Archive for the ‘Calculator’ Category

Yet another LONG overdue post

July 17, 2014

Greetings to all,

With as long as it has been since I’ve posted here, many might think that I’ve fallen off the face of the earth. I’ve also not posted much on the Old Calculator Museum website, which may further add to such speculation. This posting is to say I’m still around, and have been preoccupied by a lot of other stuff in my life that has consumed the vast majority of my time.

I am getting along OK. A lot has gone down over the past couple of years, some of which is not all that great, but it is what it is, and I’m working through the challenges. But, I’m not going to bore my readers with that stuff. The important stuff is old calculators. And, there has been some stuff going on there that is exciting.

The coolest thing is that just two days ago, the museum took delivery of an amazing new addition to the museum. I have been searching for one of these machines for many, many years, and finally, one now makes its home here. The machine is a Wyle Laboratories WS-02 Scientific. I’m extremely excited about this addition, as this is a very uncommon, and also somewhat historical machine due to what its development spawned.

For those that aren’t aware of the story, there is an essay on the Old Calculator Museum website entitled The History of Compucorp that goes into a lot of detail of how Computer Design Corporation was spawned from Wyle Laboratories.

The Wyle WS-02 is the second (and last) generation of Wyle Labs’ calculators. Functionally, the earlier WS-01 is identical to the WS-02, with the difference being the medium used to store the working registers of the calculator. The WS-01 uses a small fixed-head magnetic disk, not unlike the disk drives in computers today, but storing on a tiny fraction of the amount of data that today’s disk drives (or even disk drives of computers in the 1960’s) hold. The disk drive proved to be rather temperamental which led to a lot of problems with WS-01 calculators sold to customers. As a result of the difficulties, the calculator engineering team did some redesign of the WS-01 to utilize a magnetostrictive delay line (a loop of special wire through with torque pulses representing ones and zeroes travel through the wire at sonic speeds resulting in a time delay, or storing of the bits in the wire as they circulate through) to replace the disk drive. The resulting machine was the WS-02.

The museum received the WS-02 calculator in amazingly good physical condition. The main issue is oxidation of the plastic keycaps on the keyboard, which makes a white film over the keycap that makes reading the legends on the keys somewhat difficult. It is expected that this will be able to be remedied, but care must be exercised to make sure that the legends aren’t damaged or the structure of the keycaps is not compromised in the process. Also included in the acquisition was the model PC-01 punched card reader, that plugs into the WS-02 calculator to provide keystroke programming, via codes punched into special cards. The card reader appears to be in good condition physically. Along with the calculator and punched card reader, two original manuals for the machine were included, which is amazing, as documentation is usually lost with time.

The machine was originally purchased sometime in the mid-1960’s by a company that was involved in land development, surveying, and construction. The calculator was used to perform surveying and construction calculations. It is not entirely clear, but the WS-02 and PC-01 may have been part of what is called a WSS-5 or WSS-10 system. The WSS stood for Wyle Scientific System, which was a small desk, with a compartment with electronics in it that the calculator and punched card connected to that provided additional storage registers (8, 16, or 24 registers) and patch boards that could be wired with program steps. If the WSS-5 or WSS-10 was part of the system, it was not retained. The company used the machine as part of its operations until sometime in the early 1970’s, at which time the company suffered tough times, and ended up closing. When the offices were being cleaned out, one of the employees saw the calculator sitting out on a table (which may have been the WSS-5/WSS-10), waiting to be thrown out. He asked his management if he could take the machine, as he thought that it was kind of cool. His manager said that it was fine to take it, and he took it home, and stored it away in his basement. The machine was in full operating condition when it was put away in the basement. The machine remained there all these years.

In early May of this year, I received an EMail from the owner of the machine, saying that he had pulled the calculator out of his basement, and did an Internet search on it, and found the Old Calculator Museum’s WANTED  page for the Wyle WS-01/WS-02 calculators. The EMail asked if the museum would be interested in acquiring his machine, as it was unlikely that he would be doing anything with it, and felt that it should go to a place where it would be preserved and documented. Over the following weeks, and agreement was made, and in early July, the machine was packed up and shipped from Rhode Island. The machine arrived at the museum on July 15th, in an amazing custom-built crate that the owner crafted to assure safe transit for the machine.

The machine made the trip with no problems at all. The packing was incredible, and essentially the crate could have likely survived a drop off the back of a truck with no ill effect to the calculator.

Now begins a slow and methodical process of checking out the electronics in the machine to assure that things like power supply capacitors, edge connector sockets, and wiring harnesses are all in good condition, and if any faults are found, properly repaired. It will likely be some time before the machine will be ready to attempt to power up, but it is hoped that it will be able to be made fully operational.

Of course, a detailed exhibit for the calculator will be created for inclusion in the Old Calculator Museum website.

On other calculator-related topics:

– The Monroe EPIC-3000 calculator that was written about in old postings here has been restored to full operation. It is in the process of being documented for its exhibit in the museum. It is quite exciting to have this calculator working fully, as it is very much a hybrid of electromechanical and electronic technology, and the mechanical aspects of machines like this can be quite difficult to diagnose and repair.

– The museum received a donation of a huge amount of old Friden parts and documentation. Included in the lot was a large number of copies of Friden’s internal magazine, Friden News, which I’ve only begun browsing through and have discovered a lot of very interesting historical information, including introduction dates of Friden calculators, as well as stories about the development and early sales of Friden’s first electronic calculator, the EC-130. There is also a lot of information about Friden’s other products, including the Computypers (small-office billing machines/computers), Flexowriters, Punched tape equipment, Postage Equipment, and in later editions, information about Friden’s computer system, the System 10.

