The memory viewer offers read and write access to all types of ROM and RAM:
Note: Only memory types that are available for the currently loaded ROM will be shown in the dropdown.
PRG ROM and CHR ROM are writable from the memory viewer. Any change will remain in effect until a power cycle. If you want to save your PRG/CHR ROM modifications to a .nes file, or as an IPS patch, you can use the File→Save or File→Save edits as IPS commands in the debugger window.
There are a number of highlighting/coloring options in the memory viewer.
View→Memory Access Highlighting has coloring options for addresses that were recently read, written or executed (colored in blue, red and green, respectively). A fade-out period can also be configured, after which the byte will revert to its normal black color.
View→Data Type Highlighting offers options to change the background color of specific bytes based on their type..
View→De-emphasize offers options to display bytes matching certain conditions (unused, read, written or executed) in gray.
Ignore writes that do not alter data option prevents CPU writes from being highlighted when the value being written matches the one already present in memory.
Note: It is possible to customize the colors used by the memory viewer in View→Configure Colors
There are 2 ways to edit memory values:
Using the hex view: Click on the byte you want to change in the hex view (on the left), and type hexadecimal values to replace it.
Using the text view: Click on the section you want to change in the text view (on the right), and type ASCII text to replace. This method is rather limited and usually not very useful unless the ROM uses ASCII values for its text.
For most types of memory, it is possible to export its contents to a binary file as well as import it back from a file. Use the
Export commands to do this.
Using the right-click menu, you can
Freeze values in CPU Memory. Frozen addresses are shown in magenta.
Frozen addresses will no longer be affected by write operations - effectively making those addresses read-only for the CPU. It is still possible to manually edit the value of frozen addresses using the memory viewer.
TBL files are text files that define mappings between sequences of bytes and text characters. For example, it might define the byte $95 as the character ‘A’.
Normally, when no TBL file is loaded, the memory viewer will display each byte’s standard ASCII representation on the right-hand side. Once a TBL file is loaded, the text representation of the data will be updated to reflect the TBL mappings. This is useful, for example, when translating text.
When active, the debugger keeps track of all CPU and PPU memory reads, writes and executions. It is possible to view these counters here.
Sort By option to sort the list based on different criteria.
Reset button allows you to reset all counters back to 0 – this is useful when you are trying to gather data for a specific portion of the execution.
Highlight uninitialized memory reads option to track down any reads done to RAM memory before the RAM memory has been initialized after a power cycle – reading from uninitialized memory can produce random behavior, which is usually unwanted.
The profiler automatically collects data about all function calls done by the code, as well as the number of clock cycles spent in each respective function.
Using the profiler makes it is easy to find the bottlenecks in a game’s code, which can help code optimization efforts.
If you are familiar with Visual Studio’s profiler, these columns should be familiar:
Reset button to reset the profiler’s data – use this when you want to profile a specific portion of the execution.