Ncurses-LC3-Simulator

-- Work in Progress --

An ncurses simulator for the LC-3.

It is able to assemble, and run, programs. Assembly is still a work in progress, but it works for the most part.

Usage:

./build.sh

Then, to assemble your LC-3 file:

$ ./LC3Simulator --assemble file [--assemble-only]

Without --assemble-only the simulator will run right after assembling (assuming there were no errors during assembly).

To run your program in the simulator:

$ ./LC3Simulator --objectfile file

Keymappings

Note: Each key is case sensitve.

The following can also be found in includes/Keyboard.h.

Main Menu

Function	Key
Simulator Mode	s
Memory Mode	m
Log dump	d
File Select	f
Quit	q

Simulator

Function	Key
Start	s
Go back	b
Step next	n
Toggle Pause	p
Restart	R
Continue	c
Reset & Continue	C
Quit	q

Memory

Function	Key
Edit Line	e
Go back	b
Jump to line	j
Toggle Breakpoint	B
Move up one line	UP
Move down one line	DOWN
Quit	q
Set PC to address	S

LC-3 Assembly

Each instruction in the LC-3 is 16 bits long. The bits are split differently depending on what instruction it is, however the upper 4 bits are reserved for the opcode.

There are 8 registers in the LC-3, labeled R0 to R7. R7 is generally used to hold the return address (and is assumed as such for instructions such as RET).

The following are the possible instruction for the LC-3:

• AND
• ADD
• BR
• JMP
• JSR
• JSRR
• LD
• LDI
• LDR
• LEA
• NOT
• RET (This is a shortcut for JMP R7)
• RTI
• ST
• STI
• STR
• TRAP

A TRAP is a special instruction in the LC-3 -- it calls a built-in subroutine for the Operating System running inside the LC-3. A valid TRAP operand is one of the following:

• 0x25 (HALT)
• 0x24 (PUTSP)
• 0x23 (IN)
• 0x22 (PUTS)
• 0x21 (OUT, PUTC)
• 0x20 (GETC)

Some example LC-3 Assembly Files can be found in the Examples directory.