MARIE Data Path Simulator Help - Version 1.0

Getting Started

The MARIE machine environment animates the data 
path activities that take place within the MARIE
computer. This simulator traces the execution of
an assembled MARIE assembly language program as
data is moved between each of the registers and
main memory. When the value stored in a register
changes, the contents of all registers are 
printed in the trace window.

Running a Program

Before you can run a program in the simulator, 
you must first assemble it using the facilities
of the main MARIE machine simulator, MarieSim. 
Once you have an executable program, load it 
and run it using the buttons in the menu bar 
of the simulator.

To observe the details of the data movement, 
you can slow down the execution speed using the
[Set Speed] menu bar button. We have noticed 
that when the speed is set so that execution is
very slow, the "fetch" process of the fetch-
decode-execute cycle can become boring to watch
over and over.  To relieve this boredom, we 
have provided a [Fast Fetch Mode x] button 
to bypass the delay during the instruction 
fetch process. 

While your program is running, components
that are involved in a data trnsfer operation 
change to a bright color. The control unit
determines when each component will be 
activated. 

As explained in the text, each register has 
an identifying number.  This value determines 
which register will be read from, and which 
will be written to.  The control unit sets 
the binary number of each register on the 
read and write control lines according to 
the needs of the instruction being executed. 
The register numbers (in decimal) are as 
follows:

   IR  = 7  OUT = 6  IN  = 5
   AC  = 4  MBR = 3  PC  = 2
   MAR = 1  Main memory = 0

When you run a program, you will see how 
these binary numbers translate into control
signals on the control lines.

Using the controls on the menu bar, you can 
run or stop execution, step through execution,
and reset the simulator.

When you are finished, you may print the 
contents of the register trace as a record
of the activites that have taken place in 
the data path simulator.

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