3 digits without a decimal point (you have to keep the decimal place in your head) and you can only tell that it is more or less exact, a bit more or a bit less, hence 3.5 usable digits.
What a cool calculator! It probably wouldn't take too much work to retrofit a couple of 18650s if you wanted to start using the calculator on battery power again, but I suspect there are a dozens of other projects in the queue right now (relatable).
That seems like something of historic interest, so I'm a bit shocked to see you randomly clipping wires. I'd think you'd want to try to keep it as original as possible. Thanks for the video, fascinating piece of hardware!
You really should clean the boards and other things affected by the battery leaks with vinegar (weak acid). Neutralizes the alkalic electrolyte. Be sure to rinse well afterwards or you'll have acid corrosion instead.
