AssemblerTwo

Hobbyist assembly language, assembler, and virtual machine

Machine Definition

The virtual machine is a 16-bit byte-addressed processor that has:

• 16-bit Program Counter (64k Address Space)
• Registers: A, B, C, D, E, F, G, H, I, J, K, L, M, N, P, S.
  • A ... N - General purpose registers
  • P - General purpose register with conventions
  • S - Stack Pointer register manipulated by PUSH, POP, CALL, RET & others
  • Each register 16 bits wide 0x0000 ... 0xFFFF
• No hard-wired accumulator; most instructions are target/operand type (ie ADD A,B)

See /Documents/opcodes.txt for the complete instruction listing. Please note that the list of opcodes in still in active design/development and can change without notice. Some opcodes in the list have yet to be implemented in code

Sample Code

; MSG routine to print a null-terminated string, the first address
; of the string is passed as an argument via the P register
MSG: LOAD    P,M   ; Load the word at `P` into `M`
     HI      M,N   ; Put HI byte of `M` into `N`
     REZ     N     ; If `N` equals 0, return (we're done)
     COPY    N,A   ; Copy `N` into `A`
     CALL    PCHAR ; Print the char
     LO      M,N   ; Put LO byte of `M` into `N`
     REZ     N     ; if `N` equals 0, return (we're done)
     COPY    N,A   ; Copy `N` into `A`
     CALL    PCHAR ; Print the char
     ADDI    P,2   ; Increment the pointer
     JUMP    MSG

AssemblerTwo.Cmd

Contains the command line progam for working with the Assembler and the VM.

AssemblerTwo.Cmd.exe -f ./target-file.asm

Will attempt to build target-file.asm and if successful will promt you to either exit the progam or launch into the virtual machine.

• /Sources/ has asm programs that can be assembled and executed.
• Try AssemblerTwo.Cmd.exe -f ./Sources/pangram.asm2.txt!

Alternate modes

• -m build -f ./target-file.asm -o ./out-file.a Will build the target-file.asm assembly and write the assembled binary to out-file.a
• -m run -f ./target-binary.a Will attempt to load target-binary.a as binary and launch the simple virtual machine.
• -m vterm -f ./target-binary.a Will attempt to load target-binary.a as binary and launch the virtual terminal.

vterm (virtual terminal)

It's neat!

F1 - Start/Stop VM execution.

F2 - Single Step & Stop

F3 - 100 Steps & Stop

AssemblerTwo.Lib

Primarily contains the actual Assembler code, as well as misc support code.

This library can stand alone if you want to embed the assembler in another project.

AssemblerTwo.Machine

Contains only the virtual machine and minimal support code.

This library can stand alone if you want to embed the virtual machine in another project.

Misc

• Documents/Misc/npp_asm2.xml Notepad++ User Defined Language file for the asm language.