SIC/XE Reference support page: COP 3601, Fall, 2006 - Charles Winton

<body text="#000000" background="../../../gif/background.gif" link="#000099" vlink="#990099" alink="#0000FF">  <table width="95%" align=center><tr><td> <center><img src="../../../gif/COP3601.gif"></center>   <table align=center border=0 cellpadding=0 cellspacing=0 background="../../../gif/background.gif" width=638> <tr><td>  <table align=center border=0 cellpadding=0 cellspacing=0 background><tr>     <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <a href="../f06/3601menu.html" class="bkcolor" onclick="window.location='../f06/3601menu.html'"> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="../f06/3601menu.html" class="bkcolor">  <font size=1>  Course  <br>  Menu   </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <a href="../f06/description.html" class="bkcolor" onclick="window.location='../f06/description.html'"> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="../f06/description.html" class="bkcolor">  <font size=1>  Course  <br> Description  </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <a href="../f06/outline.html" class="bkcolor" onclick="window.location='../f06/outline.html'"> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="../f06/outline.html" class="bkcolor">  <font size=1>  Course  <br>  Outline   </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <a href="../f06/assignments.html" class="bkcolor" onclick="window.location='../f06/assignments.html'"> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="../f06/assignments.html" class="bkcolor">  <font size=1> Assignments <br> & Doc Specs  </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <a href="../supplements/3601tools.html" class="bkcolor" onclick="window.location='../supplements/3601tools.html'"> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="../supplements/3601tools.html" class="bkcolor">  <font size=1>  Software  <br>  Summary   </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="pseudocode.html" class="bkcolor" onclick="st=self.screenTop; sl=self.screenLeft; newpg=window.open('../f06/class.notes/title-pg.pdf'); newpg.moveTo(0,st);">  <font size=1>  Class  <br>  Notes   </a> </td></tr></table> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EBFFFF" bordercolorlight="#000000" bordercolordark="#5588AA" bordercolor="#000000" align=center><tr><td>  <table cellspacing=0 cellpadding=0><tr><td width=65 align=center>   <font size=1 color=blue><b> Pseudocode <br>  Modules  </b> </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <a href="sicsim.page.html" class="bkcolor" onclick="window.location='sicsim.page.html'"> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="sicsim.page.html" class="bkcolor">  <font size=1>  SIC/XE  <br>  Reference   </a> </td></tr></table> </a> </td></tr></table> </td> <td><font size=1> <table border=5 BGcolor="#EEEEEE" align=center><tr><td> <table cellspacing=0 cellpadding=0><tr><td width=65 align=center> <a href="sicsim.page.html" class="bkcolor" target="_top" onclick="st=self.screenTop; sl=self.screenLeft; newpg=window.open('sys-supp.pdf'); newpg.moveTo(0,st);">  <font size=1> Course  <br> Supplement  </a> </td></tr></table> </td></tr></table> </td> </tr></table>  <br> <table align=center width="95%" cellspacing=5> <tr><td align=center><font size=+2>Using the UNF Implementation of the</font></td></tr> <tr><td align=center><font size=+3>SIC/XE Simulator</font><a href="sicsim.docL.html">.</a></td></tr> </table> <br> <table align=center width="95%" border=5 background="../../../gif/marblefaint.jpg"><tr><td> <table align=center width="95%"><tr><td> <br>  <a name="Intro"></a> <ol type=1><b><font size=+1><li>Introduction/Simulator Commands</b></font> <p> SIC (Simplified Instructional Computer) is a machine designed to illustrate the most commonly encountered computer hardware features and concepts, while avoiding most of the idiosyncracies that are often found in real machines. There is an enhanced version of the machine (SIC/XE), that includes additional features (more addressing modes, floating point instructions, interrupts, virtual memory and memory protection features). A complete description of SIC and SIC/XE is contained in <I>System Software: An Introduction to Systems Programming</I> by Beck (Addison-Wesley). <p> At UNF, a partial implementation of SIC/XE is provided via a modified version of a SIC/XE simulator originated by Beck. It is installed on the UNF Osprey Unix system. The simulator includes some (but not all) of the SIC/XE features. <p> Once logged onto the system under UNIX the SIC simulator is started by entering <p> <font face="Courier" color=blue>     sicsim</font> <p> The simulator will display <PRE><font color=red> SIC SIMULATOR V1.6 File names are: DEV00 DEVF1 DEVF2 DEVF3 DEV04 DEV05 DEV06 COMMAND: A(CCEPT file names, R(ENAME 1 or more files </font></PRE> <p> Section 2 (I/O Device Conventions) describes the function of each of these files. By entering <font face="Courier" color=blue>RENAME</font> (or <font face="Courier" color=blue>R</font>) you will be able to alter any of the above (default) file names to correspond to the file names you have decided to use. A null return on any file name prompt leaves it unchanged. The file name list and prompt is repeated until you enter the command <font face="Courier" color=blue>ACCEPT</font> (or <font face="Courier" color=blue>A</font>). At this point the primary command line <pre><font color=red>COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT?