Multi-purpose vs purpose-built computing

Multi-purpose shelf is not as optimised as wardrobe for storing clothes. Photo by omegafotos

We can’t help but see purpose-built computing slowly being replaced by multi-purpose computer hardware and Operating System, namely the Personal Computer (PC) architecture. We will see some examples described in more details below, but before that, let’s take a look of why this can take place. On the face of it, it seems like multi-purpose things will always be less optimised compared to purpose-built things. After all, generic storage shelf will never be as optimised as wardrobe for storing clothes, bookshelf for storing books, or refrigerator for storing food. However, few important trends converged to make multi-purpose computing a better platform nowadays than purpose-built computing:

  • standardisation. When PC was born as hobbyists’ tool, all PC makers had their own specifications. Everybody had different idea of how to make a PC, and minimal interoperability was available between different makers.  Then, when IBM created IBM PC as pet project of some its engineers, it decided that they will make the specification open for any interested parties to see. This, alongside the weight of the IBM name in computing, caused mushrooming of IBM PC-compatible makers and consumers choosing this as favourite PC platform, slowly edging out other PC architecture that had come out earlier
  • B-2 Spirit costs $2b+ per aircraft because the R&D cost can only be spread over 21 units. Photo by Staff Sgt. Bennie J. Davis III

    economies of scale. In any technology products, one of the largest cost component is the amortisation of Research & Development (R&D) costs. Produce and sell enough products and the unit cost of the R&D amortisation goes down, resulting in end price that is more friendly to the customers. B-2 Spirit is a case in point for technology economies of scale. Wanna know why each B-2 Spirit aircraft costs over US$ 2 billion? Well, because the United States Air Force only made 21 of them. If they made 132 of them as initially planned, each aircraft would have cost less than half of that. It is worth noting anyhow, that even though economies of scale has depressed the price of PC platform, it’s not always cheaper than the purpose-built ones. Its price has simply gone down low enough for it to be considered as alternative platform

  • product innovation. In the bloody battle to win bigger share of the ever growing PC market, incredible rate of innovation took place. The results are, quite frankly, new PCs which are simply too powerful for the majority of their users. And that’s not always a bad thing. Computation that was deemed impossible to perform on a PC is now well within the capability of PCs, resulting in creative new ways to use PC beyond just for personal use

Now let’s take a look at some examples on how multi-purpose computing is replacing purpose-built computing


Photo by Jenny Rollo

One of the driver for transition of Point-Of-Sales (POS) systems from purpose-built to PC platform is ease of integration. In any retail establishment, POS system is far from being the only computerisation needed. At the very least, it also needs integrated accounting software which handles purchasing, inventory, and financial accounting. The POS system, which handles the sales activities of the business, will then have to be integrated to this integrated accounting software. You can call the POS system as front office solution and the integrated accounting software as back office solution. Basing the POS system on PC platform drastically simplifies integration.

The system unit in PC-based POS system will run the POS software sitting on top of a small database server. The POS software provides the following functionalities:

  • product list. This should ideally be obtained from the integrated accounting software
  • price list & discount scheme
  • Sales Order. This data will later be pushed back to integrated accounting software
  • option to record the customer identification number. In retail environment, customers will rarely volunteer to give their personal details like name, gender, birth date (for age calculation), address, contact number, etc. These information, however, is vital for the retailer to be able to profile its customers and analyse their buying pattern. So, what retailers usually do to get this is to give out membership card with some ancillary benefits like future discounts.
  • understand the data format contained within the magnetic strip of credit cards as well as basic verification of credit card number
  • ease of customisation to be able to control the specific additional hardware peripherals which form parts of the POS system like receipt printer, cash drawer, and some secondary display

As we can see above, the integration between POS system and integrated accounting software is 2-way. Having based the POS system on PC platform, numerous options are available for these integrations, ranging from simplistic like table dump, to moderately advanced like regular ETL (Extract, Transform, and Load), to cutting edge like Service-Oriented Architecture (SOA).

Before we conclude the discussion on POS system, let’s take a look at some specific additional hardware peripherals needed in the POS system and how they work in PC platform:

  • Receipt printer is basically just like any other PC printer but can only print on narrower receipt paper roll. It is connected to the system unit just like any other PC printer too. However, it usually has additional connector (usually RJ11) to the cash drawer. To open the cash drawer, the POS software has to send certain control sequence to the receipt printer
  • Cash drawer. This can be connected to the system unit (usually via RS-232-compatible serial port) or to the receipt printer (usually RJ11). When connected to the system unit, the cash drawer can be opened by simply sending certain character(s) (or sometimes any characters) to the serial port it is connected to
  • Secondary display. The older models, usually distinguishable by being monochromatic LCD display, need some coding to be able to control their display. The newer ones are simply smaller LCD monitors which make use of Microsoft Windows multiple display feature
  • Smart card reader for reading credit card information. This can either be obtained as integrated keyboard & card reader unit or as separate keyboard wedge card reader. Emulates keyboard and just send the data it reads as key strokes.
  • Bar code reader. For faster check out, may consider multi-beam laser scanner so that the bar code on the merchandise can be read at any angle. Usually sold as keyboard wedge, so its input are considered normal key strokes from keyboard

Private Automatic Branch Exchange

The advent of digital telephone lines few decades back paved the way for Information & Communication Technologies (ICT) convergence. One of the results is Internet Protocol Private Automatic Branch Exchange (IP PABX). This piece of equipment is computationally heavy. Hence, it was just a matter of time before somebody ported the capability to the most widely available multi-purpose computing platform: the PC platform. To read more about IP PABX, click here. The hardware used for IP PABX is pretty much standard-issued PC hardware plus interface cards for connection to Public Switched Telephone Network (PSTN) or analog telephone extensions.


Photo by Daniel Battiston

Since facsimile technology revolves around sending digitised image of paper documents, it is a good candidate for shift toward multi-purpose computing hardware. It especially makes more sense in businesses with multiple facsimile telephone lines. Changing the facsimile hardware to PC platform bypasses the final conversion from digital image to physical document, resulting in savings from the use of less paper, especially if the document is addressed to multiple persons within the company. On top of that, faxed documents can be easily forwarded to intended persons via existing e-mail infrastructure. All it needs to convert a PC-based hardware into fax server is a fax server software and modem(s).

Automatic Teller Machine

Photo by Vaughan Willis

The reason for the switch of Automatic Teller Machine (ATM) to PC platform is because the ATM has to be able to do quite a lot of things that the PC platform can already do very well, namely:

  • communicate securely (i.e. using encryption) to the bank’s remote data centre which holds the account information and more
  • provides User Interface (UI) so that the bank customers can issue banking orders in user-friendly manner
  • coordinates input (via the ATM’s keypad and buttons) and output (through the receipt printer)
  • probably even play advertisement movies about the bank when the machine is sitting idle. This is really just a screen saver and indeed one of the main functions of this is to prevent burn-in on the ATM display caused by displaying same image for extended period of time
  • detect physical security breach (cover being opened without being unlocked first, etc)
  • auto-restart in event of extended power failure (longer than the battery span of the Uninterruptable Power Supply installed within the machine)
  • well-documented interface to additional hardware peripherals such as smart card reader, customised keypad, and cash dispensing mechanism

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