Arduino - DIY Electronics for the 21st Century?

Over the past year or two, it has felt like you can't turn a page in a tech magazine, or read a web page about electronics without some reference to the Arduino. Somehow it seems to have moved from serious "difficult" electronics, into an everyday commodity.

Thus far, I had resisted the Arduino's allure. I don't have any experience with Atmega processors, my usual preference is for one of the Microchip PIC families or, if more power is needed, an ARM cored device. But how could I give an opinion without owning one and having a play around with it? I was impatient as usual, and the people at Farnell / Element-14 had one sitting on my desk within 24 hours. Excellent.

The Arduino Uno

I will go into more details later, but here is a quick rundown.

The Arduino Uno is a totally open source embedded development board, based around the Atmel Atmega328. Other "flavours" of Arduino are available, usually based around other Atmega chips. Arduino isn't just limited to the hardware, however. It also covers the development environment which, to my mind, is the crucial factor in it's success.

The Arduino Development Environment
(Click for larger image)

As you can see from the screen grab above, this isn't Microsoft Visual Studio. Thank goodness. Simple and clean with syntax highlighting. This is why Arduino has taken off.

The Uno itself measures just 53x69mm, and arrives in a simple cardboard box that looks more like a packet of cigarettes or condoms. No. Really. The accompanying leaflet covers the usual legal disclaimers and little more. It would be nice if it said "Congratulations on your new Arduino, now download your free development software from www.arduino.cc" or similar.

It is powered via the standard USB "B" socket, or via a jack socket. I find it odd that they haven't moved over to a mini or micro USB, but no great shakes. The general standard of construction is solid, as you might expect with a mature product, the CPU being a socketed 28-pin DIP/DIL device. This is so you can remove it after programming, or plug it into a breadboard. Or, I suppose, replace it if you toast it.

There is a HUGE amount of resources for the Arduino around the Internet. Almost too many. If you are interested in seeing what it can do, and how easy it is to use, then I recommend Jeremy Blum's YouTube series here.

I got mine from Farnell / Element-14, who stock a range of Arduinos and related gear.

The Arduino Uno I reviewed is available here http://uk.farnell.com/arduino/a000046/board-arduino-uno/dp/1848687

Arduino's home is at arduino.cc

John's Tronix Stuff tutorials here.


Additional: If anyone has any good Arduino tutorial sites they would like me to add, simply add a comment or drop me a line.

Tektronix DMM4020 Bench-top Digital Multi Meter - First Impressions

This is an initial overview of the Tektronix DMM4020  Bench-top Digital Multimeter.

This overview was originally written for Element-14 and is available here. 

http://uk.farnell.com/tektronix/dmm4020/multimeter-bench-5-5-digits/dp/1771901

http://www.tek.com/products/digital-multimeter/dmm4020/

Unit Price:    £528.00  

I must stress that this is just an initial overview.  The DMM4020  is very much a professional piece of test equipment and needs to be used properly in a work context for some time before I can give a thorough in-depth review. Nevertheless, in the short time that I have had it, I have already learned more than enough to give a good overview.

A few month ago, I had considered that a good bench meter should really go on my list of test gear. Less than a week after its arrival, I wonder how on earth I managed without one. After all, hand-held multimeters are really good now and - it has to be said - more than good enough for most work. So why has a bench meter already earned its place in my lab?  Read on…

The meter arrived in sturdy double-layer manufacturer’s box measuring 9”x12”x17”. Inside is a pair of vacuum formed foam blocks which sandwich the meter and provided good impact protection on its journey here. It is the sort of packaging that is worth keeping for storage, should you need to move it around or keep it safe.

Unless you have a huge bench or a permanent place in a rack, then this meter does take up quite a bit of space, being 9 inches wide and 13 inches front-to-back (although it is tiny in comparison to the high end calibration lab stuff). Traditionally though, bench gear like this does appreciate being left switched on permanently, to allow the temperatures to stabilise, minimise thermal cycles and prevent any moisture affecting components as the lab cools down over night. Unfortunately the DMM4020  has a fluorescent display, which has a tendency to fade when left on for extended periods (years). I have not yet discovered a way to turn the display off whilst keeping the electronics running. There is a “soft” power button on the front panel which may well perform a similar function. That is definitely something to investigate. Otherwise, though, the VFD is bright, sharp and fast to react, probably better than LCD could give.