– A number of calculator donations and acquisitions have come in: Addo-X 9958 (essentially a Sharp Compet 32 in beautiful condition), Bohn Omnitrex 12, a Master H-2, a Wang 370 Programmer (fully operational after minor repair work), a Monroe EPIC-2000 (needs some work), and an Wang 360SE that needs some power-supply work. It is just a matter of time until I can get these documented and up on the museum website.

I wish all those who read this posting the best of everything.

06-Sep-2011: A long overdue update

September 6, 2011

Hello, all,

I hope that this post finds the folks that visit this blog are doing well.

It has been a long time since I have posted here. Quite a lot has gone on over the past year or so..a quick overview

On the new calculator front, New Acquisitions:

  • Monroe 820A(non-working), thanks to a generous donor,  to go along with the Monroe 820 that the museum already has (also non-working).  I am hoping that between the two of them I can get one working. This is the only CRT-display-based machine that Monroe made, and it is quite uncommon.
  • A Monroe EPIC 3000 (in very nice shape, and mostly working), and a Monroe EPIC 2000 with some mechanical and electronic problems.  In time I hope to get the EPIC 3000 completely working…it seems like the problem is just a bad connection in the cable that connects the keyboard/printer unit to the electronics package.
  • A Sharp Compet 21(CS-21A).  This is an extremely rare machine that looks identical to the Sharp Compet 20, but with electronics changes that allow it to perform square root.  The machine calculates square roots to five digits behind the decimal. The machine has problems, but I am hopeful that they can be figured out and repaired.  It tries to run, but gets very confused when asked to perform operations.  The design of the machine is very similar to the Compet 20, with some boards identical between the two, but there are definitely changes to the PP board (Program Package) that contain the sequencing logic for the machine, and addition of three unique boards, one of which appears to be a diode ROM that perhaps provides sequencing logic for the square root function, along with a significantly different keyboard interface board that probably detects the “divide followed by +=” key sequence that triggers the square root operation.
  • A Sharp Compet 32 that will shortly be on its way to the museum.
  • An additional Sharp Compet 20 that is a bit earlier than the one currently in the museum, which will be arriving soon.

Because of all that has been going on, updates to the Old Calculator Museum website have slowed to a trickle.  I have a large backlog of exhibits to create, and quite a number to update.  I also have more materials to add to the advertising archive, and some technical information to add.   The biggest enemy I have right now is time.

My job is keeping me very busy. The University started fall session classes last week, and things are really hopping with over 3500 students now making demands of the computing environment, which we did a huge amount of work on over the summer. Along with work, during the summer months, there are constant projects around the property that demand time, along with my wife’s dog agility competitions that consume time on weekends.

I must veer off-topic for a moment. We have a German Shepherd that is competing at the top national levels of competition in dog agility, and this year has been extremely successful.  Tory (our German Shepherd) and my wife, Patty, have earned entry into three National Championship competitions this fall and early next year, including the German Shepherd Dog Club of America Nationals, the AKC National, and the USDAA National.  We’ll be traveling to Kansas, Kentucy, and Nevada for these competitions, and hopefully, come home with some national championships.  German Shepherds are very uncommon to run at the national level in a sport dominated by Border Collies and Australian Shepherds.  It is a huge testimony to the athletic abilities and high level of intelligence that Tory has, and Patty’s dedication to excellence in training (both for herself, and Tory) over Tory’s 5 years of life.  You can see YouTube videos of Patty and Tory in action by checking out the channel “pattybffds”.  Just search for it on YouTube.

Once the fall and winter settle in, there will be more time to devote to my calculator passion, and I expect that there’ll be a more updates both to this blog, as well as to the museum website.

Lastly, before I close out, I am honored to be invited to a gathering of ex-Friden employees (known as Fridenites) in San Leandro, California (the original headquarters of Friden Calculating Machine Co.) on September 15th.  This luncheon gathering will have many luminaries from the heyday of Friden, including Robert Ragen (the chief designer of the Friden EC-130), Dick Ahrens (a senior engineer involved in the design of the EC-130), George Comstock (another senior engineer, who left Friden to form Diablo Systems, a company famous for the development of daisywheel printer technology), and many other former Friden employees.  This should be a fun and fascinating time.  I will try to write up a blog entry about the event soon after I return.

With all that said, I will call this entry complete.  There’s a lot more that I didn’t write about, but that captures the high points.   Wishing you all health (the most important thing), happiness, safety and security!

06-Jun-09: Fantastic Donation

June 8, 2009

Last week, the Old Calculator Museum received a very special calculator as an addition to the museum’s inventory. The machine received was a 1965-vintage Wanderer Conti printing electronic calculator.

Back in early November of 2008, the museum was contacted by Mr. Hans Boeck, indicating that he was in possession of a Wanderer Conti electronic calculator that was demo machine used by Mr. Boeck when he was involved in sales of electronic calculators in the international market. Mr. Boeck had indicated that he would be interested in donating this machine to the Old Calculator Museum. Due to a number of complications, it took quite some time for the machine to finally make its way to the museum. It arrived completely intact, a testimony to the incredible packing job done by Mr. Boeck. The Old Calculator Museum owes a supreme debt of gratitude to Mr. Boeck for making this wonderful artifact available to the museum. The Conti is a rather rare machine, and while it was sold in the US by Victor Comptometer (under OEM agreement with Wanderer-Werke) as the Victor 1500-Series, there just are not very many of these machines left around today. The museum has been looking for an example of a Conti (or the Victor or Sumlock Comptometer-badged versions of the machine) for many years. Had it not been for Mr. Boeck’s kindness and generosity, the search may have gone on for a very long time.

