The user interface

The GUI of EduMIPS64 is inspired to WinMIPS64 user interface. In fact, the main window is identical, except for some menus.

The EduMIPS64 main window is composed by a menu bar and six frames, showing different aspects of the simulation. There’s also a status bar, that has the double purpose to show the content of memory cells and registers when you click them and to notify the user that the simulator is running when the simulation has been started but verbose mode is not selected.

The status bar also shows the CPU status. It can show one of the following four states:

  • READY The CPU hasn’t executed any instructions (no program is loaded).

  • RUNNING The CPU is executing a series of instructions.

  • STOPPING The CPU has found a termination instruction, and is executing the instructions that are already in the pipeline before terminating the execution.

  • HALTED The CPU is stopped: a program just finished running.

Note that the CPU status is different from the simulator status. The simulator may execute a number of CPU cycles and then stop executing, allowing the user to inspect memory and registers: in this state, between CPU cycles, the CPU stays in RUNNING or STOPPING state. Once the CPU reaches the HALTED state, the user cannot run any CPU cycle without loading a program again (the same program, or a different one).

There are more details in the following sections.

The menu bar

The menu bar contains six menus:


The File menu contains menu items about opening files, resetting or shutting down the simulator, writing trace files.

  • Open… Opens a dialog that allows the user to choose a source file to open.

  • Open recent Shows the list of the recent files opened by the simulator, from which the user can choose the file to open

  • Reset Resets the simulator, keeping open the file that was loaded but resetting the execution.

  • Write Dinero Tracefile… Writes the memory access data to a file, in xdin format.

  • Exit Closes the simulator.

The Write Dinero Tracefile… menu item is only available when a whole source file has been executed and the end has been already reached.


The Execute menu contains menu items regarding the execution flow of the simulation.

  • Single Cycle Executes a single simulation step

  • Run Starts the execution, stopping when the simulator reaches a SYSCALL 0 (or equivalent) or a BREAK instruction, or when the user clicks the Stop menu item (or presses F9).

  • Multi Cycle Executes some simulation steps. The number of steps executed can be configured through the Setting dialog.

  • Stop Stops the execution when the simulator is in “Run” or “Multi cycle” mode, as described previously.

This menu is only available when a source file is loaded and the end of the simulation is not reached. The Stop menu item is available only in “Run” or “Multi Cycle” mode.

Note that the simulator slows down when updating the UI. If you want to execute long (thousands of cycles) programs quickly, disable the “Sync graphics with CPU in multi-step execution” option.


The Configure menu provides facilities for customizing EduMIPS64 appearance and behavior.

  • Settings… Opens the Settings dialog, described in the next sections of this chapter;

  • Change Language Allows the user to change the language used by the user interface. Currently only English and Italian are supported. This change affects every aspect of the GUI, from the title of the frames to the online manual and warning/error messages.

The Settings… menu item is not available when the simulator is in “Run” or “Multi Cycle” mode, because of potential race conditions.


This menu contains only an item, used to invoke the Dinero Frontend dialog.

  • Dinero Frontend… Opens the Dinero Frontend dialog.

This menu is not available until you have not executed a program and the execution has reached its end.


This menu contains items related to operations with frames.

  • Tile Sorts the visible windows so that no more that three frames are put in a row. It tries to maximize the space occupied by every frame.

The other menu items simply toggle the status of each frame, making them visible or minimizing them.


This menu contains help-related menu items.

  • Manual… Shows the Help dialog.

  • About us… Shows a cute dialog that contains the names of the project contributors, along with their roles.


The GUI is composed by seven frames, six of which are visible by default, and one (the I/O frame) is hidden.


The Cycles frame shows the evolution of the execution flow during time, showing for each time slot which instructions are in the pipeline, and in which stage of the pipeline they are located.


The Registers frame shows the content of each register. By left-clicking on them you can see in the status bar their decimal (signed) value, while double-clicking on them will pop up a dialog that allows the user to change the value of the register.


The Statistics frame shows some statistics about the program execution.

