In every OSDI pack the file DIPx.C is provided, where x is the DP4 operating system code (w=Windows, 2 = MS-DOS, 3 = Unix/Linux, 5 = FlexOS, 7 = OS/2). DIPx.C provides the code for the DP4 Terminal Manager interface. You do not need to understand or modify this code. For some operating systems other "private" source files may be supplied. In all cases these files will be supplied pre-compiled (see the section on compiling and linking the OSDI for detail on compilers).
For each operating system DP4 also supplies a file containing user-modifiable functions. This file is named according to the operating system as follows:
These modules contain some example code which differs between operating systems. However, except for Windows, they all contain the following functions, which you may modify in order to interface between a DP4 application and your Device Group:
prg_start()
prg_stop()
prn_select()
prn_parameters()
prn_print()
prn_status()
prn_deselect()
inp_start()
inp_restart()
inp_stop()
inp_task()The Windows OSDI contains different functions and is dealt with here.
In the following sections, these user-modifiable functions are described. Example modifications designed to access the DP4 Till are presented for some cases. The examples match the example definitions from the section about DFSETUP, and also the examples in the application programming section.
The DP4 Till code shown is incomplete - no operating-system dependent code is shown. Such functions would make specific calls on the DP4 Till hardware. You could implement them in a simple fashion by designing a Till simulator. In that case all the Till hardware functions (status requests, output and so on) would result in a descriptive output on your terminal.