The Wanderer Conti was the first electronic printing calculator to print on “adding machine-style” paper tape. The Mathatronics Mathatron is historically recognized as the first printing electronic calculator, but it printed on a special 5/8ths-inch wide “ticker-tape” style paper tape. While the Mathatron had the distinction of being the first marketed printing electronic calculator, the ticker-tape style printout was somewhat unwieldy for storage and reading, while the adding machine tape printout of the Conti was something that was much more familiar to accountants and bookkeepers. The Mathatron was more targeted at scientific and engineering calculations, while the Conti was more targeted toward business use.

Wanderer-Werke AG, a company founded in 1885 in Koln, Germany, started out manufacturing bicycles. The business thrived, and into the early 1900’s, the company had expanded into making typewriters, milling machines, and by 1910, had started making automobiles and motorcycles. The company became known in Europe as a premier manufacturer of mechanical products of superb engineering. In 1927, the company began manufacturing adding machines, further expanding their business base, and making a name for itself in the European business machine marketplace. During World War II, Wanderer-Werke was a principal manufacturer involved in the German war effort. After the war ended, the company went back to its core businesses. Wanderer-Werke AG still exists to this day, serving primarily as a financial holding company for a number of businesses, as well as licensing the Wanderer brand name for use by outside companies.

With the advent of the first marketed desktop electronic calculator, the Sumlock Comptometer/Bell Punch ANITA in late 1961, many makers of mechanical adding machines and calculators began to realize that their future in the business machine marketplace may be radically affected by the advent of electronic means of calculation. It so happened that one of Wanderer-Werke’s major customers was another German company, Labor Für Impulsetechnik, also known as LFI. Founded in 1952 by Heinz Nixdorf, a brilliant electrical engineer and businessman, LFI developed complex electrical and electronic control systems for industry. Mr. Nixdorf had a keen interest in computers, and moved his business into developing electronic computing devices, developing early business-oriented small computers and accounting machines. Sometime in 1962, and arrangement was made for LFI to design the electronics for Wanderer-Werke to use in making their own electronic calculator.

LFI had a world-class electronics design operation, and had become masters in the art of designing logic circuitry based on transistors. Up until 1958, Mr. Nixdorf was the chief electronics engineer for the company, but after that, he had to start hiring engineers to help with the design process, as there was simply more work than he could handle by himself. LFI designed all of the transistorized electronics for the machine to specifications jointly developed by Wanderer-Werke and LFI. In late 1964, the first Conti (which derived its name from Wanderer’s line of “Continental” typewriters), was introduced in Europe, and was quite successful due to its convenient printing operation, high speed, and memory capability. In 1965, Victor Comptometer signed up as an OEM distributor of the machines in the US (marketing the machines as the Victor 1500-series calculators), and later (1967) Sumlock Comptometer in the UK also distributed the machines to provide a printing calculator to their existing line of Nixie-tube display calculators.

The design that was developed was truly a work of digital design art for the time. The calculator’s architecture was a bleeding-edge example of computing machine design, using a microcoded architecture centered around a wire-rope ferrite core ROM for controlling the operation of the machine (14x16x80, for a total of 17920 bits of ROM), magnetic core memory (16x14x4, totaling 896 bits), and completely transistorized control logic and arithmetic unit. At the time of its introduction, there was no other machine on the market that could match the Conti as far as the advanced computer-like architecture used in its design.

The resulting machine was built to the extremely high standards of German manufacturing processes. The design is very modular, with the electro-mechanical keyboard and printer assemblies, and power supply module stacked neatly atop the electronics. The electronics are in the form of three large circuit boards, arranged in plastic frames and “bound” at the long edge such that the boards form a “book”. The boards are interconnected by hand-wired connections along the spine of the book, along with four very high quality edge connector sockets that make up the backplane connections as well as the connections between the keyboard/printer, power supply, and electronics. The power supply takes up the right-hand side of the chassis, the printer situated in the center, and the keyboard mechanism at the front of the machine. The electronic design is based on Silicon transistors, making the Conti the earliest electronic calculator based on this transistor technology. Other electronic calculators of the time were based on earlier Germanium-based transistor technology, that used more power, operated at slower speed, and tended to be less-reliable than Silicon-based transistors. The speed of the Silicon transistors, combined with the efficient microcoded architecture of the machine made the Conti a very fast calculator. Additions and subtraction took just over 1 millisecond (1/1000th of a second), and multiplication and division took between 60 and 70 milliseconds. By comparison, the Friden 130 was roughly 20 times slower on average. Of course, the Friden machine displayed its answers on a CRT display, giving virtually instantaneous results once the calculation was completed, while the Conti had to take the time (roughly 300 milliseconds) to print its results, but for the extra time spent, the Conti gave a permanent record of its calculations, something the Friden and most all other calculators on the market at the time could not boast.

The mechanicals of the Conti live up to Wanderer-Werke’s mechanical engineering excellence. The design of the printing mechanism is relatively compact and quite straightforward, using individual print wheels for each column. The print wheels turn to match up with corresponding digit or character needed at that each position, at which time a small solenoid is fired by the electronics to lock each wheel in place. Once all print wheels are in the correct position, the mechanism drives the print wheels up against the ribbon to transfer the line of print to the paper in one shot.

The keyboard assembly is a very complex mechanical assortment of code bars that serve to encode the keys, switch contacts to turn the mechanical code into electrical impulses, and interlocks to prevent multiple keys from being depressed at once.

