The file format used for image files is intentionally simple; this permits you to write a program, such as an assembler, that generates memory images that can then be loaded into memory. As an example of this file format, if we had a 256-byte memory whose first five bytes were 2, 3, 0, 20, and -1, and all subsequent values were 0, then the image would be the following text file.
02 03 00 14 ff
The first line identifies the file format used (currently, there is only one file format recognized). Subsequent values list the values in hexadecimal, starting from address 0; you can place several such values on the same line. Logisim will assume that any values unlisted in the file are zero.
The image file can use run-length encoding; for example, rather than list the value 00 sixteen times in a row, the file can include 16*00 rather than repeat 00 sixteen times. Notice than the number of repetitions is written in base 10. Files produced by Logisim will use run-length encoding for runs of at least four values
In general, binary data will expand in sized by approximately 2.95 times when represented with this format.
This format is particularly deficient.
- The is no way for changing address in-flight. And therefore the format can't have holes in the data.
- There are no checksums, or any other error checking.
- There is no provision for a comment header, as distinct to the “v2.0 raw” magic number.
- There is no provision for an execution start adddress.
srec_logisim.5 version 1.64
Copyright © 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 Peter Miller
The srec_logisim.5 program comes with ABSOLUTELY NO WARRANTY; for details use the 'srec_logisim.5 -VERSion License' command. This is free software and you are welcome to redistribute it under certain conditions; for details use the 'srec_logisim.5 -VERSion License' command.