However, this is jumping ahead slightly. The very first thing that I saw – a printed manual. Yes folks, real paper, with print on it. Spiral bound. Hallelujah! Only 26 pages of it are in English (the rest is Japanese and Chinese). It is only a “Safety And Installation” Manual, but it covers the main functions and accuracy tables. The full User Manual is 110 pages but unfortunately only available in PDF format. I will go more into the contents of this manual in the full review. The S&I manual states that power consumption averages  10 Watts, with a maximum of 15 Watts. Each side of the case is  plentifully supplied with ventilation holes, and having left the DMM4020   on for 6 hours, the temperature stabilised just above ambient. It runs  very cool indeed for mains powered gear.

Caution!

There are two things to watch out for before you start. Most importantly, the DMM4020  uses a conventional transformer power supply which is supplied configured for 110V.

It takes until page 10 of the Installation Guide before it mentions line voltage selection. I imagine almost all users will know to check this first, but in a world where people are increasingly used to switched mode power supplies that take 100-240V without configuration, a caution sticker would probably be wise. The actual method of voltage selection is a bit odd but nevertheless functional; You unclip and remove a module which has the mains fuse and a plastic “spider” inside, which is rotated to suit 100, 120, 220 or 240V and re-inserted. Despite having a mains transformer, the unit only weighs a modest 2.1kg

Secondly, the supplied mains cable has a US standard plug. This is not a problem though, as the connector is a standard IEC “kettle lead” and most labs have plenty of those hanging around! The DMM4020  does have a set of stand-off feet moulded into the rear of the case, which allows it to be operated vertically rather than in the conventional horizontal manner.  Unfortunately the supplied mains lead is a “straight through” rather than a 90 degree elbow, and so if you try to stand the meter upright, whether against the floor, desk or slotted into a rack, it sits on the cable rather than the feet, and so is unstable. Note to Tektronix : Supply a 90 degree "Elbow" power lead please!

One thing which is really good to see – a proper mains on/off switch mounted next to the power connector. So far as I can see from looking through the ventilation holes, this is a proper switch which isolates all internal components.

Construction

As you can see from the photo, the DM4020 comes in Tektronix corporate colour. That familiar grey-blue colour which is so often seen around labs. The main body is pressed alloy construction, with plastic front panel. The front and rear both have flexible plastic/rubber protective “boots” which can be removed for rack mounting. As usual with this sort of equipment, there is a tilting bail which can be positioned in a number of angles, used as a carrying handle, or removed entirely. The HRC fuses are of the high quality you would expect, and are accessible by removing a small metal panel underneath the unit. A small plastic box covers the fuses themselves, presumably for insulation and blast containment.  They don’t seem as well protected as they are in hand-held meters.

Internally

I don’t intend to take the DMM4020  apart, not least because that would entail breaking the calibration seals, which I am loathe to do. Fortunately, however, you can get a pretty good view of the insides just by looking through the ventilation slots. This is very much a unit for a clean lab and not a dusty shop floor which would risk contaminating the sensitive electronics in no time.

Visible in the middle off the board is the heated precision voltage reference, clearly labelled LM399H with a National Semiconductor logo. A well known and well respected precision voltage source, used in several meters in this market segment.  Interesting that they didn’t choose an LM199 or LM299 which seem to be 2% initial tolerance versus the LM399’s 5%, although it has to be said that after calibration there is little difference. I suspect that putting the unit into standby from the front panel will keep the heater running inside the voltage reference whilst powering down the display and processor. This would seem an ideal compromise.

In use.

As you can see from the front panel, the Tektronix DMM4020  is a 5 ½ digit unit, with separate connections for low (200mA) and high current (10A) ranges. It is also capable of full 4-wire resistance measurement, although only a pair of Tek TL710 conventional probes are supplied. Supplied probes are usually low budget affairs, but these are really nice sharp Cat III/Cat IV 10A probes with finger shields. However - no ground clip is provided! This is definitely an oversight in a meter of this stature.

One feature I will certainly be looking at is the ability to take two measurements at the same time, or sequentially. Some meters can perform functions such as AC voltage + Frequency, but not many can perform current + voltage measurements together, or DC+AC, such as might be used to monitor power supply ripple.

You will note that it does not measure inductance or capacitance. I guess at this end of the market you would be expected to purchase a separate LCR meter.