While there are different versions of the Conti, they all share some common features. The machines have a capacity of 14 digits. Internally, 16 digits are used (the machine uses a 4-bit “word” to encode each digit), with one digit representing the sign of the number, fourteen digits making the number, and a final digit used as a “check” digit by the electronics as an error-detecting means. All of the machines have at least three memory registers, with some models gaining an additional seven memory registers for a total of ten memories. All of the models provide the four standard math functions, with some models able to calculate square roots with one-touch ease. Fixed decimal point location is set by a thumbwheel switch. On some models, two thumbwheel switches allow setting of the decimal point location and the digit at which round-off/truncation should occur. The keyboard provides a key for forcing the current number to be rounded off or truncated based on the setting of the round-off switch. Negative numbers are printed in red, using a two color ribbon. The printer has 21 columns, and can print around 3 lines per second. Later models in the Conti line, based on the same basic design, allowed the connection of external peripheral devices such as a paper tape readers (for automatic input), paper tape punches (for recording output of the calculator), other forms of hard copy (slave printers and typewriters), and even magnetic tape drives that would record the calculator’s output to allow it to be fed to computers.

The machine received by the museum has three memory registers, one-key square root, and provides separate thumbwheel controls for selecting the decimal point position and the round-off digit position. It does not have provisions for connection of peripheral devices.

In a competitive analysis document published by Friden Calculating Machine Co. in 1965, Friden commented that there was a lack of information about the machine that kept them from performing a detailed analysis. To this day, this statement is still true, there is very little information out there about these fantastic machines. The authors of the Friden document did comment that in the demo that they saw, the keyboard seemed to be a weak point for the machine, with the comment made that operation of the keyboard seemed less than satisfactory. They also commented that the machine seemed complicated to use, with a large number of control keys.

While the Conti was not a programmable machine, the fact that it was controlled by a microcoded calculating engine meant that it was possible for custom operating firmware to be created for the machine. While not substantiated as ever having been done, the Friden document noted above does mention that customization of the machine can be done, but not by the user. Such customization would likely be done by modifying the content of the microcode ROM to implement customized functions for particular applications.

The machine does have a few minor issues known at this time that need to be worked on. First, there is a cogged belt that connects the main drive motor to the printing assembly. Somewhere along the line, this belt deteriorated, as is common with many rubber-based materials that are exposed to many years of atmospheric contaminants. Unfortunately, this belt is of a size and cog pitch that does not seem to be made anymore, so some effort and expense will have to be expended to have a custom-manufactured replacement made. Also, the main clutch that actuates the printing mechanism doesn’t completely release at the end of a print cycle (as found by manually cycling the machine through a print cycle), meaning that some adjustment of the mechanism is required. Also, the memory register selection keys (three of them) are all locked in the pressed position, which will likely require some mechanical adjustment to remedy. Along with these mechanically-related issues, the machine will need a thorough electronic checkout to assure that all is well with the power supply before even thinking about powering the machine up.

I have written to the Curator of Business Machines at the Heinz Nixdorf Museum in Paderborn, Germany, in hopes that they may have information about the Wanderer Conti calculators. Hopefully this query will result in some materials which can be used to help better document this machine in an upcoming exhibit on the Old Calculator Museum’s website.

16-Mar-09: One Step Foward… [More Wang 370]

March 16, 2009

In the last post concerning the Wang 370, the 371 punched card reader was checked out and appears to be generally healthy. In spite of this, the 370 still has problems with hanging when simple program-related functions are attempted. After looking through the logic, the first place to check is the master clock and timing chain.

The bottom cover of the 370 was taken off, providing access to the backplane connectors. This would be the best place to connect an oscilloscope to monitor signals on the backplane.

One Logiblock (#571 – System Control) contains the master clock oscillator and the three timing chain flip flops connected as a simple three bit binary counter. A scope probe was placed on the backplane pin containing the master clock signal. The 370 was disconnected from the 360E electronics package, and the 370 powered up. Immediately, the oscilloscope showed a reasonably clean, symmetrical square wave at a frequency of about 36KHz. It was clear that the master oscillator was running just fine. Next, the probe was moved to the output of the first stage of the timing chain. Interestingly, the output was static, with only tiny (a few millivolts) transients occurring occasionally. If the flip flop was working properly, this output should be a square wave running at half the frequency of the master clock. Clearly, it wasn’t. This in itself was a big clue. If the timing chain isn’t running, the logic states that sequence the 370’s logic can’t operate properly. This could well be the reason why the 370 hangs when trying to perform a simple single-step operation.

Just out of curiosity, the outputs of the two other timing chain flip flops were checked, and they too were static, which would make sense, as these flip flops are clocked by the action of the first flip flop.

The outputs of the timing chain flip flops are passed across the backplane to another Logibloc (#570 – System Timer) that contains, among other things, combinatorial logic that decodes the outputs of the timing chain flip flops into a series of timing signals that choreograph the operations of the 370’s functions. To see if perhaps there might be a fault on this board, the board was removed from the backplane, and the 370 powered back up. This time, each of the three timing chain flip flop outputs (T1, T2, and T3) were wiggling the way they should, with the first stage output at half the speed of the master clock, the second stage at one quarter the rate of the clock, and the last stage at 1/8th the master clock frequency.

It seems that something in the System Timer Logibloc was interfering with the output of the first stage of the timing chain. The combinatorial logic on the System Timer board consists of diode-resistor networks configured as AND gates, with transistor stages providing inversion and/or buffering of the gate outputs. There are a number of these logic networks that decode various states of the timing chain flip flops. All of the diodes in the gating networks were tested in-circuit using the diode check mode of the DVM, and they all appeared to be OK. Resistors were measured for proper resistance values, and all were within spec. So, attention was turned to the transistors. A shorted transistor could easily drag down the output(s) of the timing chain flip flops.

