Device Drivers II

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The first experience was in DOS. MSDOS ICON Here the difference between a TSR (terminate-and-stay-resident) and a device driver can be very small. Of course the device driver begins with a very special header, while a TSR is actually an executable that keeps some of its code active while the system remains on.

Now it can be in the MS Windows WIN ICON device driver model. There have been various flavours, commencing with the very powerful VXD and SYS file of Window 3.1 and 3.11, through Windows 95/98 SE, and Windows NT, onto the current Microsoft Windows 2000, XP (WDM), Operating Systems, and seemingly ever onwards.

Nearly always in my case the emphasis has been computer to computer Like lighting between machinescommunications. In the early programming days that was PEP (aka Personal Emulation Package). This special "driver" took over just about all DOS functions and allowed toggle between the "captured" DOS OS and the PEP Uniscope character emulation screen.

Originally communication was via a purpose built AT Bus card that performed synchronous data communications up to the fastest speed at that time of 9,600 baud. A PEP card, so the real "device driver" part of the code provided the bridge between the on board Zilog 8530 sync. chip and the "screen". More can be read about the Company I ran to sell this PEP product in my Working Experience, Page 1, and Page 2.

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