Performance

These are the easiest to quantify in hard numbers. All this data is copied from the official (copious) Tektronix information, boiled down into the main points. I will go into more depth in the main review:

Measurement Speed

The DMM2040 can measure at 2.5, 20 or 100 samples per second. Normally 2.5 is perfectly sufficient, and 20 cannot be distinguished by human eye. However, this is good for capturing short transition events, or for high speed logging via the computer link. In the faster two modes, however, precision is truncated by one digit.

DC Voltage

Maximum input: 1000V
Input bias current: <30pA @ 25C
Input impedance: >10G Ohms (200mV and 2V ranges)  10M Ohms (20/200/1000V ranges)
Resolution on 200mV scale: 1uV
Accuracy:    +0.01% of reading + 0.003% of range

 

AC Voltage (True RMS)

Maximum input: 1000V peak, 750V RMS.
Accuracy (all ranges 45Hz – 20kHz): 0.15% of reading + 0.05% of range

 

DC Current

Input protection: 11A/1000V and 440mA/1000V fuses

Shunt resistance: 0.01 Ohms (2A and 10A ranges)
                           1 Ohm (20mA and 200mA)

Resolution:         200uA scale: 1nA (yes, that’s 1 nanoAmp)

Accuracy:           typ. 2mA scale 0.015% of reading + 0.005% of range

 

AC Current:

AC Filter Bandwidth: 20Hz – 100kHz
Maximum Crest Factor 3:1 at full scale
Resolution:  20mA scale: 0.1uA (100nA)

Accuracy:  Typ. 200mA scale, 45Hz-2kHz: 0.25% of reading + 0.05% of range.

 

Resistance

Specification for 4-wire function or 2-wire with REL (relative measurement)
Input protection: 1000V on all ranges
Resolution:         200 Ohm scale :  0.001 Ohm (1 milli-Ohm)

Frequency:

Range: 20Hz – 1MHz, for input >100mV
Accuracy: 0.01%

Continuity:

Threshold: 20 Ohms
Test current: 1mA

Unseen performance

So much for the book data. With less than a week’s use, it is safe to say that I haven’t even scratched the surface on what the DMM4020  can do, but I have found some very nice functionality that most users just wouldn’t notice unless they were looking for. Specifically:

Diode test.

Most diode test functions only work at 1-1.5V, enough to test ordinary signal diodes, but not enough to test LEDs. The DMM4020  reads up to 1.9999V and drives up to 0.8mA, sufficient for the LED to light quite brightly. In theory this is only enough for red /yellow/green LEDs, but in practise the unit will illuminate blue and white LEDs also, which I was not expecting, although it will not give a voltage measurement for these.

Zero-burden Microammeter.

Most engineers will be aware that the usual way of measuring current is to insert a small resistance into the circuit and measure the voltage drop across it. At low currents this can be quite a high resistance, leading to a “burden” voltage drop which is unacceptable and may even upset the circuit under test.

The correct way to do this is with a transimpedance amplifier which provides almost no voltage drop, but can only realistically be performed at low current levels. It is quite a complicated thing to get right in a design and, as a result, is only usually seen in expensive dedicated microammeters. The Tektronix DM4020 is the only meter that I know of (this side of £1000 anyway)  which uses this preferred method for measurement. If you often measure low currents, this feature alone may be worth the price of the meter.

Relay Range Switching.

In order to switch in appropriate shunts and multipliers, the DMM4020  uses proper electromechanical relays rather than silicon switches. This slows down auto ranging, but not unacceptably so. Manual override is always available and is probably preferred in most cases. Relay switching is by far the best method in equipment where you are looking for measurement performance and have the luxury of a large PCB real estate and a mains power supply.

“Other Stuff”

The supplied LabView software is a little clunky to install (and partially deactivates after a preview period) but does work pretty well. I am no LabView expert, but I can see how relatively easy it is to automate tasks if you are working in a production environment. This is definitely one thing I will be looking more closely at. Simply logging data in ASCII format to a text file is very handy indeed.

In order to connect the DMM4020  to the outside world, it is fitted with a standard RS232 port at the rear. Tektronix thoughtfully provide an RS232-to-USB adaptor, with a good 2M of cable. This seems to be based on an FTDI chip, which in my experience has proven most reliable in this sort of role. Windows 7 picked it up straight away and downloaded drivers via Windows Update.

Conclusion

So there we are. Four days use and a “quick” look that is already several pages long. That gives you an idea about what sort of machine the Tektronix DMM4020  is, I hope that I have at least been able to give a taste of what this machine can do. I hope to have a much more in-depth review up in a few weeks, after it has had some use in a real world situation. One of the things I have lined up is the development of my LCR meter project. Having a meter this accurate will help immensely.