</font></pre> <p> is displayed. You may enter any of the commands described below; each command may be abbreviated by entering only its first letter. <p> <b><font color=blue>START</font></b> <p> Entering <font face="Courier" color=blue>S</font> causes the simulator to read 128 bytes of data from device <font face="Courier" color=blue>00</font> (default file name <font face="Courier" color=blue>DEV00</font>) into memory, starting at address <font face="Courier" color=blue>0000</font>. This command would normally be used to bootstrap a loader or other program into memory. See the section "I/O Device Conventions" below for further information. <p> <b><font color=blue>RUN</font></b> <p> This command causes the simulator to begin executing SIC machine language instructions from a program in memory. There are two forms of the command: <pre><font color=blue> R R <font color=black><<font face="Times" size=3><i>address</i></font>></font></font></pre> <p> If an address is specified in the command, the next instruction to be executed is the one starting at that address. (All addresses specified in commands are given in hexadecimal.) If no address is specified, the next instruction to be executed is the one following the last previously-executed instruction, if any, or the instruction beginning at address <font face="Courier" color=blue>0000</font>. Execution continues until an error occurs, or the number of instructions specified by <font face="Courier" color=blue>HCOUNT</font> has been executed, or a breakpoint specified by <font face="Courier" color=blue>BKPT</font> is reached (see below). <p> <b><font color=blue>ENTER</font></b> <p> This command is used to enter values into registers or memory locations. The two possible forms of the command are <pre><font color=blue> E R<font color=black><<font face="Times" size=3><i>reg-id</i></font>></font> xxxxxx E <font color=black><<font face="Times" size=3><i>address</i></font>></font> xxxx...</font></pre> <p> In the first case, <font face="Courier" color=blue>R<font color=black><</font></font><i>reg-id</i><font face="Courier">></font> is a register identifier (<font face="Courier" color=blue>RA, RX, RL, RB, RS, RT</font>). Data to be entered into the register is given in hexadecimal notation, with two hexadecimal digits specifying each byte of data. When entering data into a register, exactly three bytes (6 hex digits) must be given. <p> In the second case, any number of bytes of data may be entered into memory, starting at the address specified. Each byte of data to be entered is specified with two hexadecimal digits, as above. <p> <b><font color=blue>DUMP</font></b> <p> This command is used to display the contents of registers and memory locations. There are three possible forms of the command: <pre><font color=blue> D R D <font color=black><<font face="Times" size=3><i>startaddr</i></font>><font color=blue>-</font><<font face="Times" size=3><i>endaddr</i></font>></font> D R,<font color=black><<font face="Times" size=3><i>startaddr</i></font>><font color=blue>-</font><<font face="Times" size=3><i>endaddr</i></font>></font></font></pre> <p> If <font face="Courier" color=blue>R</font> is specified, the contents of all registers are displayed in hexadecimal, along with the current value of the condition code. If <i>startaddr</i> and <i>endaddr</i> are specified, the contents of the indicated range of address are displayed; a maximum of 320 (decimal) bytes can be dumped at one time. Because memory is displayed in rows of 16 bytes each, the actual dump may include some bytes before <i>startaddr</i> and some bytes after <i>endaddr</i>. <p> <b><font color=blue>HCOUNT</font></b> <p> This command is used to specify the maximum number of SIC instructions to be executed in response to a <font face="Courier" color=blue>RUN</font> command. This limit allows the user to regain control in the case there is an unending loop in the program being simulated. The command has the form <pre><font color=blue> H <font color=black><<font face="Times" size=3><i>nmbr</i></font>></font></font></pre> <p> where <i>nmbr</i> is a value given by 1 to 4 decimal digits. The maximum value that can be specified is <font face="Courier" color=blue>9999</font>; if no <font face="Courier" color=blue>HCOUNT</font> command is entered, the default value is <font face="Courier" color=blue>1000</font>. An <font face="Courier" color=blue>HCOUNT</font> of <font face="Courier" color=blue>1</font> allows the program to be "single-stepped". <p> After <i>n</i> instructions have been executed, the simulator displays <pre> <font color=blue><<font face="Times" size=3><i>nmbr</i></font>></font><font color=red> INSTRUCTIONS EXECUTED</font> <font color=red>P=</font><font color=blue>xxxxxx</font></pre> <p> where <font face="Courier" color=blue>xxxxxx</font> is the current program counter value (i.e., the address of the next instruction to be executed). Entering <font face="Courier" color=blue>RUN</font> as the next command will resume execution at this point (for another <i>nmbr</i> instructions). <p> <b><font color=blue>BKPT</font></b> <p> This command is used to set a breakpoint to control instruction execution. The form of the command is <pre><font color=blue> B</font> <<font face="Times" size=3><i>address</i></font>></pre> <p> When the next instruction to be executed begins at the specified address, the simulator displays <pre><font color=red> BREAKPOINT REACHED P=</font><font color=blue>xxxxxx</font></pre> <p> where <font face="Courier" color=blue>xxxxxx</font> is the current location counter value (i.e., the breakpoint address). Entering <font face="Courier" color=blue>RUN</font> as the next command will resume execution at this point. <p> <b><font color=blue>FILES</font></b> <p> This command reactivates the <font face="Courier" color=blue>ACCEPT/RENAME</font> procedure for file names described earlier. <p> <b><font color=blue>TRACE</font></b> <p> This command initiates a display of the last 10 instructions executed. <p> <b><font color=blue>QUIT</font></b> <p> This command is used to terminate simulation. <p>  <a name="IODevices"></a> <b><font size=+1><li>I/O Device Conventions</b></font> <p> Device <font face="Courier" color=blue>00</font> (default file name <font face="Courier" color=blue>DEV00</font>) is used only by the <font face="Courier" color=blue>START</font> command; it contains 128 bytes of bootstrap data, represented with two hexadecimal digits (characters <font face="Courier" color=blue>0-9</font> and <font face="Courier" color=blue>A-F</font>) per byte. For ease of creation and editing, this file is represented as a text file with four lines of data; each line contains 64 characters (which represent 32 bytes of data). In other words, this file can be created using any of the text editors under UNIX (e.g., "<font face="Courier" color=blue>ex</font>", "<font face="Courier" color=blue>vi</font>" or "<font face="Courier" color=blue>ed</font>"). <p> A device <font face="Courier" color=blue>00</font> loader (described further below), stored in the file "<font face="Courier" color=blue>loader</font>" (which must be used in place of the default file "<font face="Courier" color=blue>DEV00</font>") is supplied for use by COP 3601 students. This loader will handle a <b>text</b> file of hexadecimal digits (such as created under "<font face="Courier" color=blue>ex</font>", "<font face="Courier" color=blue>vi</font>" or "<font face="Courier" color=blue>ed</font>") , converting them to true numeric form and storing them 2 hex digits per byte in SIC memory. The device <font face="Courier" color=blue>F1</font> file (default file name <font face="Courier" color=blue>DEVF1</font>) is used to provide the input to this loader. <p> The simulator supports six simulated SIC devices for use by the program: devices <font face="Courier" color=blue>F1</font>, <font face="Courier" color=blue>F2</font>, and <font face="Courier" color=blue>F3</font> (default file names <font face="Courier" color=blue>DEVF1</font>, <font face="Courier" color=blue>DEVF2</font>, and <font face="Courier" color=blue>DEVF3</font>), which can be used only for input, and devices <font face="Courier" color=blue>04</font>, <font face="Courier" color=blue>05</font>, and <font face="Courier" color=blue>06</font> (default file names <font face="Courier" color=blue>DEV04</font>, <font face="Courier" color=blue>DEV05</font>, and <font face="Courier" color=blue>DEV06</font>), which can be used only for output. For any of these files, each byte of data is represented as one character. On input, an end-of-line is read as hexadecimal <font face="Courier" color=blue>0A</font>; and end-of-file is read as hexadecimal <font face="Courier" color=blue>04</font>. On output, writing a hexadecimal <font face="Courier" color=blue>0A</font> causes an end-of-line to be inserted. <p> Device timing delays are simulated via the <font face="Courier" color=blue>TD</font> instruction. Except for the first time the device is addressed, a <font face="Courier" color=blue>TD</font> (Test Device) issued to a device will return the "<font color=red>device busy</font>" indication from 1 to 4 times before signalling "<font color=red>device ready</font>". An attempt to execute an <font face="Courier" color=blue>RD</font> or <font face="Courier" color=blue>WD</font> instruction before the device is ready will cause an error message. <p>  <a name="Notes"></a> <b><font size=+1><li>Notes</b></font> <p> <ol> <li>The largest main memory address is <font face="Courier" color=blue>2FFF</font>. When the simulator is initialized, all registers are set to <font face="Courier" color=blue>FFFFFF</font> and all memory locations are set to <font face="Courier" color=blue>FF</font>. <p> <li>The file "<font face="Courier" color=blue>sic.log</font>" contains a listing of all terminal input and output for the simulation run. This file may be printed to obtain a hard-copy record of the simulation. <p> <li>When the simulator detects a run-time error (for example, illegal machine instruction, address out of range, or arithmetic overflow) it displays an error message and the