To open a ROM file, select 'Open ROM File…' from the 'File' menu, and select the ROM file that you wish to use:

After a ROM file has been opened once, its filename is remembered for later. This allows the file to be quickly re-opened from the 'Reopen ROM File' submenu
This submenu will hold a maximum of ten (10) previously opened files. This can be very helpful in making new files quickly by using data from ROM files that you have previously created.
Once a ROM file has been selected and opened, the ROM editor window will be displayed.
NOTE: Windows 7 will also show the last opened ROMs in the taskbar:

A single ROM file is presented as a number of maps. These maps contain the data that the ECU uses to choose values for engine parameters such as ignition timing, fuelling and rev limiting. The different types of map within each ECU ROM file are described below:

As confidence is gained with the software, and the tuner wishes to investigate more advanced maps, the user level of the software may be changed as shown below. Simply put, the higher the user level selected, the larger the number of maps that are displayed.
Note that the number of maps displayed only changes on ROMs that are opened after changing the user level. Views of currently open ROM files will not change until the ROM file is closed and then re-opened.

At this point, it is worth mentioning interpolation. It is rare for the input to a 2D or 3D map to exactly match one of the scale values. If the input value exactly matches a scale value, then the corresponding output value is the result. However this does not often happen – it is more likely that the input value will lie somewhere between two of the scale values.
Interpolation smoothes out sharp steps between map values and allows smaller numbers of rows and columns to be used, reducing map size and complexity for editing.

Like 2D Maps consist of a table of values. However, 3D maps are different because they may have any number of rows and columns. This is because the output value of a 3D maps is based on two inputs rather than one. A good example of a 3D maps is the high octane ignition map. The ignition timing used is based on engine RPM and also on engine load

The input values of a 3D map are known as scale data. A 3D map has both an X and a Y scale. The ECU uses the X & Y scales to determine from which row and column intersections a data value will be retrieved.
Typically the scales are engine load across the top left to right and RPM at the side from top to bottom.

The output values of a 3D map are known as the map data. The map data always has the number of rows and columns to equal the X and Y scales. Each value within the map data is known as a zone.

2D Maps consist of a table of input and output values. The ECU uses an engine parameter, such as current Engine RPM, to choose a value from the map. I.e. based on the input value, one of the output values is chosen. A 2D map always has 2 rows, but may have very many columns. A good example of a 2D map is the ECU's boost limit map. The boost limit (sometimes called Fuel Cut) varies according Engine RPM and is based against Engine Load (similar to Airflow). The current Boost Limit is relative to the current Engine RPM.

The input values of a 2D map are known as the scale data. This is the left row of values (shaded in grey). The ECU uses the scale data to choose from which columns the output value will be retrieved.

The output values of a 2D map are known as the map data. This is the right row of values (no shading).
Example:
The Scale Data values are required so the ECU can choose the correct Map Data. So at 1600 RPM we can see the Boost Limit is 1.35 bar.

These are the simplest of maps. They contain 1 or more fixed values that the ECU uses. A good example of this is the Rev Limit map. This map consists of a single data value at which the ECU will cut the fuel injectors.

Values in the maps are shown are all real values so an Ignition table is filled with true Ignition degrees Before TDC. A minus value (-5) shows an Ignition value after TDC.

To select a data point, simply click on that point using the mouse. The map value of the selected zone will be highlighted and displayed just above the top right of the map. Once a zone is selected the cursor keys can be used to move around the map to view values in other zones. You can also select an area of a map by using the standard windows function of 'Click and Hold' then moving the mouse.

All 3D maps are coloured by default. The colouring can be changed using the 'View' menu by selecting 'Clear Colouring'.
After changing a value or several values always choose 'View' and 'Show Map Coloured' to see a possible error in your changes. The 'Show Map Coloured' can quickly show errors if the colouring has been turned off, as shown below:

The graphing can be turned off from the main ProECU under the 'Options' menu:

Maps can be viewed graphically by clicking on the 'plot' menu of any map. This brings up a plot of the map. Every zone of the map will be plotted on the chart. This gives a 'contour' view of the map. The colours of the table are represented in the same area on the graph.
Clicking on or near any data point on the chart will highlight that value, both on the chart and on the map data. Again, cursor keys can be used to move around the map.

Resizing
3D and 2D Maps may also be resized using the usual Windows function of resizing by grabbing the edge of the window to allow high resolution viewing of Graphs.