A Request

I want to shoot some video of the DMM4020  in action if I can. At the moment I only have a webcam and a cheap compact camera that will shoot video, so I am looking to buy myself a reasonable 720 or 1080 digital video camera. Does anyone have any recommendations? I don’t want to spend more than maybe £150 or so, it doesn’t need to be a fantastic spec. Thanks!

Additional: Farnell / Element-14 tell me that UK purchasers will have their meter pre-configured for UK 240V power.

HP-15C now in Stock at HP! No it isn't! Yes it is ! No it isn't!

Well, the HP-15C finally made it to market, and promptly sold out within a few hours. So quickly, in fact, that I didn't even get a chance to post it here before they had all gone. From the look of Ebay, many seem to be bought by speculators.

Anyway, they are back on sale at HP's online store. Oh wait... No they aren't. This time the stock lasted about half a day. All I can say is - keep an eye out for when they restock! My guess is that if they keep selling this quickly, then the Limited Edition won't be quite so limited.

Amazon.com look to have them in stock. 4 left at the time of writing, listed at a mere $119:99. $20 more than the official HP shop, albeit Amazon have free shipping. Can we say "gouging"? I thought so. Still, it is cheaper than Ebay.

I don't think I will be buying one, I find the missing binary / hex modes too useful. Any chance of the HP-16C? Potential purchasers might like to be aware that the build quality is typical Kinpo Electronics rather than classic Hewlett Packard.

A PCB CAD Refresher Course

At one time it felt like I was destined to be a PCB designer, churning out design after design for someone else's work. Now this is a very worthwhile and skilled job, but it wasn't for me, and so it is only occasionally that I get to design PCBs now. Unfortunately that means that I tend to forget work-flows, and fiddly little quirks and details. Come to think of it, I tend to forget some pretty big details too! When you have let muscle memory get on with things, it can be daunting when you come back to your CAD software.

I have a fair few notes which I have written up over the years, and I was even considering recording a video. This started me wondering what YouTube might have to offer. Altium have done a load of videos (hosted on their own site), but I have to say they aren't very helpful. At best they are rather "corporate". Anyway, to cut a long story short, I found these YouTube videos. They are clearly recorded by someone who knows what he is doing, and aimed at the more introductory end, but are very much worth watching if you need a quick refresher.


All these videos relate to Altium Designer, and are best viewed full screen. Videos recorded by http://www.youtube.com/user/elektroniskorg

1. Schematic capture and PCB layout (Part 1)

2.Schematic capture and PCB layout (Part 2)

3. Creating a Component Library

 
4. Navigating Designs

5. Working with Vias and Multiple Layers

6. Copper Planes and Pours

Advanced Calculations

(Or how 1989 - 2011 = 15+30+34+41 )

Thanks to Make Magazine Blog for mentioning my article on calculators (see Difficult Calculations ). It seems that I am not alone in my calculator geekery. Page views shot up by a factor of 100x in a couple of hours!

Inevitably though, no sooner had I written the article than things started to move on. It looks like Hewlett Packard aren't totally devoid of sense after all. Thanks to Dave Jones of the EEVBlog for pointing me in the direction of this:

Yes, this is from the real Hewlett Packard web site. This is a screenshot of the Google cache (see here) of HP's Singapore web site. (Screenshotted just in case the cache gets overwritten) Similar pages were on other nations HP sites too, including the Indian version. I checked, and it all looks legitimate and not a spoof. At the time of writing, HP still hosts a photograph of the calculator in question, an HP-15C:

HP-15C Limited Edition

Investigations by the forum members at the HP Museum site have revealed that the "HP-15C Limited Edition" will shortly be on sale in Japan. No information is available as to whether they will be shipping them in other countries.If they do appear in the UK, then one is going straight on my shopping list.

It looks like a pretty close copy of the original, but the brushed aluminium bezel around the display has been replaced with what looks like white plastic, and the printing somehow looks less crisp. My guess is that Kinpo have been brought in once again by HP, and rather than simply producing a copy of the original, they have re-engineered it to maximise cost savings. Something which has rather back-fired on them in the past. As it stands, the (still in production) HP-12C internals have been converted to an ARM processor based system for some time, so a new version of the 15C and 16C should be straight forward.

