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68 lines
3.6 KiB
HTML
68 lines
3.6 KiB
HTML
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<title>MARS 4.5 help contents
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<center>
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<h3>MARS - Mips Assembly and Runtime Simulator</h3>
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<h4>Release 4.5</h4>
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<h4>August 2014</h4>
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<h4>Operating Requirements</h4>
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<p>MARS is written in Java and
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requires at least Release 1.5 of the J2SE Java Runtime Environment (JRE) to work.
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The graphical IDE is implemented using Swing. It has been
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tested on Windows XP, Vista and 7; Mac OS X; and is also being used under Linux.
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<center>
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<h4>Some MARS Assembler and Simulator Limitations</h4>
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</center>
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Releases 3.0 and later assemble and simulate nearly all the MIPS32 instructions documented in the
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textbook <i>Computer Organization and Design, Fourth Edition</i> by Patterson and Hennessy,
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Elsevier - Morgan Kaufmann, 2009. All basic and pseudo instructions, directives,
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and system services described in Appendix B are implemented.
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<p>Limitations of MARS as of Release 4.5 include:
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<ul>
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<li>Memory segments (text, data, stack, kernel text, kernel data) are limited to 4MB each starting at their
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respective base addresses.</li>
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<li>There is no pipelined mode (but delayed branching is supported).</li>
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<li>If you open a file which is a link or shortcut to another file, MARS will <em>not</em>
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open the target file. The file open dialog is implemented using Java Swing's JFileChooser,
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which does not support links.</li>
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<li>Very few configuration changes, besides those in the Settings menu, are saved from one session to the next.
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The editor settings, which include font settings and display of line numbers, are saved.</li>
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<li>The IDE will work only with the MARS assembler. It cannot be used
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with any other compiler, assembler, or simulator. The MARS assembler and simulator
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can be used either through the IDE or from a command prompt.</li>
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<li><em>Bug:</em>The error message highlighter does not automatically select the code for the first assembly
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error if the file containing the error is not open at the time of assembly (assemble-on-open, assemble-all).</li>
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<li><em>Bug:</em> The Screen Magnifier screen capture feature does not appear to work properly under Windows Vista.</li>
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<li><em>Bug:</em> There appears to be a memory leak in the Editor. Several different people have independently
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reported the same behavior: severe slowdown in editor response during an extended interactive session.
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If MARS is exited and restarted, this behavior disappears and the editor responds instantly to actions.</li>
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<li><em>Not a bug, but documented here anyway:</em> MIPS Branch instruction target addresses are represented by
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the relative number of words to branch. With Release 3.4, this value reflects delayed branching,
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regardless of whether the Delayed Branching setting is enabled or not.
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The generated binary code for branches will now match that of examples in the <em>Computer Organization
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and Design</em> textbook. This is a change from the past, and was made after extensive discussions
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with several faculty adopters of MARS. Previously, the branch offset was 1 lower if the Delayed Branching setting
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was enabled -- the instruction <tt>label: beq $0,$0,label</tt> would generate <tt>0x1000FFFF</tt> if
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Delayed Branching was enabled and <tt>0x10000000</tt> if it was disabled. Now it will generate <tt>0x1000FFFF</tt> in
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either case. The simulator will always branch to the correct location; MARS does not allow assembly under one
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setting and simulation under the other to occur.</li>
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</ul>
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<p>
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<hr>
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<p>
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This document is available for printing on the MARS home page
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<tt><b>http://www.cs.missouristate.edu/MARS/</b></tt>.
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</body>
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</html> |