current program counter value. This value will be either the address of the instruction that caused the error, or the address of the next instruction following it (depending upon the type of error detected). </ol> <p>  <a name="Limitations"></a> <b><font size=+1><li>Limitations</b></font> <p> This version of the simulator supports all SIC/XE instructions and features except for the following: <ol> <li>Floating-point data type and associated instructions (<font face="Courier" color=blue>ADDF</font>, <font face="Courier" color=blue>SUBF</font>, <font face="Courier" color=blue>MULF</font>, <font face="Courier" color=blue>DIVF</font>, <font face="Courier" color=blue>COMPF</font>, <font face="Courier" color=blue>LDF</font>, <font face="Courier" color=blue>STF</font>, <font face="Courier" color=blue>FIX</font>, <font face="Courier" color=blue>FLOAT</font>, <font face="Courier" color=blue>NORM</font>) <p> <li>I/O channels and associated instructions (<font face="Courier" color=blue>SIO</font>, <font face="Courier" color=blue>HIO</font>, <font face="Courier" color=blue>TIO</font>) <p> <li>Interrupts and associated instructions (<font face="Courier" color=blue>LPS</font>, <font face="Courier" color=blue>STI</font>, <font face="Courier" color=blue>STSW</font>, <font face="Courier" color=blue>SVC</font>) <p> <li>Register <font face="Courier" color=blue>SW</font> and associated features (user/supervisor modes, running/idle states) <p> <li>Virtual memory and memory protection </ol> <p>  <a name="Session"></a> <b><font size=+1><li>Example Session</b></font> <p> Consider the following example program: <PRE><font color=red>loc code EXAMPLE START 100 0100 01000C LDA #12 . LOAD 12 INTO REG A 0103 190007 ADD #7 . ADD 7 TO REG A 0106 0F2003 STA SAVA . STORE A IN MEMORY 0109 4F0000 RSUB . RETURN 010C SAVA RESW 1 END EXAMPLE </font></PRE> <p> Assume the code is stored in the UNIX file "<font face="Courier" color=blue>DEVF1</font>" as follows: <pre> <font color=blue>000100</font> <font face="Times", size=3><<< <i>load point</i></font> <font color=blue>000100</font> <font face="Times", size=3><<< <i>starting address</i></font> <font color=blue>01000C</font> <font face="Times", size=3><<< <i>first line of code</i></font> <font color=blue>190007</font> <font color=blue>0F2003</font> <font color=blue>4F0000</font> <font face="Times", size=3><<< <i>last line of code</i></font> <font color=blue>!</font> <font face="Times", size=3><<< <i>code delimiter</i></font> </PRE> <p> A terminal session to execute this code on the SIC simulator might generate the following "<font face="Courier" color=blue>sic.log</font>" file (a facsimile generated by the UNIX command "<font face="Courier" color=blue>cat sic.log</font>" with annotations later added inside []; see note 2 in Section 3 (Notes)). The loader file which replaces the default file "<font face="Courier" color=blue>DEV00</font>" is described in Section 6 (SIC/XE Loader). <pre><font color=red>$sicsim SIC SIMULATOR V1.6 File names are: DEV00 DEVF1 DEVF2 DEVF3 DEV04 DEV05 DEV06 COMMAND: A(CCEPT file names, R(ENAME 1 or more files r <font face="Times" color=black size=3>[<<<</font><font color=blue> r </font><font face="Times" color=black size=3><i>entered to prompt renaming</i>]</font> DEV00 loader <font face="Times" color=black size=3>[<<< <i>system boot redirected to the file</i> "</font><font color=blue>loader</font><font face="Times" color=black size=3>"]</font> DEVF1 <font face="Times" color=black size=3>[<<< <i>null response (so file remains</i></font><font color=blue> DEVF1</font><font face="Times" color=black size=3>)]</font> DEVF2 <font face="Times" color=black size=3>[<<< <i>null response (so file remains</i></font><font color=blue> DEVF2</font><font face="Times" color=black size=3>)]</font> DEVF3 <font face="Times" color=black size=3>[<<< <i>null response (so file remains</i></font><font color=blue> DEVF3</font><font face="Times" color=black size=3>)]</font> DEV04 <font face="Times" color=black size=3>[<<< <i>null response (so file remains</i></font><font color=blue> DEV04</font><font face="Times" color=black size=3>)]</font> DEV05 <font face="Times" color=black size=3>[<<< <i>null response (so file remains</i></font><font color=blue> DEV05</font><font face="Times" color=black size=3>)]</font> DEV06 <font face="Times" color=black size=3>[<<< <i>null response (so file remains</i></font><font color=blue> DEV06</font><font face="Times" color=black size=3>)]</font> File names are: loader DEVF1 DEVF2 DEVF3 DEV04 DEV05 DEV06 COMMAND: A(CCEPT file names, R(ENAME 1 or more files a <font face="Times" color=black size=3>[<<< "</font><font color=blue>a</font><font face="Times" color=black size=3>" <i>entered to operate with these files</i>]</font> COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? d r,0-2f <font face="Times" color=black size=3>[<<< <i>dump of registers and memory</i></font><font color=blue> 0000 </font><font face="Times" color=black size=3><i>through</i></font><font color=blue> 002F</font><font face="Times" color=black size=3>]</font> A=FFFFFF X=FFFFFF L=FFFFFF B=FFFFFF S=FFFFFF T=FFFFFF P=000000 CC=LT 0000 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 0010 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 