Back in the 80s, the HP-15C cost $135. It looks like the new version will sell for an RRP of $129. That is fine in the US, the land of discounts and coupons, but I suspect it will come out at £129 here in the UK after taxes. Given that the HP-15C is based the same hardware used by the HP-12C ($70) then it starts to look a bit expensive. It is a shame that they didn't go the extra mile and produce the HP-16C too, which adds binary and hexadecimal functionality.

The WP-34S

It looks like the HP-12C re-purposing project (that's the polite term for hacking now) has stalled (see here) but the project to investigate the potential of the HP-20B and HP-30B business calculators seems to have moved onwards very quickly indeed (see here), enabling vastly more functionality, based around the HP-42S core software, but very much expanded upon. In fact, it does so much more, that the developers have had to print a whole new set of key legends:

Original HP-30b

Modified with WP-34SFirmware and key legends

Yes, these are the same calculator. I do wonder just how robust the stickers are, but reports seem generally favourable. A complete reprogrammed calculator + overlays is on sale at £76:98 / €84:68.  The firmware manual / user guide is available here.

Do you know what I love about it though? It has markings on the keys - and this is the important bit - I don't know what they all mean. Seriously, I have a row of letters after my name, I have been doing engineering maths for decades, but yet there is stuff in there that is a mystery to me. Sure, it is statistical stuff that I will never need, but that doesn't matter, it means someone is finally adding new functionality to calculators. It makes me feel a bit like when I was a kid with my nose pressed against the window of the glass cabinet with all those mystical electronic boxes inside.

So that is 15, 30, and 34 dealt with (see the blog title), how about 41?

Well, processor designer Monte J. Dalrymple has reverse engineered the HP-41C, and then created an improved version of it on an FPGA. I mean - seriously - it doesn't get much more hardcore than that does it?

Lots more information here on Monte's site. 

The thing is, all the essential hardware is on an FPGA. It is a relatively (and I use the term recklessly) easy job to hook up your own LCD and keypad, and you have your own HP-41C clone. All it needs is a millionaire willing to stump up enough money to make moulds for the enclosure. Some things have simply got to be done.

Suddenly, the world of calculators just got more interesting.

Hewlett-Packard Calculator Timeline

As part of my previous blog post on calculators, I had started to draw up a graphical representation of calculator evolution. My intention was to include TI, Sharp, Casio etc (hence the timeline starting at 1960) but considering this subset of HP calculators took several hours, I decided a full comparison probably wasn't worth the effort. Given the popularity of the previous item, I thought some people may be interested. It doesn't include all HP calculators by any means, finishing with the HP-48S.

Hewlett-Packard Calculator Timeline

Difficult Calculations

I suspect I was part of the first generation to have been brought up with “pocket” calculators (“pocket” to distinguish them from desktop mechanical calculators the size of a bread bin). I vaguely remember seeing them in my dad’s electronics magazines, sometime around 1979. One Christmas around then, my dad was bought one which has a fluorescent blue/green display which really looked super high-tech, and is still a really pleasing design. Although it was only a classic four-function machine (add, subtract, multiply, divide) I really coveted it, but it was couple of years before I got my own calc. 

Late 1970s Vintage LED Calculator
(Similar to mine)

I remember going to one of the electronics exhibitions that the magazines helped organise – possibly “Breadboard ’79” – where a stall was selling classic red-LED calculators for £2:99. Not only did it have the standard four functions, but a memory too. Wow, that was practically a computer! Other than the 7-segment, 8-digit display, the thing I remember most about it was the clicky keys. Noisy, but really good tactile feedback and, even on a super cheap calculator, it gave a feeling of confidence and precision. The 9V PP3 battery didn’t last more than maybe 10 hours, but it was long enough.

Of course the first thing I did when I got it home was to release the plastic moulded latches (no screws holding the case together) and take it apart. I was disappointed to find it had just one chip, and some convex metallic pads mounted directly on the PCB to act as switches. I felt ripped off that there weren’t half a dozen chips and proper switches, but it was all highly engineered compared with today’s products.

It was maybe a couple of years later, when I had moved up to the “big” school, that I discovered my form teacher had a programmable calculator. Woah! I had read about programmable calculators in magazines like PCW and Computing, and I had seen them locked away in glass cases in Boots in Leeds (for some reason Boots the chemist always had better calculators than the electronics stores of the time) but I had never seen one close up before. From what I remember, I think it must have been a Hewlett Packard HP-67, but I never got to see it again. The teacher had left it on charge at the back of the classroom over lunchtime, and some idiot had switched it off while the teacher was out of the room . She never (probably quite rightly) trusted us again.

