Pedagogic Value in Understanding Computer Architecture of Implementing the Marie Computer from Null and Lobur in the

Logic Emulation Software, Multimedia Logic

Timothy Stanley*, Daniel Prigmore*, Scott Mikolyski, George Embrey, Leslie Fife, Don Colton

Brigham Young University – Hawaii* Presenters

Outline

• Background (Assignment Approach)• Choice of Marie by Null and Lobur

– Simulated Computer with Data Path Animator– Assembler and Editor– Used for Computer Organization Classes

• Marie Emulated in Multi-Media Logic– Requires building the data path – Requires designing the control circuitry – Runs programs assembled with Null’s Marie

Assignment Approach

• Ask for a one page design specification• Show an example specification• Work through development to specification• Have weekly status reports• Present designs to Dean, Department

Chairs, and interested students

MARIE* by Null & Lobur

* Machine Architecture that is Really Intuitive and Easy

Binary Hex Instruction Meaning0000 0 J nS X Store the PC at address X and jump to X=10001 1 Load X Load contents of address X into AC.0010 2 Store X Store the contents of AC at address X.0011 3 Add X Add the contents of address X to AC.0100 4 Subt X Subtract the contents of Address X from AC.0101 5 Input Input a value from the keyboard into AC.0110 6 Output Output the value in AC to the display.0111 7 Halt Terminate program.1000 8 Skipcond Skip next instruction on condition.1001 9 J ump X Load the value of X into PC.1010 A Clear Sets AC to zero.1011 B AddI X Add indirect: Go to address X. Use the value at X as

the actual address of the data operand to add to AC.1100 C J umpI X J ump indirect: Go to address X. Use the value at X as

the actual address of the location to jump to

Instruction Number

Marie User Interface

Marie Data Path Simulator

Marie in Multimedia Logic*

• Machine codes from Assembly Listing– Need to separate into higher and lower byte– Copy into separate 8 bit RAM chips in MML

• Full implementation except skip conditional if Acc < 0– Did not know how to test for Acc < 0– Worried about unsigned numbers

* Mulimedia Logic (MML) software by George Mills, available at Softronix.com

Memory Address Register (MAR)

Memory Buffer Register (MBR)

Accumulator and ALU

Input Register

Output Register

Instruction Register (IR)

Memory

Program Counter & Incrementer

Bus

Control Logic & Decoder ROM

Instruction Decoder ROM

Conditional Execution Logic

Input / Output Interface

Results & Conclusions

• Understanding through design & building– Data Paths– Address Bus– Control Logic and Bus– Programming with a limited instruction set– Machine language programming

• A deep appreciation for computers, operating systems and compliers