0020 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? s <font face="Times" color=black size=3>[<<< "</font><font color=blue>s</font><font face="Times" color=black size=3>" <i>entered to load the boot file</i> (<font color=blue>loader</font>)]</font> COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? d r,0-7f <font face="Times" color=black size=3>[<<< <i>dump to show the boot file is now in memory</i>]</font> A=FFFFFF X=FFFFFF L=FFFFFF B=FFFFFF S=FFFFFF T=FFFFFF P=000000 CC=LT 0000 B4104B20 2F572071 4B202957 206C4B20 0010 23572067 6B20624B 201A5720 5C4B2014 0020 5720574B 200E5720 524B2008 57C000B8 0030 103F2FF5 1720454B 200EA403 5720404B 0040 20064720 383E2034 E100F133 2FFAB400 0050 D900F129 00303B20 0F1D0030 29000A3B 0060 20031D00 074F0000 29002133 20062900 0070 04372FD4 B4203E20 00FFFFFF FFFFFFFF COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? b 109 <font face="Times" color=black size=3>[<<< <i>break point to stop program prior to executing</i></font><font color=blue> RSUB</font><font face="Times" color=black size=3>]</font> COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? r <font face="Times" color=black size=3>[<<< "</font><font color=blue>r</font><font face="Times" color=black size=3>" <i>entered to initiate execution (from</i></font><font color=blue> PC=000000</font><font face="Times" color=black size=3>)]</font> BREAKPOINT REACHED <font face="Times" color=black size=3>[<i>loader has finished and turned execution over to loaded</i>]</font> P=000109 <font face="Times" color=black size=3>[<i>program which has executed through location</i></font><font color=blue> 106</font><font face="Times" color=black size=3>]</font> COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? t <font face="Times" color=black size=3>[<<< "</font><font color=blue>t</font><font face="Times" color=black size=3>" entered to show last 10 instructions executed]</font> Trace of last 10 instructions executed PC Instruction <font face="Times" color=black size=3>[<i>assembly code from section 7 and program above</i>]</font> 000050 D900F1 <font face="Times" color=black size=3>[</font><font color=blue>RD #X'F1'</font><font face="Times" color=black size=3>]</font> 000053 290030 <font face="Times" color=black size=3>[</font><font color=blue>COMP #48</font><font face="Times" color=black size=3>]</font> 000056 3B200F <font face="Times" color=black size=3>[</font><font color=blue>JLT EOFCK </font><font face="Times" color=black size=3><<< <i>branch taken to</i> </font><font color=blue>68=59+F</font><font face="Times" color=black size=3>]</font> 000068 290021 <font face="Times" color=black size=3>[</font><font color=blue>COMP #33</font><font face="Times" color=black size=3>]</font> 00006B 332006 <font face="Times" color=black size=3>[</font><font color=blue>JEQ EXIT </font><font face="Times" color=black size=3><<< <i>branch taken to</i> </font><font color=blue></font><font color=blue>74=6E+6</font><font face="Times" color=black size=3>]</font> 000074 B420 <font face="Times" color=black size=3>[</font><font color=blue>CLEAR L</font><font face="Times" color=black size=3>]</font> 000076 3E2000 <font face="Times" color=black size=3>[</font><font color=blue>J @ADDR </font><font face="Times" color=black size=3><<< <i>branch taken to address stored at</i> </font><font color=blue>79</font><font face="Times" color=black size=3>]</font> 000100 01000C <font face="Times" color=black size=3>[</font><font color=blue>LDA #12</font><font face="Times" color=black size=3>]</font> 000103 190007 <font face="Times" color=black size=3>[</font><font color=blue>ADD #7</font><font face="Times" color=black size=3>]</font> 000106 0F2003 <font face="Times" color=black size=3>[</font><font color=blue>STA SAVA</font><font face="Times" color=black size=3>]</font> COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? d 100-110 <font face="Times" color=black size=3>[<<< <i>dump of the section of memory holding the loaded code</i>]</font> <font face="Times" color=black size=3>[<i>result boldfaced</i>]</font> 0100 01000C19 00070F20 034F0000 <b>000013</b>FF 0110 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? r <font face="Times" color=black size=3>[<<< "</font><font color=blue>r</font><font face="Times" color=black size=3>" <i>entered to continue execution</i>]</font> ATTEMPT TO READ DEVF1 PAST END OF FILE P=000053 <font face="Times" color=black size=3>[<i>loaded program once done returns control to the loader</i>]</font> <font face="Times" color=black size=3>[<i>which attempts to load the next one (it's not there!)