The story as to how people developed different number systems and aids to calculation – cumulating in today’s calculators and computers – is a fascinating tale. The following topics are abstracted from a bonus chapter entitled The History of Calculators, Computers, and Other Stuff” provided on the CD-ROM accompanying How Computers Do Math.

The First Aids to Calculation The History of Number Systems The First Mechanical Calculators The Golden Age of Mechanical Calculators Some Cool Mechanical Calculators The First Electromechanical Calculators The First Electronic Calculators

Logic Diagrams and Machines The First Mechanical Computers The First Electromechanical Computers The First Electronic Computers The First Microprocessors The First Personal Computers The First and Worst Computer Bugs

These days, we tend to take things like computer keyboards and high-resolution graphics displays that provide bright, vibrant images for granted. But where did these devices originate and how did they evolve into their present forms? These questions and more are answered in the following topics.

The Origin of the Computer Keyboard Paper Tape and Punched Cards Switch Panels and Light Displays     (Coming Soon)

The Origin of the Computer Console ASCII, EBCDIC, and Other Codes Memory and Storage Technologies     (Coming Soon)

The human brain and visual cortex are capable of processing huge amounts of visual data. In fact, studies have shown that we receive approximately 80% of our external information in visual form. Generally speaking, however, most of us tend to take our visual capabilities for granted, especially when it comes to color vision. More...

One thing about history is that there's an awful lot of it about. The history pages featured in the previous topic cover a lot of ground, but there's always so much more to discover. Thus, as we've run across interesting nuggets of trivia over the last few years, we've squirrled them away, and we now present them to you as a suite of timeline tables. More...

This paper describes the concept of a mixed-technology computer that we are proposing to build out of relays, vacuum tubes, transistors, and simple integrated circuits (silicon chips), along with more esoteric technologies such as pneumatics and hydraulics (and don't ask us about the hamsters). More...

Traditional techniques for increasing computational performance and throughput are starting to run out of steam. When a conventional processor cannot meet the needs of a target application, it becomes necessary to evaluate alternative solutions, such as multiple processors, arrays of processing elements, and "great big piles of gates." More...

The virtual microprocessor featured in the DIY Calculator contains a single accumulator, an index register, and a stack pointer. Over the years, computer architects and design engineers have experimented with a variety of different architectures, such as multiple accumulators, additional general-purpose registers, and so forth.

The discussions in this topic introduce some interesting developments and considerations, such as von Neumann versus Harvard architectures, RISC versus CISC, multiplexed data and address busses, multiple accumulators versus general-purpose registers, and ... the list goes on. Coming Soon...

As was noted in the previous topic, the virtual microprocessor featured in the DIY Calculator contains a single accumulator, an index register, and a stack pointer. In this topic we introduce the architectures associated with some of the early microprocessors, such as the Intel 4004, 4040, 8008, and 8080; the Zilog Z80; the Motorola 6800 and 6809; and the MOS Technologies 6502. Coming Soon...

We all remember being taught the concept of rounding in our younger years at school. Common problems involved monetary values, such as rounding some amount like $5.19 to the nearest dollar (which would be $5 in the case of this example). However, although this may seem simple at a first glance, there's a lot more to rounding than might at first meet the eye. More...

The calculator program we develop in our book, How Computers Do Math, is a simple four-function (add, subtract, multiply and divide) tool that works only with 16-bit integers. In reality, of course, this is very limiting, because it means that we can’t represent real numbers like 3.142. Thus, in this topic we introduce the concepts of fixed-point and floating-point representations and calculations. Coming Soon...

The previous topic introduced the concepts of fixed-point and floating-point representations in general terms. In this topic we consider the special considerations associated with binary floating-point representations and define our own 1-7-16 format (1-bit sign, 7-bit exponent, and 16-bit mantissa). These discussions will form the basis for some binary floating-point subroutines that we will develop in the not-so-distant future (see also the Subroutines page on this website). Coming Soon...

Many folks belittle the binary coded decimal (BCD) format, in which each digit in a decimal number is represented by four binary bits. However, there are a lot of interesting aspects to this format of which one should at least be aware (not least the trials and tribulations associated with wrapping one's brain around the concept of tens complement arithmetic). More…

The previous topic introduced the core concepts of Binary Coded Decimal (BCD). Now we are in a position to combine our knowledge of BDC and floating-point arithmetic (as discussed in an earlier topic) so as to consider a BCD floating-point implementation. These discussions will form the basis for some binary floating-point subroutines that we will develop in the not-so-distant future (see also the Subroutines page on this website). Coming Soon...

The virtual version of the DIY Calculator used in How Computers Do Math provides a fantastic tool for learning about computers and calculators. However, there is something satisfying about having a real machine to play with, so we’ve been pondering the idea of creating a physical version of the DIY Calculator. In fact, some students at Newcastle University in the UK have already created VHDL models for the DIY Calculator and created an FPGA-based implementation. More…

Hot News! Two electronic engineers in Austria (Johannes Hausensteiner and Helmut Zulus) have started a project to implement a physical version of the DIY Calculator using a Field-Programmable Gate Array (FPGA). We can't wait! In the meantime, they've started a Wiki documenting the project.

In addition to all of the cool material you'll discover as you meander your way around our website, there are a lot of other really cool sites to visit, peruse, and ponder. A few of these sites are as follows (we'll be adding more as time goes by):

Are you interested in old transistors? Well, Jack Ward has created an amazing Transistor Museum website with great articles, a must-see photo gallery, oral histories, and much, much more!

Harry Porter, a lecturer at Portland State University, has created an incredibly cool Relay Computer. His website includes photos and videos of this little scamp (it's great to hear the relays clattering away). We want one!

John Wolff is an Australian engineer with a deep interest in mechanical and electronic calculators. If you visit John's Website, you'll see that he has torn down, cleaned, and rebuilt a number of machines, taking lots of superb photos of their innards, which he describes in considerable detail.

Claiming to have been "Wasting time online since 1993," Josh Madison has created an incrediby useful program called Convert that you can use to convert the most popular units of distance, temperature, volume, time, speed, mass, power, and so on. You can download a free copy from the Convert page on Josh's website.

Proponent of structured (verbal) numbers, calculator enthusiast James Redin has some cool virtual calculators and a wealth of historical information at his Xnumber website.

Calculator collector Nigel Tout has an amazing collection of calculators through the ages. You can find details and see photos at his Vintage Calculators website.