Testing transistors in-circuit can be a hit or miss proposition. It is much better to remove the transistors from the circuit, and test them individually. The difficulty with this is that the Wang Logiblocs were hand-assembled. At the time this 370 was manufactured (1969), automated component insertion equipment was very rare. Thus, components were manually inserted into the circuit boards, with the leads bent over on the wire side of the circuit boards to temporarily secure the parts on the board. Once all of the components were installed, the boards were flow-soldered. This makes component removal a little difficult, because with the component leads bent over, the solder needs to be removed, then the leads unbent carefully, and then any residual solder removed while the component is very carefully extracted from the circuit board. A high quality temperature controlled soldering iron, combined with a vacuum solder-removal system makes it possible to remote components, but even with these tools, component extraction is still tedious and time-consuming.

It was decided to remove the seven transistors involved in the timing chain decoding logic and test each of the transistors using a transistor tester.

All seven transistors (RCA-made 2N404 Germanium PNP transistors) were carefully removed from the circuit board, and each was tested. As it turned out, one transistor was found to be bad. It had a short between collector and base that applied -11V to the output of the diode gating network. This served to drag the output of the T1 timing chain flip flop down to near -11V. This was certainly the reason why the timing chain flip flops weren’t running properly. The defective transistor was replaced with a known-good one (the museum has a stock of spare parts for the Wang 300-Series calculators) and all of the transistors re-soldered back in place on the 571 board.

The 571 board was replaced in the backplane, and the scope set up to monitor both the master clock signal, along with the T1, T2, and T3 timing chain flip flop outputs. Power was applied, and low and behold, all three flip flops were flipping and flopping exactly as they should be. To double check, the outputs of each of the logic networks that decode the various states of the timing chain flip flops into timing phases that sequence the operations of the 370 were tested, and each output was as-expected, depending on the state of the three timing chain flip flops at any given point in time.

Now that the timing chain was running properly, it was time to see if programming operations would function properly without hanging the 370.

The 371 Card Reader was connected up to the 370, and the 370 plugged into a Wang 360E electronics package. When powered up, the display showed “+0.000000000” as expected. A program card had been prepared, punched with codes to perform keypresses of [1], [2], [3], followed by a STOP instruction. This program, if it ran, should result in “+123.0000000” being shown on the display.

The card was loaded into the reader, the [PRIME] key pressed to initialize the calculator and the 370, and then the [CONTINUE] key was pressed, which should start the program executing. Nothing happened. The display still read “+0.000000000”. Pressing the [DISP PROG] key showed that the program counter was at “00”, and the step at that location was as it should be. It appeared that the program did not run, as if it had, the program counter should have been something other than “00”. The [DISP PROG] key was released, and the display reverted back to “+0.000000000” as expected. Then the [STEP] key was pressed (with no apparent response by the machine), followed by again holding the [DISP PROG] key. The machine still said that the program counter was still at “00”. If the STEP function worked properly, I would have expected the program counter to have incremented to step “01”. It didn’t.

It appeared that some problems still exist. Just out of curiosity, the [PRIME] key was pressed, followed by the [7] key, just to make sure that the 370 was still talking to the electronics package. Nothing happened. A number of different key-presses were attempted, and none of them had any effect – the display just kept reading “+0.000000000”. Pressing the [PRIME] key resulted only in a slight dimming of the Nixie tubes – not a good sign. I powered everything down and powered it back up, and tried using the 370 as a plain old calculator keyboard/display unit — functionality which was known to work in the past. Sadly, there was no response to any keypresses on the 370. It appears that in the process of trying to figure out what was up with the timing circuitry, some other problems have cropped up.

Just to make sure that the 360E electronics package didn’t have a problem, a 360K keyboard unit was connected up to it, and it worked fine. So, the problem is definitely something new that has developed with the 370. It seems that I had made one step forward then taken two steps back.

This isn’t the first time that such a situation has occurred when working with old electronics like this. With equipment that is nearing 40 years old, there is much potential for problems. Sometimes just the physical shock of unplugging circuit boards can cause components that were marginal to fail completely. Sometimes no matter how carefully old circuit boards are manipulated, just the act of moving them can create other types of non-component-related problems such as solder joints that were perhaps weak to begin with suddenly failing. Such things are a simple fact of life when it comes to working with electronics that are this old.

While this is a bit of a setback, it isn’t a disaster. It just means that it’s going to take a little more digging to get to the bottom of the problems that this Wang 370 has. Of course, I will make update postings here as time presents itself to do more troubleshooting.

06-Feb-09 – More Busicom 161

February 6, 2009

The Busicom 161 calculator chassis donated to the Old Calculator Museum arrived Tuesday (2/3) morning. The box it was packed in looked a slight bit worse for the wear due to handling during shipping, but structurally, the box looked OK.

The machine was double boxed, which is one of the best ways to ship old calculators (the best way being custom-made conformal foam packing). The machine was cushioned by styrofoam packing “peanuts”, another good thing, however, it’s usually a good idea to first seal the machine in some kind of bag (preferably an anti-static bag) to keep the packing material from working its way into every nook and cranny — especially in a machine like this that is a bare chassis, without the cabinet. It took about 1/2 hour with long handled tweezers to pick all of the packing material out from between circuit boards, under the keyboard, and in various other cavities in the machine.

The first order of business, after harvesting the peanurs, was to give the machine a complete visual inspection once all of the packing material was removed. It was noted that one of the discrete neon lamps that are positioned between the Nixie tubes as decimal point indicators was missing. The wires for the lamp were sticking out of the circuit board, but the lamp itself was missing. Referring to the photograph of the machine placed in the eBay auction showed that the lamp wasn’t there in the auction posting, so it wasn’t missing as a result of shipping damage. This isn’t a big deal, as it likely can be replaced. The chassis was turned upside-down, and the glass neon tube fell out from inside the machine. Apparently somewhere along the line, the indicator was broken, probably as a result of improper handling without the cabinet in place, and it fell down inside the machine.