Retro Calculator Sexiness
 The HP67 programmable

 Time moved on, and a year or so later I had saved up enough money to buy myself a Casio fx-3600p. Liquid crystal displays had pushed out the power-hungry LED machines, and my trusty Casio looks just like an average calculator you would buy today. Indeed it is only recently that Casio only stopped production of this model. Incredibly, it is still running on the same battery it came with. If I hadn’t experienced it personally, I would have said a 30-year battery life was impossible, but there you are. On the back it quotes “DC 3V 0.00043W”, something modern manufacturers still have trouble approaching today. The fx-3600p is programmable, but with only a 38 step memory and no alpha characters it’s programmability is rather limited to say the least.

As with many kids of the time I had a Casio CA-90 calculator watch (with a built in game that was surprisingly popular with the non-geeks at break times), and then a CFX-20 scientific calculator watch. Geeky? Hell yes. It even has a dot-matrix display which tells you what scientific or conversion function you have selected. Bloody good watch though, and I still have the slightly posher version, the chrome CFX-200. For some reason, I never particularly liked the styling of the CFX-40/CFX-400 which added potentially useful binary, octal and hexadecimal functions, but a cheap looking touch keypad.

1983 Casio CFX-200 Scientific Calculator Watch
(on my hairy wrist.)

Casio's later CFX-400 model with touch keypad.
Note the hex/octal/binary and logic functions.

 Sadly, that was the end of the line as far as calculator watches went. Casio decided to make “memory bank” and TV remote control watches instead. You can still get calculator watches of course, but they don’t even have the abilities I had in my 1983 scientific machine.

It would be remiss of me if I didn't mention at this point, Dave Jones' programmable scientific calculator watch design. I think Dave would be the first to admit it isn't exactly stylish fashion jewellery, but it is a phenomenal bit of work. It even plays a game of chess for goodness sake! Just imagine what Casio or Seiko could do with a bit of willpower and a million dollars or so.

Eventually I did my A-levels and decided that, for Uni, I deserved a better calculator and bought a fearsomely expensive and highly desirable Casio graphing calculator, the fx-7000g. So desirable that it lasted nearly 6 months before being nicked, and I went back to my fx-3600p. In all honesty, the fx-7000g wasn’t a great machine. Sure it did graphs, but then I know what graphs of sine waves, X^2 and so on look like anyway. I did get it to plot Mandelbrot and Julia set fractals, but that took forever, and a 1-bit greyscale can never do them justice. The huge screen just made it look clunky. In hindsight, this is where calculator design started to drive up a blind alley.

Casio fx-7000G Graphing Calculator

 

The temptation didn’t last long though, and a friend of mine had a Hewlett-Packard HP-28C. Properly programmable with a real programming language, small bitmapped display, alpha-numeric keys, hex/octal/binary, arrays, complex numbers and, most importantly, it had proper clicky keys and operated using the mystical Reverse Polish Notation – RPN. The absolute pinnacle of the calculator world. I spent a huge chunk of my first term’s grant on the 28C’s faster and more capacious offspring, the 28S. Thanks to the RPN, people only ever borrowed it once, and it never got stolen. It was worth every penny, HP had a track record of making well engineered calculators for people who use them every day. Calculators for engineers and scientists, not calculators for 14 year olds.

My Hewlett Packard HP-28S and Casio fx-3600P Programmable Calculators
(with obligatory schoolboy humour)

I still have both the fx-3600p and HP-28S, but more importantly though, I still regularly use them. The Casio needs it’s contacts cleaned once a year and the Hewlett Packard is also a pain because it uses three relatively expensive batteries which only last about 2 years.

After HP brought out the HP-28S, the calculator world seemed to go into stasis. Most new models were aimed at the finance market and, as schools and colleges had banned programmable models, I guess there was little incentive to make progress.

In recent years I have looked at the HP-48/49/50 and derivatives, with better displays and progressively larger memory and faster processors, but nothing that really felt like progress. Texas Instruments (TI) have come out with some powerful beasties with all sorts of functions but, again, nothing that really floated my boat. Except…

…Someone managed to get Manic Miner running on the TI-89 and 92+. I was seriously tempted at that point. But it was still very limited grey-scale, and looked more like a toy than a serious tool for science and engineering. My fx-3600p and HP-28S may be old, but they look like they were designed to do a job and to work for a living, not like My-First-Mobile-Phone for 4 year olds.

