I am writing an application for POS systems and need a bit of understanding of them. I know that all POS systems have some OS platform on which they work either a normal OS like windows XP/7 or a small footprint one like Windows CE or so. As much as I know, there can be different peripheral hardware units like printer or cash drawer and they can be of different kinds (different manufacturers and models). So I considered that usually these peripherals say printer have its driver installed on windows which is being used by the POS software to trigger printing.
But as I have searched and have seen several POS systems (deployed and not from close), i may very well see there are POS systems which are fully integrated and the print is triggered by payment say, through a swipe of card on card swipe machine. The hardware seems to be of same company (for peripherals and POS) and so I doubt the mechanism does not involves the installation of drivers on OS platform. Rather in such cases, the POS software itself contains the drivers of peripherals and trigger them. There is no call to default printer on the OS but a direct call to the thermal printer attached. This may be happening using some ADK/SDK to control peripheral or APIs exposed by peripheral manufacturer or simply drivers wrapped up in POS software itself.
My question is, is my understanding here correct or does everything goes via OS drivers only? If I am thinking write, then can somebody tell what kind of mechanism such POS systems use (i mean sdk or API or driver wrapped in POS software or what)?
Yes, such POS systems exists. E.g. our own POS software talks directly to peripherals using the native protocols of the respective devices. Of course you must then understand the protocols and, in the case of printers, their emulations, e.g. ESC/POS, ESC/Label, Fingerprint etc.