The next step was to very carefully pull out each of the 41 logic circuit boards. There are 42 logic circuit boards in the machine, but one of them isn’t removable. It contains the Mitsubishi-made 16×16 magnetic core array, and it is hard-wired into the backplane. Why this board is hard-wired is beyond me, – many machines of similar design use plug-in core arrays. It is interesting to note that the IME 84, upon which it appears the Busicon 161 was patterned, also has a fixed circuit board for the core memory array. Anyway, all of the logic boards were individually carefully withdrawn from their backplane connectors.

As discussed in the original posting about the Busicom 161, the museum’s existing machine has severe problems with the edge connector sockets losing their structural integrity. It was strongly hoped that this chassis didn’t share the same problem. Unfortunately, as the circuit boards were removed, it was found that of the 41 sockets, six of them suffer the same kind of problem.

The problem manifests itself by cracks developing in the plastic-like material that the socket contacts are encased in. The socket contacts are gold-plated, and look somewhat like a “Y”, with the open part of the “Y” being where the card edge connector is inserted. Each connector has 22 of these contacts. Once the plastic material cracks sufficiently, the tension that holds the contacts in place is released causing the contacts to become mis-positioned, and also to lose the spring tension that keeps them in contact with the gold-plated fingers on the wire side of the logic circuit board.

Given the problems wtih the backplane, it was not safe to try to power up the machine with the circuit boards in place. But, it was possible to check out the power supply. The damaged backplane connectors were carefully inspected to make sure that none of the contacts were shorted, so that when the machine is powered up without the circuit boards, there’s no chance of short circuits. The Nixie tube display subassembly, and the keyboard subassembly were removed. Both subassemblies connect into the backplane wiring with high-quality connectors, allowing these units to be easily removed and serviced. Unfortunately, the power supply is hard-wired into the backplane, meaning that some disassembly is required in order to look at the power supply circuit board. Once things were taken apart enough, the power supply board was found to conveniently have nomenclature on it identifying the various voltages. The power supply makes +5, -12, and -5 volts for logic supplies, and +85 and -85 Volts for powering the Nixie tube displays. The power switch for the machine is located in the keyboard assembly, and thus the wiring for the power switch had to be traced and a jumper fashioned to plug into the socket that the keyboard plugs into, in order to simulate the power switch being “on”. Three digital voltmeters were connected up to the power supply, and the power cord was plugged into a Variac, and the voltage slowly ramped up. There were no signs of any trauma as the mains voltage was ramped up to 50%, then slowly up to 75%. The digital voltmeters started to register voltages. Once the mains voltage was at 100%, the +5V supply read +5.31V, the -12V supply was at -13.21V, and the -5V supply was at -5.89V. The voltages were all a little higher than expected, but this is liekly because there was no load on any of the power supply voltages. The Variac was turned off, and two of the DVM’s connected up to the +85 and -85V Nixie tube power supplies, and the machine powered back up again. The +85V supply was running at almost 89V, and the -85V supply was running at just over -90V. These voltages aren’t as critical as the logic supplies, and aren’t actively regulated. Transformer windings are simply rectified and filtered, so some variance in the output voltages is to be expected. Lastly, the machine was again powered off, and the oscilloscope connected up to the logic supplies to measure ripple, to make sure the power supply filter capacitors were OK. All of the logic supply voltages had only slight (1-2 millivolts) of ripple, all within safe boundaries. With all of these measurements performed, the power supply of the machine seems to be in good health after all these years.

Speaking of years, this 161 appears to have been made at very close to the same time as the original 161 in the museum. Transistors are all coded with dates in the range of the 2nd week in 1969 to the 5th week in 1969, while the original 161 has date codes that are just a few weeks later, with the latest date codes listed being in the 6th week in 1969. In a rather silly move, Busicom put the serial number tag on the back surface of the upper part of the cabinet. The upper part of the cabinet on the recently donated machine was missing, thus, there’s no way to identify the serial number on this machine. While disassembling the machine, I looked high and low for any hints of a serial number stamped or written in other locations within the chassis, but none was found. This is rather unusual given the price of machines of this vintage (frequently $1000 or more, which was a lot of money in 1969), many manufacturers put the serial number on a fixed part of the machine that was not easily removable, and also had markings inside the chassis that provided secondary identification of the serial number to aid in identifying a machine if it was lost/stolen.

It is going to take some time to figure out a stragegy to replace the edge connector sockets that are bad. Experience trying this with the other Busicom 161 proved to be futile. That time, the connectors were replaced with the backplane in place. This involved very carefully separating the dense wiring to clear it away from around a failed edge connector socket (horribly difficult because the backplane wiring is very tightly laced into a big bundle of wire), carefully desoldering the wires to the bad connector, putting in a new connector, and then soldering the wires back to the new connector. This proved to be nearly impossible due to the density of the backplane wiring. A different approach is going to be needed to replace the faulty connectors on this machine. Fortunately, the connectors used are standard 0.156-spacing 22-pin sockets, easily available through any electronics supply outlet. The edge connector sockets in the 161 are held in position by rectangular holes in the bottom of the circuit card guides that are screwed into the chassis. There are bosses on each end of the edge connector sockets with a hole through them that would allow the connectors to be screwed into a circuit board or chassis to hold them in place. The screw holes are not used in the 161, but these bosses fit into the rectangular holes on the circut board edge guides on each end of the connectors to hold each connector in place. If the card guides are removed from the chassis, this would free up the edge connectors to “float”, allowing the backplane to be worked on in a much easier fashion. The only support for the edge connector sockets at this point would be the backplane wiring itself. This is likely that strategy that will be used to try to safely replace the damaged sockets. The real difficulty with any means to try to replace the connectors is that the backplane wiring uses only minimally color-coded wire, and due to age, heat cycling, and other factors, the coloring on the wire insulation is sometimes very difficult to make out. There’s no schematic or service documentation that I’ve run across for the 161 (if anyone knows of any such documentation, I’d love to hear from you), so it means that very careful observation and documentation of the wiring will have to be done. This will rquire a lot of digital photography at close-quarters, a lot of time with bright lighting and a magnifying glass, and meticulous note-taking. Keeping all of the wiring sorted out to assure that it all goes back together again with the correct connections is going to be absolutely critical. No room for any errors here.

