| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960 |
- <html>
- <head>
- <title>Pop-up menus and files</title>
- </head>
- <body bgcolor="FFFFFF">
- <h1>Pop-up menus and files</h1>
- <p>The pop-up menu for memory includes four options in addition
- to the options common to all components:</p>
- <ul>
- <li>Edit Contents: Bring up a hex editor for editing the contents
- of memory.</li>
- <li>Clear Contents: Resets all values in memory to 0.</li>
- <li>Load Image...: Resets all values in memory based on the values
- found in a file using the format described below.</li>
- <li>Save Image...: Stores all values in memory into a file using
- the format described below.</li>
- </ul>
- <p>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.</p>
- <blockquote><pre>
- v2.0 raw
- 02
- 03
- 00
- 14
- ff
- </pre></blockquote>
- <p>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. If there are more memory locations than are identified
- in the file, Logisim will load 0 into the other memory locations.</p>
- <p>The image file can use run-length encoding; for example, rather than
- list the value <tt>00</tt> sixteen times in a row, the file can include
- <tt>16*00</tt>. 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.</p>
- <p>You can place comments into the file by using the '#' symbol: All characters
- in the line starting from the '#' symbol will be ignored by Logisim.</p>
- <p><strong>Next:</strong> <a href="hex.html">Hex editor</a>.</p>
- </body>
- </html>
|