Note that during the last execution cycle the cycles counter is not incremented, because the last execution cycle is not a full CPU cycle but rather a pseudo-cycle whose only duties are to remove the last instruction from the pipeline and increment the counter of executed instructions.


The Pipeline frame shows the actual status of the pipeline, showing which instruction is in which pipeline stage. Different colors highlight different pipeline stages.


The Memory frame shows memory cells content, along with labels and comments taken from the source code. Memory cells content, like registers, can be modified double-clicking on them, and clicking on them will show their decimal value in the status bar. The first column shows the hexadecimal address of the memory cell, and the second column shows the value of the cell. Other columns show additional info from the source code.


The Code window shows the instructions loaded in memory. The first column shows the address of the instruction, while the second column shows the hexadecimal representation of the instructions. Other columns show additional info taken from the source code.


The Input/Output window provides an interface for the user to see the output that the program creates through the SYSCALLs 4 and 5. Actually it is not used for input, as there’s a dialog that pops up when a SYSCALL 3 tries to read from standard input, but future versions will include an input text box.


Dialogs are used by EduMIPS64 to interact with the user in many ways. Here’s a summary of the most important dialogs:


In the Settings dialog various aspects of the simulator can be configured. Clicking on the “OK” button will cause the options to be saved, while clicking on “Cancel” (or simply closing the window) will cause the changes to be ignored. Don’t forget to click “OK” if you want to save your changes.

The Main Settings tab allow to configure forwarding and the number of steps in the Multi Cycle mode.

The Behavior tab allow to enable or disable warnings during the parsing phase, the “Sync graphics with CPU in multi-step execution” option, when checked, will synchronize the frames’ graphical status with the internal status of the simulator. This means that the simulation will be slower, but you’ll have an explicit graphical feedback of what is happening during the simulation. If this option is checked, the “Interval between cycles” option will influence how many milliseconds the simulator will wait before starting a new cycle. Those options are effective only when the simulation is run using the “Run” or the “Multi Cycle” options from the Execute menu.

The last two options set the behavior of the simulator when a synchronous exception is raised. If the “Mask synchronous exceptions” option is checked, the simulator will ignore any Division by zero or Integer overflow exception. If the “Terminate on synchronous exception” option is checked, the simulation will be halted if a synchronous exception is raised. Please note that if synchronous exceptions are masked, nothing will happen, even if the termination option is checked. If exceptions are not masked and the termination option is not checked, a dialog will pop out, but the simulation will go on as soon as the dialog is closed. If exceptions are not masked and the termination option is checked, the dialog will pop out, and the simulation will be stopped as soon as the dialog is closed.

The last tab allows to change the appearance of the user interface. There are options to change the colors associated to the different pipeline stages, an option to choose whether memory cells are shown as long or double values and an option to set the UI font size.

Note that the UI scaling with font size is far from perfect, but it should be enough to make the simulator usable with high-resolution displays (e.g., 4k).

Dinero Frontend

The Dinero Frontend dialog allows to feed a DineroIV process with the trace file internally generated by the execution of the program. In the first text box there is the path of the DineroIV executable, and in the second one there must be the parameters of DineroIV.

The lower section contains the output of the DineroIV process, from which you can take the data that you need.


The Help dialog brings up the on-line manual, which is an HTML copy of this document.

Command line options

Four command line options are available. They are described in the following list, with the long name enclosed in round brackets. Long and short names can be used in the same way.

  • -v (–version) prints the simulator version and exits.

  • -h (–help) prints a help message with a brief summary of command line options, then exits.

  • -f (–file) filename opens filename in the simulator

  • -r (–reset) resets the stored configuration to the default values

  • -d (–debug) enters Debug mode

  • -hl (–headless) Runs EduMIPS64 in headless mode (no gui)

The –debug flag has the effect to activate Debug mode. In this mode, a new frame is available, the Debug frame, and it shows the log of internal activities of EduMIPS64. It is not useful for the end user, it is meant to be used by EduMIPS64 developers.