I need to get hands on replacement connectors, which is something I hope to do sometime soon. Once I have them in hand, and have been able to take things apart enough that I can test my method for repair, I’ll make a new post here letting everyone know how its going. In the meantime, I plan on taking the original machine and taking photos of it (though it’s certainly not operational), and begin the process of creating a museum exhibit for the Busicom 161. The goal of the Old Calculator Museum is to have fully operational machines, but for the time being, the Busicom 161 exhibit, when I put it online, will be one of the few exhibits where the machine shown isn’t operational. But, over time, I hope to be able to get a fully-operational machine. Betweent he two machines, there are plenty of spare parts that an operational machine can be made, assuming I can get through the backplane repairs without causing more problems or, worse yet, irreparable damage.

Thanks for reading.

29-Jan-09: Wang 360SE

January 29, 2009

Today I had some time to look into the Wang 360SE that was recently donated to the museum.

Visual inspection was the first order of business.  First, the cover over the backplane was removed so that a complete visual inspection of the backplane and power supply circuit board could be performed.  The backplane in the 360SE is a hard-wired affair.  Wang used a unique method for wiring the backplanes on these machines that used special edge connector sockets with long rectangular tail pins on the backside that special clips attach to.  The clips are soldered to the individual wires in the backplane wiring harness.  The clips visciosly grab the tails on the edge connector sockets to provide connectivity between the various edge connector sockets.  Intuitively, this method doesn’t seem like it’d be very good in terms of long-term reliability, but amazingly, it seems to work very well.  Even though the edge connector tails and the clips are made from what appears to be a tin alloy, the connectivity this system provides seems to be very relaible, even after 40 years.

Looking over the backplane carefully showed no signs of any loose connections or broken wires.  The power supply circuit board looked as if some of the components (mainly rectifier diodes) had been replaced at some time during the machine’s life.  The machine’s service tag did not indicate anything of these repairs, so it is likely that these repairs were not done by a Wang service technician.

The backplane cover was replaced, and the cover over the Logiblocs was then removed.  All of the Logiblocs were then carefully pulled from the sockets so that all of the edge connector socket fingers could be inspected, as well as checking the edge connector fingers on the Logiblocs for corrosion.  The edge connectors were all in good shape, and there was only light corrosion on the Logibloc fingers, which were all cleaned with a contact cleaning solution.  Each Logiblock was also inspected to make sure there were no sign of obvious problems, and all looked good.  The core memory board was inspected under a magnifying glass to check for any broken wires in the core array, and no problems were found.

The power supply transformer and large computer-grade capacitors were visually inspected, and looked good.  The line voltage fuse was checked, and it was found to be good.  Without power connected, an ohmmeter was placed across the power supply hot and neutral prongs on the plug, and the power switch turned on to check for too little resistance, which could indicate a shorted line filter device, or the mains winding in the transformer. The ommeter showed about the same resistance reading as the known good Wang 360SE already in the museum.

The power supply of the 360SE generates +11V and -11V, along with 230V for drive of the Nixie tubes on the keyboard/display units.  With all of the Logiblocs removed, it was possible to power up the machine and check the power supply voltages.  The 360SE electronics package was plugged into a Variac, and the voltage very slowly raised up to full line voltage, while monitoring the +11 and -11V supplies using two digital voltmeters.  It became apparent as the line voltage neared 50% that the power supply wasn’t doing anything.  The +11V and -11V DVM’s showed +0.000 on their displays.  As I ramped the voltage up to full line voltage, there still was no output at all on either of the logic power supplies.   Clearly, there’s something amiss with the power supply, that will require more digging to sort out.

There are two thermally activated "pop out" circuit breakers that provide protection for the +11V and -11V supplies.  The first thing to do was check them.  Visually, they weren’t popped.  They were both checked wtih an ohmmeter, and had full continuity.  Unfortuntately, the problem was not going to have a simple solution.

I ran out of time to work on the machine any further during this session.  The next step will be to check the transformer secondary voltages with power applied to see if the transformer is working properly.  If a problem is found with the transformer, finding a replacement is going to be difficult.  Any replacement would have to have the proper primary and secondary windings, as well as be very close to the size of the original, as the transformer is pretty tightly packed in the chassis.  If the transformer proves to be OK, then the problem is likely somewhere in the circuitry that takes the AC voltages out of the transformer, rectifies it to DC, filters it, and then regulates it to the proper supply voltages.

I’ll write about further digging into this in a future blog entry.

28-Jan-09: Busicom 161

January 28, 2009

Apologies for delays in posting to the blog — things have been somewhat chaotic around here.

Some more work has been done on the Wang 370/371, but it needs to be written up and posted.  Hopefully I’ll get to this soon.

