Some Differences Between MS-DOS, Windows, Unix and SCIOS

To the sophisticated MS-DOS users, there are certain actions taken in SCIOS which seem peculiar. These are done for a reason. During the execution of most MS-DOS programs simply naming a file causes it to be created in the event it does not exist. This can cause terrible problems.

In SCIOS a user must explicitly define a file before it is available for use as an output file. This means that for a user to make a mistake in specifying an output file name, he must makes the same mistake twice. Once when he defines it and once when he uses. In SCIOS a file may be defined through the use of the define command at the operating system prompt >>? by typing DEFINE [filename]. Within a program in any command line where a data file name is asked for, the user may precede the data file name with a + with no intervening spaces. The system interprets this as a statement that the user wants to define it in the event it is undefined and to clear the write protect flags in the event it is a read only file. The second basic difference is that in MS DOS a user may create batch files (normally named with the extension .BAT). To execute this batch file the user types the name of the batch file (without the .BAT extension). In SCIOS the same thing is true except that there is a command AC (for assign console) that is used to tell the system that the name following it is to be interpreted as a batch file. In both MS DOS and SCIOS positional parameters may be provided on the command line to offer information for substitution into the batch file.

The MS-DOS and Windows NT Version of SCIOS

For years, the Synergistic Consultants Incorporated Operating System, SCIOS, has been produced to execute on a variety of different computers. In every case, those routines deep at the heart of the operating system which are called the file access routines have been written by SCI and embody novel and proprietary disk access techniques. These are the routines called by all higher procedures of the operating environment to carry out all file open, read, write, position, and close activities. These routines as they have been written are quite efficient, but these impose on the user an additional burden of responsibility with regard to data base generation and maintenance.

Some time ago SCI undertook the task of rewriting the file access routines to make use of the DOS interrupt 21H. As a result of replacing these routines, it is possible for the user to carry out functions identical to that which was possible before, yet now ordinary DOS files are created and maintained. Although the two newer versions of SCIOS execut a bit more slowly than the older "Classis SCIOS", the advantages of direct compatibility with other software makes the use of this new version attractive.

No longer must a user find a non DOS portion of hard disk (selected through the use of the utility FDISK) as the preparation of MS DOS is sufficient to bring all of the capabilities of SCIOS to the average user. Because the efficient yet bulky routines of SCIOS have been replaced with MS DOS calls, the load modules of SCIOS are significantly shorter.

The directory searches are provided by an ordinary MS DOS DIR command. The executive commands LABEL (to look at the data base label) and PASSWORD are no longer needed as we may no longer PASSWORD protect a data base. The executive command SCIOSGEN is no longer needed as the new version will use whatever directories and subdirectories have been provided through normal MS DOS activities. With all of the above, all of the features of SCIOS have been maintained i.e. to conveniently create display files, compile chaprola procedures, produce and compile replica report procedures as well as to execute utilities such as archive, ASCII text to post script translation, communication with a post script laser printer as well as communicating as an intelligent terminal through a modem to another device.

The load modules for local use on the server computer are called XSCIOS.EXE and SCIOS32.EXE, for the MS DOS and Windows NT versions, respectively. These each contain all of the programs normally supplied in the well known operating environment. Both are ordinary .EXE files in the MS DOS sense , except that the Windows version must be executed in the Windows enviornment. The Internet version is called CGIentry.exe and is intended for use in a networked enviornment, not for local use.

The installation of this system is simple: once the user has changed directory to his desired location, he simple inserts the installation medium (a CD-ROM or floppy disk) and types the command: COPY A:*.*. This will copy all of the files contained on the installation disk into the default directory. Usually there will be some additional files, eg DISPLAY, CHAPROLA and REPLICA which are the assign console files for carrying important functions are included on this installation disk. Installation is now complete.

To enter the SCIOS environment for local use, it is only necessary to type either XSCIOS or SCIOS32. Immediately, the SCIOS prompt will appear. The knowledgeable user will see that the system no longer asks for a data base location and password, as these are no longer necessary. To return to the MS DOS prompt the user need only type SYSTEM. Therefore, the user may bounce back and forth between the SCIOS operating environment and the MS DOS operating environment. The files that are created are MS DOS files and obey all of the rules of MS DOS with regard to file structure. The knowledgeable user will notice immediately that most files are larger than they were in the SCIOS environment. One reason for this is that with ragged sequential files (text files) a carriage return and line feed are used in lieu of the carriage return which the classic SCIOS has used. (A knowledgeable user may be interested in learning that UNIX uses a line feed instead of the SCIOS carriage return). A control Z may be used to mark the end of file in asequential files, but this is not necessary. Nonsequential or random access files do not use this convention. You will notice that while editing sequential files every time a file is rewritten the file is shortened to the maximum extent.

In XSCIOS, the handling of the two serial ports is done with the same level of sophistication that it was in the Classic version. Full interrupt control is used by overpainting the interrupt vectors on entry for these two devices. These are restored on exit. While in the SCIOS environment you are assured that no character is lost even though at that instant you may be compiling a program or doing some other kind of task that has diverted, apparently, the computers attention from the serial ports.

Files may be backed up through the MS DOS BACKUP command or if the user chooses, the much more efficient and flexible SCIOS ARCHIVE program may be employed. The XFERIN and XFEROUT commands are still active, but it would appear that these have no function. They have been left there for a reason.

When part of the file access routines are replaced with yet another set of routines to talk, not to MS DOS but to a networking controller, a full networked version of SCIOS will be achieved. The networking version will be available to SCI clients expressing an appropriate need (this is the CGIentry version.)