Operating Modes and the Command Line

Operating modes can be specified on the command line when starting the simulator.

Normal Expanded Wide

This is the default operating mode, which is the default operation of the Motorola EVB. It is typically necessary to do some initialization when using this mode, usually by loading DBUG12.S19 and running its startup code.

Requested Mode

So named because it was requested. This is identical to the default mode except the internal RAM memory is not initialized by power on reset (the File...Reset menu item). Apparently some people want to put programs in the internal RAM memory instead of external RAM or ROM. To run in the requested mode, add "-r" to the end of the command line but before any .S19 files.

Student Mode

This is Normal Expanded Wide with several important changes: the COP system is disabled, the reset vector at $FFFE is initialized to $4000, and the clock stretch for the "external" memory is set at 1 E-Clock. The external memory access is enabled (actually it is in the default mode, but it might not be in the future). The internal RAM memory is not initialized by power on reset (the File...Reset menu item) in student mode. To run in student mode, add "-s" to the end of the command line but before any .S19 files.

64K RAM Mode

This is Normal Expanded Wide with 64K of external RAM attached. It doesn't represent the Motorola EVB, but is probably the easiest mode to use. To enable this mode, add "-m" to the end of the command line but before any .S19 files.

Normal Single Chip Mode

The EEPROM is relocated to $F000-$FFFF and the external memory is no longer accessible. This is equivalent to changing the MODA and MODB header jumpers on the Motorola EVB to place it in Normal Single Chip mode. To run in normal single chip mode, add "-c" to the end of the command line but before any .S19 files. Note that all modes are mutually exclusive.

Expanded Narrow Mode

In this mode, the chip is configured for an 8 bit data bus. This effects instruction timing. To run in Expanded Narrow mode, add "-n" to the end of the command line but before any .S19 files.

68HC912B32 Mode

In this mode the 68HC912B32 is simulated running in single chip mode. The PWM is not available and all other features are available to the extent they are in the other modes (ATD, SCI are available, SPI is not). The Flash ROM from locations $8000-$FFFF is not loadable programmatically, but can be loaded from S19 files or through the user interface. To run in 68HC912B32 mode, add "-b" to the end of the command line but before any .S19 files.



After any mode commands on the command line, .S19 format files can be listed. If the file name extension is missing, ".S19" will be appended to the file name automatically. These files will be loaded automatically at startup. If any files are listed, then a power-up reset is performed.

For instance,

jre -cp simhc12.jar SimHC12 -s problem1.s19 dbug12.s19

will start the simulator in Student Mode, load the files problem1.s19 and dbug12.s19, then perform a power-up reset.

Note that the documentation directory (folder) is expected to be in the folder that the simulator is run in. An addition option "-ppath" can be used to specify the path to the directory containing the documentation files. The path can either be absolute (starting at the root directory) or relative to the current directory.