This posting is about a recent development relating to a Busicom 161 electronic calculator. For background, the Busicom 161, introduced in July of 1966, is the first electronic calculator sold by Japanese calculator manufacturer Nippon Calculating Machine Co. (NCM).  NCM had made a big market for itself in the Japanese market by making wonderfully compact and reliable hand-operated mechanical calculators that could replace the soroban (abacus).  With the advent of the electronic calculators, first by Sumlock Comptometer/Bell Punch (the Anita C/VIII) , followed by others, NCM felt that their corner on the market for small mechanical calculators could be at risk.   As a result of this concern, NCM embarked on a program to develop an electronic calculator.  The Busicom 161 is the result of their efforts. NCM created a new business subsidiary called Busicom (Business Computer) that would be the trade named by which NCM would market their electronic calculators.

Rumor (not well substantiated at this point) is that the design of the Busicom 161 was based on information gleaned from reverse-engineering a calculator made by Italian calculator maker, IME (Industria Macchine Elettroniche), the IME 84.  The IME 84 was a brilliantly-designed machine, implemented with all-transistor logic, magnetic core memory for register storage, and Nixie tube display. There are claims that the IME 84 was the first electronic calculator to use magnetic core memory, but this assertion is incorrect, as the Mathatronics Mathatron calculator holds this historical distinction.

The Busicom 161 may share the same architecture of the IME 84, but its implementation is much less sophisticated. The IME 84 has a much higher component density, with the entire machine housed in a compact, low-profile desktop package. The Busicom 161, in contrast, is comparatively huge. It takes up about the same amount of square inches of desk space, but it is much taller. The circuit boards in the 161 are very simplistic, using low-component density (the most complex boards have 20 transistors on them), with circuit traces only on the back side of the board, and single-sided edge connector fingers. The 161 uses a total of 42 circuit boards, arranged in three rows of 14 boards each, stacked vertically in the chassis, which is the reason why the 161 is so tall. The machine has a capacity of 16 digits, with fixed decimal of 0, 1, 2, 3, 6 or 9 digits behind the decimal point. The Nixie tubes display the digits zero through nine, and decimal points are indicated by discrete neon lamps situated between the Nixie tubes. The 161 has a single accumulator-style memory register, and one-key automatic square root. Transistors used in the Busicom 161 are made by Mitsubishi, using standard 2S-series silicon transistors.

NCM/Busicom holds a special place in history. In the late 1960’s, Busicom engineers had developed a design for a complex calculator chipset that could be configured to perform the functions of a large number of different calculator applications. Busicom contacted fledgling integrated circuit memory manufacturer Intel, to see if they could fabricate the chips that Busicom had designed. Intel’s engineers looked at the complex nature of the chipset, and decided that it would be more efficient to develop a small programmable computer on a chip that could be programmed to perform whatever operations a calculator designer required. Intel took this idea back to Busicom, and while Busicom management and engineers weren’t initially impressed by the idea, and instead pushed back at Intel to simply fabricate the chips as originally specified, Intel’s engineers had developed a breadboarded prototype of a simple calculator based on the idea, and this convinced Busicom that this may well become the future of electronic calcualtors. Busicom negotiated an exclusive contract with Intel to produce the programmable processor, which historically became known as the first commercial microprocessor, the Intel 4004. Intel also developed support chips that provided read-only memory, random access memory, and peripheral interfacing chips. Busicom and Intel jointly developed a business-oriented desktop printing calculator that Busicom sold as the model 141-PF — the world’s first microprocessor-controlled calculator, introduced in October, 1971. Sadly, the Japanese economy went into a recessionary period during the early 1970’s, and in spite of the technological triumph that Busicom 141-PF represented, NCM/Busicom started to suffer financial problems. Intel saw an opportunity to get out of the exclusive agreement with Busicom for the 4004 microprocessor and support chips, and a deal was negotiated to allow Intel to sell the microprocessor to other customers just a month after the 141-PF was introduced. This development led to Intel further developing its microprocessor business, leading to the Intel 8008(April, 1972), and then, the 8080(April, 1974), the microprocessor chip that truly ushered in the beginning of the personal computer revolution. By February, 1974, Busicom’s financial woes prompted it to file for bankruptcy. In November of ’74, NCM/Busicom ceased operations, making the company the first major Japanese calculator manufacturer to succumb to ongoing shakeup in the calculator industry that resulted in many calculator makers getting out of the calculator business, or going out of business altogether.

Fast-forward to more recent times. A while back, the Old Calculator Museum managed to acquire a complete Busicom 161. It has not yet been documented in the museum because the machine needs restoration before it can be exhibited. The main issue with the machine was that the edge connector sockets in the hand-wire backplane were disintegrating. It isn’t known if this is endemic to the material used in the connector sockets in the Busicom 161 in general, or if this is a malady suffered by this particular machine due to some kind of environmental conditions during the machine’s lifetime. Appropriate replacement sockets were found, and a number of the original sockets that were in the worst condition were replaced. This operation was extremely tedious as the wire density in the backplane is high. The power supply was checked out to be OK, and once the connectors were replaced, the machine was powered up, but alas, it doesn’t function properly. Since then, more edge connector sockets have started to fail, meaning yet more connector replacement must be performed.

Busicom 161 Backplane Wiring

Now, to the present. About a week ago, a frequent donor to, and good friend of the Old Calculator Museum, sent an EMail indicating that there was an interesting looking calculator chassis up for auction on eBay. I checked it out, and realized right away that it looked very familiar. The machine at auction was a complete Busicom 161, minus it’s cabinet. In further EMail dialog, this friend indicated that they would be willing to bid to win the calculator, and then donate it to the Old Calculator Museum. The bidding went well, and now the Busicom 161 chassis is on its way to the museum.

It is hoped that the soon to be received chassis will have backplane connectors that are in good shape. The goal will be to try to get a fully operational machine, either by getting the chassis up and running, or by mixing and matching parts to get a working machine going.

Watch this blog for more information on this project.