An operating system is started first. Then, using a program running in that environment, a further operating system is started. That program is able to start a kernel of the goal OS stored in a file in a DOS directory. The procedures for starting ETH Oberon and Linux in this way are so similar that everything boils down to this simple statement: the DOS-program noboot.exe is to ETH Oberon what loadlin is to Linux. This should become clear when looking at the example CONFIG.SYS and AUTOEXEC.BAT files below.
The correspondance is as follows (the names are indicative, not imperative):
It is not even necessary to have a (minimal) DOS partition on hard disk. A DOS boot diskette is enough.
Advantage: Adding a partition does modify the partition table in the MBR, but apart from that the MBR is not altered. Hence, the danger of malignous side effects due the addition of an OS, like ETH Oberon, to a system is minimized. The partition can be placed anywhere.
The following was tested with MS-DOS only but should also be applicable to IBM DOS, Caldera DOS and IBM DOS 2000. noboot is the DOS program which loads the Oberon kernel stored in a DOS directory in a file usually named "native.bin". The load process is directed by configuration specifications contained in another file (usually "native.par") stored in the same directory. noboot integrates itself seamless in an existing DOS or Windows 95/98 environment and can be used with most of the boot managers.
noboot requires a bare-bone DOS system and no more. If Oberon fails to start, e.g. hangs in the middle of the boot process, analyze the CONFIG.SYS and AUTOEXEC.BAT files and REM the lines related to memory management. In particular, those mentioning HIGH, or those involving the use of EMS or XMS. Alternatively, force Oberon to enter debug mode using the option -d mentioned below.
Start Oberon at the DOS prompt by executing the command:
If the running system is Windows 95/98, MS-DOS 7.0 is be started by restarting Windows in DOS mode or by pressing Shift-F5 when Windows starts. noboot is started in DOS-mode from the user interface. A special icon native.ico is provided for that purpose.
It is not possible to switch directly from Windows NT to Oberon. A DOS boot diskette or an additional, minimal DOS partition must be started in that case, via a boot manager for example.
These example texts control the access to three co-resident Oberon systems: MS-DOS, Oberon, Linux.
1 - Example NATIVE\NATIVE.PAR file
2 - Example CONFIG.SYS
3 - Example AUTOEXEC.BAT
4 - Example NATIVE\NATIVE.BAT