On this example one of the clips has been broken, sadly I can’t remember if this was caused by an enthusiastic but inept younger me. The upper and lower halves of the case are held together with moulded clips, meaning that with care they can be pried apart to reveal the circuitry. At rest the calculator draws 35 mA from them, so an owner without deep pockets would have had to ensure to turn it off immediately after calculations. The label recommends Duracell AAAs, which in the mid 1970s were not cheap. One of the clips had been corroded by a leaking cell and had snapped when I got the calculator, necessitating a piece of copper foil between cell and clip for operation. Opening it reveals the underside of the keyboard PCB with a label showing battery orientation and the springy battery clips for a set of 4 AAA cells. On the back there is only the clip-on cover for the battery compartment, which lies under the keyboard. The Sinclair Scientific circuit board, component side. Good industrial design does not age, and while the Sinclair’s design makes it visibly a product of the early 1970s space-age aesthetic it is nevertheless an attractive item in its own right. At 50 x 111 x 16 mm it is a true pocket calculator, with an elegance many of its contemporaries failed to achieve and which is certainly not matched by most recent calculators. The LED display sits behind a purple-tinted window, and the blue-and-black keyboard occupies the lower two-thirds of the front panel. It shares the same external design as the earlier Sinclair Cambridge, a more humble arithmetic calculator, but where the Cambridge’s plastic is black, on the Scientific it is white. On the inside of the case is a crib sheet for its RPN syntax and scientific functions, an invaluable aid when it comes to performing any calculations. The Sinclair is protected by a rigid black plastic case, meaning that it has survived the decades well. What follows will not be the only teardown of a Sinclair Scientific on the web, after all nobody could match ’s examination of the internals of its chip, but it should provide an insight into the calculator’s construction, and plenty of satisfying pictures for lovers of 1970s consumer electronics. Looking at it though as an adult, it becomes obvious that this is an interesting machine in its own right, and one that deserves a closer examination. The Sinclair’s clean design still looks good four decades later.
#FRIDEN CALCULATOR 1956 FULL#
But then as life moved around me it went into that storage box, and until the RPN article that’s where it stayed. Finding it was a significant task, to locate something about the size of a candy bar in the storage box it had inhabited for two decades, among a slightly chaotic brace of shelves full of similar boxes. Even in the early 1990s (and even if you didn’t use it), having a retro calculator on your bench gave you a bit of street cred. I bought the calculator in a 1980s rummage sale, bodged its broken battery clip to bring it to life, and had it on my bench for a few years. This was an important model in the genesis of the scientific calculator, not for being either a trailblazer or even for being especially good, but for the interesting manner of its operation and that it was one of the first scientific calculators at an affordable price. When writing a recent piece about Reverse Polish Notation, or RPN, as a hook for my writing I retrieved my Sinclair Scientific calculator from storage.