Sim8 Quick Start Guide

This sections gives a brief outline of how to download, install, and run the Sim8 microcomputer simulation. For more detailed information on the use of Sim8, see the documentation index.

Step1: Install Java on your computer

In order to run Sim8 you need to have the Java runtime environment installed on your computer. This guide does not explain how to download and install Java.

Step2: Download the Sim8 software

Get one of these files:

• Sim8.jar
• Sim8-13Feb2002.tar
• Sim8-13Feb2002.zip

Step3: Run the simulator and load a program

• Go into the directory Sim8 was installed in

• Type: java -jar Sim8.jar

  This will bring up the main Sim8 "Console" on your screen. The console contains a display of all the CPU registers, and it has several buttons on it, including buttons that say "Power", "Load", and "Run." Near the top of the console are two menus labeled "Settings" and "Information."

• Press the "Power" button to turn the computer on.

• Go to the "settings" menu and within that to the "memory" submenu. Choose the "Show Window" item. The "Sim8 Memory" window should appear. This window shows all 256 memory locations. The default display is in Hex, but you can change it to Decimal or Binary by doing:
  Settings->Memory->Display in Decimal (for example.)

  Notice that all memory locations start out as zero.

• Press the "Load" button. This will bring up a file chooser dialog. You should see the files in the "Programs" directory. Among these should be a file called "count.ldf" Select this file and load it by pressing the "OK" button. Note that the first several locations of memory have changed to the values of the loaded program.

• View the "count.ldf" file using the editor of your choice. It should look something like this:

  # This program counts from 1 to 10
  !locdec
  !valbin
  #       lda     0
  000:00011100
  001:00000000
  #loop   add     1
  002:00111100
  003:00000001
  #       out
  004:11110001
  #       cmp     10
  005:10101100
  006:00001010
  #       jlt     loop
  007:00001101
  008:00000010
  #       halt
  009:11111111
  

  Some comments about the load file format: First, any lines that start with the "#" character are treated as comments by the loader. The comments in the file above contain "mnemonic" representations of the machine language instructions, i.e. assembly language.

  The lines that have the form "number:number" provide the data which is actually loaded into Sim8 memory. The number before the ":" is the memory location which is to be loaded. The number after the ":" is the value which is to be loaded into that location.

  The line "!locdec" tells the loader that the location field in this load file is specified in decimal. The "!valbin" line indicates that the value field is binary. It's convenient to specify machine language instructions in binary because it makes it easy to encode and decode the various bit fields.

• Now go back to the Menus and do: Settings->Output->Show Window
  This should display the "Output" window.

• Then press the "Run" button. You should see the program count from "01" to "0a" in the output window. The default displays are all in hex. If you would rather see the output in decimal, do:
  Settings->Output->Display in Decimal.

• If you want to re-run the program, you need to press the "Reset" button first, so set the program counter back to zero. Pressing reset clears all the registers. Turning "Power" off and on clears everything including zeroing out any programs loaded into memory.

• If you are having problems, do: Settings->Debug Window->Show Window
  This will bring up a window which displays error messages.