Yes, But What's The Point Of All This?

So, why am I saying all this? I mean, a chunk of life story is all very nice if you are my mother, and a whinge is good for letting off steam (come on, this is a blog) but what is my point? Well, my calculators aren’t getting any younger or more reliable, so I am now reluctantly in the process of looking around for a new one.

Below, you can see a couple of pages from the 1984 edition of the seminal consumer work The 1984 Argos Catalogue (aka the laminated book of dreams). See the selection available? There are seven programmables and many more scientifics. Now – not a single programmable one. These people sell full SLR cameras, iPods, iPhones, iPads, laptops and a million and one mobile phones, but just 8 scientific calculators.

Argos Catalogue 1984 - Calculators

So I looked a little further afield, and went to the manufacturers’ web sites to have a look at their key models.

Hewlett-Packard  

HP-35S, HP-39GS, HP-40GS, HP-48GII.

HP-50G Calculator

With the top of the range model, the HP-50G (pictured above). All these calculators are based on the ARM-9 powered HP-49 architecture and are manufactured on behalf of HP by Chinese company Kinpo. As you might expect, the quality took a nose-dive when HP stopped performing their own R&D and manufacturing, some time around 2003, with various complaints about a lack of key feedback, software bugs, and general build quality. Even Kinpo's web site seems to be bugged and missing pages.

Although they have improved the key feel in recent model revisions, the HP-50G still spurns the traditional (and excellent) shaped buttons which HP used in their earlier models. The up/down/left/right and function buttons also look rather dated in the age of touch screens. Note also how big it is in an adult male's hand. The UK price is a fairly reasonable £90 (new on Ebay, May 2011 price) or £90:34 excluding P&P on Amazon, but it looks too much like a toy to be taken seriously. Sure it has an SD card socket (not SDHC) and infra-red comms, but in these days of Bluetooth and WiFi those features only succeed in making it look even more outdated. A sad end to a noble brand.

Texas Instruments

TI-83+, TI-84+ (Z80 based)
TI-89 Titanium, TI-92 and Voyage 200 (68000 based)
TI-Nspire series (ARM based): Clickpad, Clickpad+CAS, Touchpad, Touchpad+CAS, CX, CX+CAS

The TI 73/83/84/89 Look very similar to the HP graphing calculators, so it is a fair bet that they are after the same market segment. The TI-89's design is notable in that they seem to have angled the keys closest to the edge, making them look a bit like a mobile phone design from a few years ago.

Texas Instruments
TI-89 Titanium

The TI-92 and Voyage(tm) 200 have an added QWERTY keypad (I can't really call it a keyboard). The effect is that it looks like it has been designed by a committee of 12 year olds who wanted EVERYTHING. NOW. We will hear more from these 12 year olds shortly... Quite honestly, if you can cope with something the size of the Voyage 200, then you should probably be using a netbook.

Texas Instruments TI Voyage 200
"Design - We've heard of it"

And now... (big fanfare)... The TI-Nspire Series. When I heard about the new TI Nspire series of calculators, I got really excited, and that isn't something that happens a lot with me (as you can imagine). ARM processor, full colour high resolution backlit LCD, real time 3D graphing, integrated rechargeable battery, USB, all in a slim case. Brilliant! I thought "This is what the market needs, something to move things into the 21st century, the calculator for the iPhone generation". Then I saw it. Oh mother...

The committee of 12 year olds are now 14 year olds, and they still want EVERYTHING. Except design, style, taste, and usability. The TI Nspire CX is 200x100x27mm. That is over an inch thick and 32 square inches of desk space. I calculate that it is double the volume of my already chunky HP-28S. And besides – look at the thing! Just in case you are under the mistaken impression that it is still pocket calculator sized, here is another view courtesy of TI:

Hang on - didn't TI say this thing was slim? My iPod touch is 8mm thick, this Nspire CX is 27mm. What are you talking about TI? It is very telling that TI is aiming these at the "educational" market. In other words, school children.Great, but what about us people who have left school and are now working for a living? Add to this the reluctance, actually no not reluctance - fear - TI seem to have of independent developers (call them hackers, makers, developers or for that matter simply enthusiastic owners) then I think we can remove all TI products from our virtual list of potential calculators.