</i>]</font> COMMAND: S(TART, R(UN, E(NTER, D(UMP, H(COUNT, B(KPT, F(ILES, T(RACE, Q(UIT? q <font face="Times" color=black size=3>[<<< "</font><font color=blue>q</font><font face="Times" color=black size=3>" <i>entered to end simulation and finalize</i> <font face="Times" color=black size=3> "</font><font color=blue>sic.log</font><font face="Times" color=black size=3>"]</font> </font></font></pre> <p>  <a name="Loader"></a> <b><font size=+1><li>SIC/XE Loader</b></font> <p> The SIC/XE loader is a 128 character SIC/XE program designed to fit in the 128 character boot file space. It is composed of fully relocatable code. The loader is designed to input a load module of hex characters from a text file, converting them to true numeric form, and storing them beginning from a specified load point. At the end of the load, control is passed to a specified starting address. <p> <b>Load module file format</b> <p> A text file of hex characters as follows: <ol> <p> <li>1st 6 characters = load point <p> <li>Next 6 characters = address to receive control when load is finished ("<font face="Courier" color=blue>000000</font>" to re-run the loader and input the next module - see below) <p> <li>Rest of file = code to be stored in memory beginning from the load point <p> <li>Module delimiter = <font face="Courier" color=blue>!</font> </ol> <p> <b>Restrictions</b> <ol> <li>The loader input is via device <font face="Courier" color=blue>F1</font> (default file name <font face="Courier" color=blue>DEVF1</font>) <p> <li>The loader is stored in the file "<font face="Courier" color=blue>loader</font>". The SIC simulator will boot from this file under the <font face="Courier" color=blue>START</font> command if the default file name for device <font face="Courier" color=blue>00</font> (<font face="Courier" color=blue>DEV00</font>) is replaced by the file name "<font face="Courier" color=blue>loader</font>". <p> <li>The load point must be greater than <font face="Courier" color=blue>X'00007F'</font> <p> <li>The loader does no error checking for validity of input </ol> <p> <b>Normal object code layout for use by loader</b> <p> Each load module normally consists only of actual code. In particular, the storage directives <font face="Courier" color=blue>RESW</font> and <font face="Courier" color=blue>RESB</font> have no corresponding code and so typically provide a natural point at which to terminate a load module (alternately, garbage could be inserted into the code to reserve the needed amount of storage). If more than one load module is employed for a program, then the loader must be restarted for each load module. This is done by putting the loader start address (<font face="Courier" color=blue>000000</font>) as the start address component for each load module except the last one. The last load module has the start address for the full program in its start address component. For example, the code <pre><font color=red>loc code EXAMPLE START 100 0100 01000C LDA #12 . LOAD 12 INTO REG A 0103 190007 ADD #7 . ADD 7 TO REG A 0106 0F2003 J STORE . STORE A IN MEMORY 0109 SAVA RESW 10 0127 0F2FDF STORE STA SAVA 012A 4F0000 RSUB . RETURN END EXAMPLE </font></pre> <p> could be set up for the loader as <pre><font color=blue> 000100 <font face="Times" color=black size=3><<< <i>load point for the first module</i></font> 000000 <font face="Times" color=black size=3><<< <i><b>start address of loader</b> (gets next module loaded)</i></font> 01000C <font face="Times" color=black size=3><<< <i>first line of code for this module</i></font> 190007 0F2003 ! <font face="Times" color=black size=3><<< <i>end of the first module</i></font> 000127 <font face="Times" color=black size=3><<< <i>load point for the second module</i></font> 000100 <font face="Times" color=black size=3><<< <i><b>start address of the program</b> (no more to load)</i></font> 0F2FDF <font face="Times" color=black size=3><<< <i>first line of code for this module</i></font> 4F0000 ! <font face="Times" color=black size=3><<< <i>end of the second module</i></font> </pre> <font color=black>or alternately as the single module</font><pre> 000100 <font face="Times" color=black size=3><<< <i>load point for the first module</i></font> 000100 <font face="Times" color=black size=3><<< <i>start address of program</i></font> 01000C <font face="Times" color=black size=3><<< <i>first line of code for this module</i></font> 190007 0F2003 FFFFFFFFFFFFFFFF <font face="Times" color=black size=3><<< 30 <i>garbage bytes</i></font> FFFFFFFFFFFFFFFF FFFFFFFFFFFFFFFF FFFFFFFFFFFF 0F2FDF 4F0000 ! <font face="Times" color=black size=3><<< <i>end of module</i></font> </font></pre> <p><b>Loader algorithm</b> <pre> <font color=blue>PROCEDURE</font> SICloader <font color=blue>INTEGER</font> loadpt, startaddr, i { <font color=blue>i</font> <i>implemented via registers</i> <font color=blue>B + X</font> } <font color=blue>CHARACTER</font> ascii { <font color=blue>ascii</font> <i>implemented via register</i> <font color=blue>A</font> } <font color=blue>HEXDIGIT</font> hex <font color=blue>LOOP</font> <font color=green><b>Get</b></font>(loadpt) { 3 <i>calls to</i> "<font color=blue>GETPAIR</font>" } i = loadpt <font color=green><b>Get</b></font>(startaddr) { 3 <i>more calls to</i> "<font color=blue>GETPAIR</font>" } <font color=blue>LOOP</font> { "<font color=blue>GETPAIR</font>" <i>strategy</i> } <font color=green><b>Input</b></font>(ascii) <font color=blue>IF</font> ascii < '0' <font color=blue>THEN</font> <font color=blue>IF</font> ascii = '!' <font color=blue>THEN</font> <font color=blue>EXIT</font> <font color=blue>ENDIF</font> <font color=blue>ELSE</font> hex = <font color=green><b>Hexconvert</b></font>(ascii) { <i>convert</i> ASCII <i>representation by</i> } <font color=green><b>Input</b></font>(ascii) { <i>subtracting down to range</i> <font color=blue>0..F</font> } <font