Write a PEP/8 machine language simulator that simulates the PEP/8 computer and instruction set for only the following instructions:

computer science

Description

PEP8 SIMULATOR MIDTERM PROJECT

 

GOAL: Write a PEP/8 machine language simulator that simulates the PEP/8 computer and instruction set for only the following instructions:

 

Instruction Specifier

Instruction

Addressing Modes

Status Bits

0000 0000

Stop execution

NA

 

0001 100r

Bitwise invert r

NA

NZ

0001 110r

Arithmetic shift left r

NA

NZVC

0001 111r

Arithmetic shift right r

NA

NZC

0010 000r

Rotate left r

NA

C

0010 001r

Rotate right r

NA

C

0011 0aaa

Decimal input trap

d

NZV

0011 1aaa

Decimal output trap

d, i

 

0100 1aaa

Character input

d

 

0101 0aaa

Character output

d, i

 

0111 raaa

Add to r

d, i

NZVC

1000 raaa

Subtract from r

d, i

NZVC

1001 raaa

Bitwise AND to r

d, i

NZ

1010 raaa

Bitwise OR to r

d, i

NZ

1100 raaa

Load r from memory

d, i

NZ

1101 raaa

Load byte from memory

d, i

NZ

1110 raaa

Store r to memory

d

 

1111 raaa

Store byte r to memory

d

 

 

 

 

 

 

 

Here are some specifics.

 

  1. Use an array to represent the memory.
  2. Use variables or arrays for the PEP8 registers. I recommend putting it all into a structure. I also recommend using an array of 16 bit values for A, X, PC, SP so that you can use the r bit from the instructions to point directly to A or X. You do NOT have to include the Status bits.
  3. Use unions of structures to break up the registers and instructions into the correct bits (for example, use a structure that can be unioned to break up the 8 bit specifier into the following bit combos (4, 1, 3), (5, 3), (7, 1), (8). This will allow you to instantly extract the instruction, register and addressing modes from each instruction. Also use a union to break up the 16 bit operand into two 8 bit values.
  4. Have the instructions be inputted either through the command line or better yet, through a file, in the following format for each instruction:
    1. 6 Hexadecimal characters per instruction
  5. After each instruction in the program is executed, output the PEP8 machine register values.

 

 

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