Anyone considering playing around with TI calculators should read this: Texas Instruments Learns Nothing, Goes After Hobbyists Again

and this: TI vs. Calculator Hobbyists – AGAIN

TI seem to be in the increasingly large collection of companies which are under the impression that they can control the Internet. This tells me that lawyers are running the company, not engineers.

Casio 

FX-CG10 (FX-CG20) (new),
FX-9860GII (new), FX-9860GII SD (new),

Casio fx-9860GII SD

FX-9750GII (new), FX-9750G+,
FX-7400G+
CFX-9850GC+
FX-9860G, FX-9860G SD

That's a lot of calculators, and a lot of "number and letter soup". Too much, to be honest. Especially if you add the SD card options. I'm generally not keen on the curvy pseudo-phone look of the case, but at least the FX-9860GII adds -gasp- a backlight! Still, it is only a clunky monochrome screen with the usual set of applications we see elsewhere. I'm pushed to distinguish it from the HP-50G and TI calculators. It probably looks a bit more professional than the TI machines, but only marginally.

Fortunately, Casio appear to be changing direction. Presumably being forced by the appearance of TI's colour screen devices. The PRIZM FX-CG10. Urgh, not only a mis-spelled word, but in capitals too. For added confusion, it will be known as the FX-CG20 in the UK. I guess their marketing guys had to invent more work for themselves.

Casio PRIZM FX-CG10/CG20

Anyway, the FX-CG10/20 at least looks like it belongs in this century. They still seem to feel compelled to make the keys look like something from a mobile phone, and the colour screen is obviously not a touch screen, but it is a good start. No processor type is stated (my guess would be one of the ARM family) and the screen is lower resolution than TI's Nspire uses, but it looks a whole lot more professional. Almost HP-like in fact. Almost.

Will I be buying one though? Hell no. The UK price isn't too bad at £105, but it still doesn't do what I want it to do.

A quarter of a century on from the launch of my HP28S, I think we deserve more. There is no shortage of mathematical horsepower from ARM chips, nor is there a problem with memory prices or displays. Touch screens should be standard, removing the need for function and cursor keys (in this instance, a resistive screen would be better than a capacitive one, allowing the user to enter symbols directly with a stylus) but numbers and core functions should be retained as proper hardware keys with shaped buttons.

Software should be much more along the lines of the commercial heavyweights like Matlab or Mathematica. Wolfram Alpha is an obvious example of what the software should aim to be. I am not suggesting it be an iPod/Pad/Phone though, a calculator still needs to retain the immediate usability of conventional designs, whereby you can just flick a switch, and it is on and ready for use. Of course the real way of making it a killer product would be to open the OS and publish the hooks into the software, and to invite users to add to the available software. Pretty much the opposite to TI's attitude.

Conclusion (Yeah about time too!)

Hewlett-Packard
HP-35S

So, they are all useless? Well, useless is probably putting it a bit strongly, but I am disappointed that calculators haven't evolved more. The processor power available from ARM chips is hardly being used at all.

I am tempted to buy a Hewlett Packard HP-35S. It is made by Kinpo (urgh) and the OS is seriously buggy - to the point that the OS can crash, or erroneous results can be generated. But it looks a much more professional than anything else on the market. Come on Kinpo - sort it out! The HP-35S was brought out to commemorate the 35th anniversary of the original HP-35, but is the logical successor to the recent HP-33S. A calculator whose keys were angled in a V-shape, to look like - you guessed it - a mobile phone. It seems that someone at HP or Kinpo actually realised that professionals don't want their tools to look like a kids toy!

Is it too much to hope that someone might perhaps produce a successor to the superb HP-41 series? This calculator still has a huge amount of following, to the point that a number of emulators are available. Most notably, an emulator for the iPod/iPhone/iPad from Alsoft. Not only does it fully emulate an HP-41CX (including printer) but they have added GNUplot functionality too. Best of all, it is priced at just £15. HP are asking £30 for their HP-35S emulator.

Alsoft's i41CX+

Is this the future for calculators? I hope not. I would miss being able to turn on a physical calculator in a fraction of a second, and to receive direct feedback from the keys. I hope it will alert HP (and TI and Casio) to the untapped potential out there.

I would love to hear from anyone out there who has an opinion on this. I guess I am merely on the fringes of calculator geek-dom, I know there are some real collectors out there who go to extreme measures to get just the right calculator with an early serial number, but to me they are primarily an important tool and it frustrates me that nobody seems to make the right one for me.