color=blue>IF</font> ascii < '0' <font color=blue>THEN</font> <font color=blue>IF</font> ascii = '!' <font color=blue>THEN</font> <font color=blue>EXIT</font> <font color=blue>ENDIF</font> <font color=blue>ENDIF</font> <font color=blue>ENDIF</font> MEMORY[i] = <font color=green><b>Hexpair</b></font>(hex, <font color=green><b>Hexconvert</b></font>(ascii)) i = i + 1 { <i>store the</i> 8 <i>bit pair formed from</i> } { "<font color=blue>hex</font>" <i>and the one converted from</i> } { "<font color=blue>ascii</font>" <i>into memory location</i> <font color=blue>i</font> } <font color=blue>REPEAT</font> <font color=blue>CALL</font> loadpt <font color=blue>REPEAT</font> <font color=blue>END</font> SICloader </pre> <p>  <a name="LoaderSrc"></a> <font size=+1><b><li>Loader Source Code</b></font> <pre> loc code<font color=blue> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UNF SIC/XE LOADER VERSION 1.2 . . . . DEPARTMENT OF COMPUTER AND INFORMATION SCIENCES . . UNIVERSITY OF NORTH FLORIDA . . JACKSONVILLE, FL 32224 . . (904) 620-2985 . . . . FOR USE BY STUDENTS IN COP 3601 . . . . . . . . . . . . . . . . . . . . . . . . . . . .</font> <font color=green>LOADER START 0</font> 0000 B410 <font color=green>CLEAR X</font> 0002 4B202F <font color=green>JSUB GETPAIR</font> 0005 572071 <font color=green>STCH ADDR</font> 0008 4B2029 <font color=green>JSUB GETPAIR</font> <font color=blue>. GET LOAD POINT</font> 000B 57206C <font color=green>STCH ADDR2</font> <font color=blue>. INTO ADDR</font> 000E 4B2023 <font color=green>JSUB GETPAIR</font> 0011 572067 <font color=green>STCH ADDR3</font> 0014 6B2062 <font color=green>LDB ADDR</font> <font color=blue>. MOVE IT TO BASE REG B</font> 0017 4B201A <font color=green>JSUB GETPAIR</font> 001A 57205C <font color=green>STCH ADDR</font> 001D 4B2014 <font color=green>JSUB GETPAIR</font> <font color=blue>. GET START ADDR</font> 0020 572057 <font color=green>STCH ADDR2</font> <font color=blue>. INTO ADDR</font> 0023 4B200E <font color=green>JSUB GETPAIR</font> 0026 572052 <font color=green>STCH ADDR3</font> 0029 4B2008 <font color=green>LOOP JSUB GETPAIR</font> <font color=blue>. GET A BYTE OF SOURCE</font> <font color=green>BASE ADDR</font> 002C 57C000 <font color=green>STCH ADDR,X</font> <font color=blue>. STORE AT B+X WITH 0 DISP</font> <font color=green>NOBASE</font> 002F B810 <font color=green>TIXR X</font> <font color=blue>. (X)=(X)+1</font> 0031 3F2FF5 <font color=green>J LOOP</font><font color=blue> . . SUBROUTINE TO INPUT THE NEXT 2 CHARACTERS (HEX) . CONVERTING TO NUMERIC FORM IN RIGHTMOST BYTE OF A .</font> 0034 172045 <font color=green>GETPAIR STL RTADDR</font> <font color=blue>. SAVE RETURN ADDRESS</font> 0037 4B200E <font color=green>JSUB READ</font> <font color=blue>. GET 1ST HEX DIGIT,</font> 003A A403 <font color=green>SHIFTL A,4</font> <font color=blue>. SHIFT LEFT TO CORRECT</font> 003C 572040 <font color=green>STCH HEX</font> <font color=blue>. POSITION & HOLD IT</font> 003F 4B2006 <font color=green>JSUB READ </font> <font color=blue>. GET 2ND HEX DIGIT,</font> 0042 472038 <font color=green>OR ORADDR</font> <font color=blue>. "OR" IT WITH THE 1ST</font> 0045 3E2034 <font color=green>J @RTADDR</font> <font color=blue>. TO FORM THE FULL BYTE</font><font color=blue> . . SUBROUTINE TO INPUT A CHARACTER (HEX) . AND CONVERT IT TO NUMERIC FORM .</font> 0048 E100F1 <font color=green>READ TD #X'F1'</font> <font color=blue>. TEST DEVICE (DEVF1)</font> 004B 332FFA <font color=green>JEQ READ</font> <font color=blue>. LOOPING UNTIL READY</font> 004E B400 <font color=green>CLEAR A</font> 0050 D900F1 <font color=green>RD #X'F1'</font> <font color=blue>. INPUT CHARACTER TO REG A</font> 0053 290030 <font color=green>COMP #48</font> <font color=blue>. SKIP IF NOT A</font> 0056 3B200F <font color=green>JLT EOFCK</font> <font color=blue>. HEX CHARACTER</font> 0059 1D0030 <font color=green>SUB #48</font> <font color=blue>. CONVERT FROM</font> 005C 29000A <font color=green>COMP #10</font> <font color=blue>. CHARACTER TO</font> 005F 3B2003 <font color=green>JLT GOBACK</font> <font color=blue>. NUMERIC FORM</font> 0062 1D0007 <font color=green>SUB #7</font> 0065 4F0000 <font color=green>GOBACK RSUB</font> 0068 290021 <font color=green>EOFCK COMP #33</font> <font color=blue>. EXIT ON "!" CHARACTER</font> 006B 332006 <font color=green>JEQ EXIT</font> 006E 290004 <font color=green>COMP #4</font> <font color=blue>. EXIT ON EOF</font> 0071 372FD4 <font color=green>JGT READ</font> 0074 B420 <font color=green>EXIT CLEAR L</font> <font color=blue>. SET RETURN TO SYSTEM</font> 0076 3E2000 <font color=green>J @ADDR</font> 0079 FF <font color=green>ADDR RESB 1</font> <font color=blue>. STORAGE 1ST FOR LOAD POINT</font> 007A FF <font color=green>ADDR2 RESB 1</font> <font color=blue>. THEN FOR START ADDRESS</font> 007B FF <font color=green>ADDR3 RESB 1</font> 007C FF <font color=green>RTADDR RESB 1</font> <font color=blue>. STORAGE FOR RSUB RETURN;</font> 007D FF <font color=green>ORADDR RESB 1</font> <font color=blue>. THESE 2 BYTES USED BY</font> 007E FF <font color=green>RESB 1</font> <font color=blue>. "OR"; EFFECT ON BYTE</font> 007F FF <font color=green>HEX RESB 1</font> <font color=blue>. NAMED "HEX" IS ONLY</font> <font color=green>END LOADER</font> <font color=blue>. PART USED</font> </pre> <p>  <a name="LoaderObj"></a> <font size=+1><b><li>Contents of the file "<font color=blue>loader</font>"</b></font> <pre><font color=red> B4104B202F5720714B202957206C4B20235720676B20624B201A57205C4B2014 5720574B200E5720524B200857C000B8103F2FF51720454B200EA4035720404B 20064720383E2034E100F1332FFAB400D900F12900303B200F1D003029000A3B 20031D00074F0000290021332006290004372FD4B4203E2000FFFFFFFFFFFFFF</font> </pre> <p>  <a name="DumpEx"></a> <font size=+1><b><li>Reading a SIC Dump</b></font> <p> <p> A dump instruction such as <pre> <font color=blue>d r,0-1f</font> </pre> <p> causes a dump of the registers and SIC memory including addresses from <font face="Courier" color=blue>0000</font> through <font face="Courier" color=blue>001F</font> with the result: <pre><font color=red> A=FFFFFF X=FFFFFF L=FFFFFF B=FFFFFF S=FFFFFF T=FFFFFF P=000000 CC=LT 0000 B4104B20 2F572071 4B202957 206C4B20 0010 23572067 6B20624B 201A5720 5C4B2014</font> </pre> <p> In this case each of the registers (<font face="Courier" color=blue>A</font>, <font face="Courier" color=blue>X</font>, <font face="Courier" color=blue>L</font>, <font face="Courier" color=blue>B</font>, <font face="Courier" color=blue>S</font>, <font face="Courier" color=blue>T</font>) has value <font face="Courier" color=blue>FFFFFF</font>, the program counter (<font face="Courier" color=blue>P</font>) has the value <font face="Courier" color=blue>000000</font> indicating the instruction at memory location <font face="Courier" color=blue>000000</font> is what will be executed next and the condition code (<font face="Courier" color=blue>CC</font>) is currently set to less than (<font face="Courier" color=blue>LT</font>). <p> <p> Taking the dump instruction from the example of Section 5: <pre> <font color=green><b>d 100-110</b></font> <font face="Times", size=3>[<i>dump of the section of memory holding the loaded code</i>]</font> <font face="Times", size=3>[<i>result boldfaced</i>]</font><font color=red> 0100 01000C19 00070F20 034F0000 <font color=blue><b>000013</b></font>FF 0110 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF</font> </pre> <p> simply count <font face="Courier" color=blue>0</font> through <font face="Courier" color=blue>F</font> in pairs along each row to find a desired location <pre><font color=red> 0100 01000C19 00070F20 034F0000 <font face="Courier" color=blue>000013</font>FF</font><font color=blue> ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ 0 1 2 3 4 5 6 7 8 9 A B C D E F</font> </pre> <p> and add the lead location to find the memory address. In particular, you then find that the underlined part begins at <font face="Courier" color=blue>0100+C = 010C</font>. This is precisely the location of "<font face="Courier" color=blue>SAVA</font>" where the program stored its result. A dump is a good way of verifying correctness of intermediate stages of a program under construction. <p>  <a name="Utilities"></a> <font size=+1><b><li>Additional Support Utilities</b></font> <p> <b>SIC/XE assembler</b> <p> SIC assembler source files can be assembled to the loader format of Section 6 by using the SIC/XE assembler. <p> For source code stored in the file "<font face="Courier" color=blue>sicprog</font>" the usage is <p> <font face="Courier"><font color=blue>     sicasm </font>sicprog</font> <p> The assembler report is then stored in the file "<font face="Courier" color=blue>sicprog.lst</font>" and the object code in the file "<font face="Courier" color=blue>sicprog.obj</font>". Since file names are limited to a maximum of 14 characters, be cautioned that the source file name can be no more than <font color=blue><b>10</b></font> characters (including "<font face="Courier" color=blue>.</font>"). <p> The object program (<font face="Courier" color=blue>sicprog.obj</font>) can be loaded and executed under the SIC simulator by setting file name <font face="Courier" color=blue>DEVF1</font> to the object file name (<font face="Courier" color=blue>sicprog.obj</font>). <p> <b>SIC integer files</b> <p> Since SIC uses 24 bit integers, a utility is available to COP 3601 classes which will generate files organized as 24 bit integers. These files can then be processed by SIC programs directly (note that the loader described in Section 6 has to do its own conversion from a text file format to a binary format; if the object program was stored in a binary rather than a text format, a much faster loader could be devised). <p> The utility is called "<font face="Courier" color=blue>sicdtoh</font>" and is invoked by executing <p> <font face="Courier" color=blue>     sicdtoh</font> <p> The user is prompted for the target file name and interactively enters (in decimal or in hex) the integers to store in the file in 24 bit format. The Unix command "<font face="Courier" color=blue>od</font>" can be used to examine the contents of the file produced by <font face="Courier" color=blue>sicdtoh</font>; for example, <p> <font face="Courier"><font color=blue>     od </font>-x sicint</font> <p> will display the file "<font face="Courier" color=blue>sicint</font>" in hex form. <br>  </td></tr></table> </td></tr></table> </body>